Thank you for the kind words! We take a lot of pride in the work we produce, we are humbled by your words. Takce Care, Mark Hicks Wells Vehicle Electronics
Just purchased a 1997 k1500 5.7l that is throwing a Fuel Injector code. Will be diagnosing. I suspect this job you've superbly detailed will be coming my way soon. Great job on the vid. I'm a new subscriber as of today. Thank you!
Because of the HC, Co and Co2 readings it appeared to be running rich. We didn't need to check fuel pressure, we just needed to confirm it was not the computer holding the injector open. We confirmed this with the noid light. But you are right another way to check it is by checking for pressure leak down. Great question! Thank you, Mark Hicks Wells Vehicle Electronics
@maycor1076 You are right looking at Lambda would have helped. However like you said not many shops have this equipment, so we decided to stick with mainly the HC and CO readings. Hooking the noid light to the harness took only a few minutes to confirm the PCM was triggering properly. I am pleased you liked the video. We are working on some as we speak I am sure you will also enjoy. Take Care Mark Hicks
You bet it could! Certainly, if the trigger wheel is connected to it. the only way to be certain is to watch the triggers with a labscope. I suggest watching the crank and cam sensor signals at the same time. taking note of any deviation. watching them together will give you a point of reference. You could also use an injector trigger to do it. What kind of vehicle are you talking about? Mark Hicks Wells Vehicle Electronics
I believe you are correct. The voltage needed to bridge an air gap goes up as the gap width increases. Because the wider the air gap the more force is required to ionize the air within the gap. This is a good question.
Ed thank you for the professional comment. If someone wants to do it by the book, they should follow your advise. However, when distributors were adjustable how were they positioned on the engine? Part of the tune up process was to set the timing. Not because the distributor moved, it was because of the extra movement in the timing chain and gear correlation, cam and distributor gear and distributor bushings. Mark Hicks Wells Vehicle Electronics
I have a 97 blazer 4x4 4.3 did a lower intake gasket replacement put every thing back the way i took it apart i market every thing to line it all back up. now i have a misfire on cyl #6 i have spark at the distributor and at the end of the spark plug wire. put new ac delco plugs in and still has a misfire. so im thinking its a fuel problem but i know i had a lil peace of grease/oil chunk wedged on the lip of the intake valve so maybe its not closing all the way and making me lose compression???
Hey its rich so now my blazer runs good what i did was made a tester for the spider injectors an test all 6 of them and come to find out all 6 were clicking so i thought they were good so i pulled out the #6 poppet injector out ( with the upper intake off ) put the fuel lines back on turned the ignition to the on position let the fuel system get some pressure then tested #6 and when it was clicking no fuel came out so i cleaned it and now it sprays fuel put it all back together runs way better
Yes it does. This is called injector pulse width. This is the amount of time an injector is held open allowing fuel to spray. The longer the pulse width the richer the combustion.
The fix was that the injector(s) were leaking. The gaskets needed replacing because of the anti-freeze leak. The first thing to check on your vehicle for poor fuel economy are the O2 sensors. What is the year, make, model of your vehicle? Mark Hicks Wells Vehicle Electronics
An ohmmeter works by send a small aount of current from one lead and calculates the resistance in the circuit by how much of that currents flows through. Sending even a small amount of current through an air bag circuit is not recommended.
It sounds like the injector is stuck open or have a piece of grit holding it open. But there is still a possibility you have a compression problem. I would first put a compression gauge on it and check to see how that cylinder measures to the other two on the same side. Let me know what you find, Mark Hicks Wells Vehicle Electronics
Anti-freeze does flow through the intake to help fuel atomization. On very early vehicles it would also help heat the choke spring. The coolant will be warm, it is on the heated side of the thermostat. Mark
First take a look at the bottom of the sensor. If it has been hitting the crankshaft trigger wheel, there are shims available to move it away slightly. The only way to relearn is with a scan tool, this is the next step. If it can not be relearned, you could have excessive crankshaft run out or a timing chain issue. Please stay in touch to help everyone learn. Mark Hicks Wells Vehicle Electronics
An O2 sensor signal oscillates because as the sensor is reporting a rich signal for example the computer is reacting by leaning the system. Stoichiometric of a 14.7 to 1 ratio is obtained through an average. Mark Mark
@JockyTy An Intake manifold leak is common on your vehicle. Could this cause a P0300? Yes! If you do not have a smoke machine, try spraying carb cleaner around the intake while the engine is idling. If the RPMs change due to the addition of the carb cleaner around the intake it means you have a leak. Good Luck Let me know if you have any further questions. Mark Hicks Wells Vehicle Electronics
1. Install a fuel pressure gauge, and after engine is shut off, is the fuel pressure bleeding down? 2. If pressure is bleeding down, remove the upper intake plenum and check for a leaking fuel pressure regulator. Very common to cause this issue. Please let me know the results of your testing. Mark Hicks Wells Vehicle Electronics
@frank0067 When you new plugs set off this misfire, I am assuming you mean it was OK before the plugs were replaced. In that case my first thought , did you replace the plug again or swap it for another cylinder? Second, was conductive anti-seize compound used? When checking the injector, first check to see if the computer is firing it with a noid light. Another way is to listen to it with a screw driver to your ear. Listen for a clicking sound this would indicate the injector is firing. Mark
Have you checked it for vacuum leaks? If it seems to have started after work was performed, you have to start there and make sure it was done right. A defective fuel pressure regulator on your vehicle is also common to cause this issue. Stay in touch! Mark Hicks Wells Vehicle Electronics
If you have anti-freeze or fuel in the oil and you start the engine it is going travel through the bearing ports ... not a good for furture lubrication. Always drain the oil before you start the engine after any major work. IF you want to then let it warm up and change the oil again it would not be a bad thing. Congrats on tackling a tough job! Please let everyone know how it turns out, Mark Hicks Wells Vehicle Electronics
Good news! As far as the O2s, how is the vehicle overall running, any lack of power, misfire etc. If this seems to be OK front O2s are known to get lazy and don't set a code right away. You might want to check for any pending codes. Changing the front O2s is not a bad dart to throw, if you don't have the equipment to test them. Let me know, Mark Hicks Wells Vehicle Electronics
OK, here is a very skinny explanation of fuel trim. Short term fuel trim (STFT) pretty much follows the O2 signal. When the average of the STFT is 0 the long term fuel trim (LTFT) stays at 0 also. When the STFT averages lets say, +10 the LTFT will start to go negative or take fuel away until the STFT averages near 0 again. 0 is 14.7 to 1. Hope this helps, Mark
In the future we will be producing videos with air/fuel sensor diagnostics. There really is not enough room here to give it the explanation it deserves. Mark
Sorry it took me so long to reply. you said the rear area is really clean. This means that is where the leak is and because the pressure regulator is there it is most likely leaking. Remember, gasoline is a very good detergent. Yes you can pressurize it and see what you get. But i am thinking you found the problem. Let me know Mark Hicks Wells Vehicle Electronics
@66bubbaray Ok if it has spark it means the Crank sensor is working. If you spray carb cleaner of starting fluid into the intake will it start? If it does it means it is lacking fuel. If the fuel pressure is good like you said, the next is to check the quality of the fuel. If that looks good the next is to check the injector circuit. the intake will have to come off to do this. Let me know the results and I will help you from there, Mark Hicks Wells Vehicle Electronics
It is my pleasure to help all i can. Just take a look you will know right away if something is leaking. In fact if you have a good nose you will notice a raw fuel smell before you get the intake off.. Mark Hicks Wells Vehicle Electronics
It is common for a leaking fuel pressure regulator or injector to cause this on your vehicle. Check for about 55-57 PSI fuel pressure at idle. Check for a leaking fuel pressure regulator. Check for washing inside the plenum. You will have to take the intake manifold off. First check for any signs of fuel smell. Check for a leaking fuel injector line. Let me know. The MAF is also common. But you will usually get a code. Mark Hicks Wells Vehicle Electronics
@JockyTy I am sorry I would like to help you but i truly am not a drivetrain expert. If I were to guess i would think it is something in the sync between the front hubs and the transfer case. Mark
There isn't any HC sensors that would last very long constantly subjected to all the elements...that I know of...nice thought though. The challenges of when too much oxygen should be ignored has sparked the creation of the air / fuel ratio sensor. In future videos we will be discussing this topic. Mark
You are right the injector was diagnosed by eliminating everything else. This injector system is not really accessible for accurate diagnostics. Putting the 5 gas probe in the spark plug hole would always show a presence of HC. This would not be a valid test. Mark
@markjhicks yes i did swap the new pulstar with another new pulstar that was working from cylinder #4 and put it into cylinder #1 but still the same thing happened. now this morning i took my van into large outfit ..that mechanic said he put a champion plug in cylinder #1 and everything was great no light no misfire.. so i drove it home..remembering i had a delco plug in cylinder #4 .so i changed it to pulstar, but a misfire came back, not sure which misfire this time.
If you dont have a flex fuel vehicle the computer will compensate for E10 through fuel trim adjustments. On a flex fuel vehicle there is a sensor to tell the computer alcohol content. Go to the Wells website and read the newsletters Volume 11 issues 1 and 2 Present & Future Power trains - are you ready? This is covered in them. Mark
The spec for fuel pressure on your vehicle is 60 - 66 PSI. It bothers me because you are not reaching the value. I still think it is worth your time to remove the top of the intake and inspect the valley for signs of fuel. If the pressure regulator is leaking you will see the area below it all washed clean. Let me know, Mark Hicks Wells Vehicle Electronics
You are right, however with OBDII things have gotten better. Early OBDII systems like this will only allow a limited amount of change, like the 25% percent. On later systems, when the change becomes too great, the system will revert to learned values, preventing for example a catalytic converter failure. Mark
It depends upon the strategy being used by the computer system. On today's vehicles the injector will fire once. On some earlier vehicles that would gang fire the injectors it could fire several times.
Nice video & the states before & after were pretty noticeable... I know this was made years ago; Yet, just caught it for the 1st. time - since I'm been having trouble w/a start-up and seems to be lacking fuel when I step on it (on my Chevy Vortex 5.7L 350cc) ?? Therefore, I was (somewhat) informed that it might be my Spider Injector assy., ?? Thanks again !!
Hey Pietro, the spider injection units are very very common to fail on those trucks. Definitely worth a check. Mike Becker, Senior Technical Instructor
It depends upon how the carbon was formed and the type it is. For example diamonds are one of the best insulators, where graphite also made of carbon, is one of the best conductors.
It sure can, in fact I was just having this discussion with my techs last Friday. Is this when you started experiencing problems? Mark Hicks Wells Vehicle Electronics
Having a similar problem with the truck I'm working on I replaced the coil distributor cap and rotor plugs and wires and I'm still having misfires and cylinders 1 3 and 5 but my fuel trim is at -30 % so it seems to me that the computer is pulling back on fuel is it possible that an injector could be stuck open or injectors stuck open
Thank you for your response, Mike. Yes, it's hard to figure, way down track. But it would seem that you agree that those AFR readings don't look right?
Awesome video! This looks way easier than my former 5.9l intake manifold removal. I definitely will be knocking this out soon, keep up the good videos!
to properly adjust the base timing on this you need to do so with a professional scan tool to reflash your pc with an update which you have to take to your local dealer to do so. by making any other adjustments like loggating the base plate you can cause cross fires and all sorts of stuff
also he said there was ample compression and spark in the wires but the pulstar was wet meaning didn't get ignited ..but we tried 2 new pulstars prior ..only when he put champion in, it did ok.. so when i went home i triggered another misfire by putting back pulstar in #4 cylinder, so i am left thinking that the computer or coil cant handle the capacity of the pulstar plugs ..anyway i went and undid that by putting back the ac delco into #4 .but the misfire light hasn't gone away yet !
@66bubbaray The first thing I would do is check for spark and fuel pressure. When you get these results let me know. You can also call me on our tech line 1-800-558-9770 from 7 am to 7 pm CST. Mark Hicks Wells Vehicle Electronics
i have a 2001 chevy s10 4x4 i had a misfire on it and i replaced all the spark plugs wires disturbitor cap rotary button and ignition coil and it sill have a misfire and the check enine light blinks so i thank it is the Fuel Injectors
each injector should read 11.8 to 13.8 if one is way below that like reading 6.0 it is bad . if one is all over the place an not given a good reading it is ether stuck open or stuck close . this test is to check the resistance in each injector ... now if you have a old spider you can replace the injector . just make sure everything in line up right.
Awesome video. I have had a persistent P300 multiple random misfire code with my 97 Yukon 5.7 liter. SES light on, not blinking. Replaced plugs, wires, cap and rotor several times. Misfire continues. Got really bad on a trip last winter, and SES light flashed on acceleration. Now, also get rear cat efficiency low error code. The misfire seemed to have started about 2 years ago after replacing upper intake manifold gasket. Any recommendations?
i am misfiring on cylinder #1 .. a V6 venture 1998 .. mechanic changed plugs and wire set already, but its still there, this cylinder is behind near firewall hard to reach.. oil looks clean, exhaust too.. new plugs triggered this issue is there an easy way to test this #1 injector in this van without ripping taking apart other things?
Again sorry, I'm having a Randy cylinder misfire. I dont know what else to do or could be causing this. I've replaced the rotor, cap, wires, plugs and injectors. I was told I need a new upper intake gasket. Could that solve my problem? Please help!!
Thanks for the message. I really enjoyed your detailed explanation. I love not just fixing something, but understanding how it fits into the big picture too. I have a downed 96 Chevy Tahoe with a 5.7 liter engine. It's fine until I have to brake. Then it won't see the gears. I have to pull over, restart and it sees the gears again just fine....until I have to brake again. I have been down for over a year now and I was wondering what your recommendations would be. I have 2 lines dropping down out of the brake fluid box, so I can imagine its a brake pressure reset thing, but I'm just guessing. It seems to me there is no signal getting to the computer that I have let off the brake and that I am now excelerating. That's just this 1 gramma's guess. As a diy kinda gal with no tools. I'd like to be able to at least sound intelligent or at least like I've been trying, when my friend comes over to help...Thanks so much.
When you hit the brakes overdrive should release and the transmission should then go into 3rd gear. Have you checked the transmission fluid? Not just for level but also for contamination. Mark Hicks Wells Vehicle Electronics
Blingadera Artisans The only hose I can think of would be to the EVAP system, which has nothing to do with the transmission. Mark Hicks Wells Vehicle Electronics
Hi Mr Mark,I am writing from Tulsa, Oklahoma. Thanks for your reply, I do really appreciate the time you have taken to write to me. I have an Astro van 1995 3.4L Engine that recently broke down on me. I was driving it on the highway and suddenly started to loose power and the engine went dead. I tried to start it again and had no success, the engine wouldn't stay in idle and when I pushed the gas pedal some explosions started to happen and loud noises from the exhaust. Any advice?
It could be an injector sticking. But first give me the year, make model, engine size and what code is being set. I will check it out and give you the most probable causes. Mark Hicks Wells Vehicle Electronics
Mike, very interesting video. Was the rich running condition resolved? Pardon all the questions that follow; I'm having some similar issues and odd readings from fuel trims, so I'm trying to get a handle on what's cause and what's effect... Seems like some contradictory symptoms so I'm puzzled: 1:00 Bank 1 fuel trim is adding 25% more fuel, apparently because something (oxygen sensor?) indicates it is too lean. However, 1:25 the system is running rich overall, leading to poor performance and raw fuel in the exhaust. 1:59 Diagnosis of too much fuel being delivered, either as commanded by the computer or because an injector is sticking open. But shouldn't that result in a rich condition being detected by the oxygen sensor, so that a negative fuel trim would be applied? Is the system erroneously sensing a lean condition and erroneously dumping way too much fuel into bank 1 in an attempt to correct it? Thanks in advance for your thoughts on this.
Hey Nord, this diagnostic and video were done well before I got here. If I understand what was going on correctly, it looks like this thing had bad injectors and bad intake gaskets. A rich and a lean condition. Check out our newer videos, the ones on Fuel trims. I go in depth into the entire system and how it operates. It should help, and you should be able to apply to your problem at hand. Mike Becker, Technical Services Instructor
+Chris Ortega Thanks Chris! We won't be stopping! Our goal is to help make your day better by giving you guys good diagnostics tips and procedures to help you on your way to diagnosing your car. Check back often, we have a new video uploaded every 2 weeks, or better yet you can watch us live the first and third Thursday of every month at noon in your timezone. If you go out to our website www.wellsve.com/wells_tech.html you can click the link and subscribe. We will then send you an email every time we have a new class coming up. Mike Becker, Technical Services Instructor
This comment would be years late - Just saw the vid - Another good show. Just wondered about the 6th reading (AFR) on the 5 gas analyser. The "Before" reading was a touch lean of stoic? Then went leaner after the fix? Is the AFR readout accurate? Or is there some fuel trim going on?
Hey Leslie, wish I could say. This car was worked on years ago, well before I was here. Hard to know exactly what was going on with this thing :( Mike Becker, Senior Technical Instructor
@markjhicks Thank you so much, ive been having non stop problems with my blazer and just want it to run strong again. ill try the carb cleaner later today.
you only had to remove the entire intake because you had that anti freeze leak? correct? i just have bad spider injector unit... misfires,lacks power,runs horrible.. runs very rich.i did everything else..tune up..fuel filter timing chain etc...
ok far as the distributor goes gm designed it to be a non adjustable setup. if you are out of time and its showing up odds are your engine has a lot of miles on it like 120,000 or so. in this case your timing chain has probably stretched and has some free slap in it. motor all data usually recommends replacement of most timing chains and belts around 60,000. your distributor is directly gear drivin by the cam which is directly driven by the crank via your timing chain so dont short cut replaceit
I put new spider injectors in my 97 Chevy Silverado. It has a new fuel pump,spark plugs, wires and it still stalls. Only can start it with starting fluid, then I let it sit to heat the engine up. I got to put it in drive and give it gas and it stalls. Got any ideas?
@markjhicks thank you ill try the carb cleaner later today. The only other problem im having is this look up the video "CHEVY BLAZER LS 4X4 WHEEL NOISE 50-70 MPH" ????? i cant figure out what is causing this. if i put it in 4 hi it goes away please let me know what you think
Hyufor locking bc the fuel presser realtor is leaking fuel in the rear two cycle plus the injector is spaying fuel as well so it makes sense as what he is saying and thurts
Thank you for the kind words! We take a lot of pride in the work we produce, we are humbled by your words.
Takce Care,
Mark Hicks
Wells Vehicle Electronics
Just purchased a 1997 k1500 5.7l that is throwing a Fuel Injector code. Will be diagnosing. I suspect this job you've superbly detailed will be coming my way soon. Great job on the vid. I'm a new subscriber as of today. Thank you!
Any voltage spike in the system could set the air bags off. Disconnecting the battery cuts the odds of this occurrence,
Because of the HC, Co and Co2 readings it appeared to be running rich. We didn't need to check fuel pressure, we just needed to confirm it was not the computer holding the injector open. We confirmed this with the noid light. But you are right another way to check it is by checking for pressure leak down. Great question! Thank you,
Mark Hicks
Wells Vehicle Electronics
Thank you for the kind words, they mean a lot to us!
Mark Hicks
Wells Vehicle Electronics
@maycor1076 You are right looking at Lambda would have helped. However like you said not many shops have this equipment, so we decided to stick with mainly the HC and CO readings. Hooking the noid light to the harness took only a few minutes to confirm the PCM was triggering properly. I am pleased you liked the video. We are working on some as we speak I am sure you will also enjoy.
Take Care
Mark Hicks
Thank you for the kind words. they mean a lot to us!
Mark Hicks
Wells Vehicle Electronics
You bet it could! Certainly, if the trigger wheel is connected to it. the only way to be certain is to watch the triggers with a labscope. I suggest watching the crank and cam sensor signals at the same time. taking note of any deviation. watching them together will give you a point of reference. You could also use an injector trigger to do it. What kind of vehicle are you talking about?
Mark Hicks
Wells Vehicle Electronics
I believe you are correct. The voltage needed to bridge an air gap goes up as the gap width increases. Because the wider the air gap the more force is required to ionize the air within the gap. This is a good question.
Ed thank you for the professional comment. If someone wants to do it by the book, they should follow your advise. However, when distributors were adjustable how were they positioned on the engine? Part of the tune up process was to set the timing. Not because the distributor moved, it was because of the extra movement in the timing chain and gear correlation, cam and distributor gear and distributor bushings.
Mark Hicks
Wells Vehicle Electronics
I have a 97 blazer 4x4 4.3 did a lower intake gasket replacement put every thing back the way i took it apart i market every thing to line it all back up. now i have a misfire on cyl #6 i have spark at the distributor and at the end of the spark plug wire. put new ac delco plugs in and still has a misfire. so im thinking its a fuel problem but i know i had a lil peace of grease/oil chunk wedged on the lip of the intake valve so maybe its not closing all the way and making me lose compression???
Hey its rich so now my blazer runs good what i did was made a tester for the spider injectors an test all 6 of them and come to find out all 6 were clicking so i thought they were good so i pulled out the #6 poppet injector out ( with the upper intake off ) put the fuel lines back on turned the ignition to the on position let the fuel system get some pressure then tested #6 and when it was clicking no fuel came out so i cleaned it and now it sprays fuel put it all back together runs way better
Yes, we did. Thanks for mentioning it. It is very important to note, I missed it in the production.
Mark Hicks
Wells Vehicle Electronics
Yes it does. This is called injector pulse width. This is the amount of time an injector is held open allowing fuel to spray. The longer the pulse width the richer the combustion.
The fix was that the injector(s) were leaking. The gaskets needed replacing because of the anti-freeze leak. The first thing to check on your vehicle for poor fuel economy are the O2 sensors. What is the year, make, model of your vehicle?
Mark Hicks
Wells Vehicle Electronics
Thank you! Your comment means a lot to us!
Mark Hicks
Wells Vehicle Electronics
An ohmmeter works by send a small aount of current from one lead and calculates the resistance in the circuit by how much of that currents flows through. Sending even a small amount of current through an air bag circuit is not recommended.
It sounds like the injector is stuck open or have a piece of grit holding it open. But there is still a possibility you have a compression problem. I would first put a compression gauge on it and check to see how that cylinder measures to the other two on the same side.
Let me know what you find,
Mark Hicks
Wells Vehicle Electronics
Anti-freeze does flow through the intake to help fuel atomization. On very early vehicles it would also help heat the choke spring. The coolant will be warm, it is on the heated side of the thermostat.
Mark
First take a look at the bottom of the sensor. If it has been hitting the crankshaft trigger wheel, there are shims available to move it away slightly. The only way to relearn is with a scan tool, this is the next step. If it can not be relearned, you could have excessive crankshaft run out or a timing chain issue. Please stay in touch to help everyone learn.
Mark Hicks
Wells Vehicle Electronics
I am not sure where you are going with this...but yea I have a table saw, planner and joiner that do.
A is the correct answer
B would show leakage
C would also show leakage
D would not cause low compression
I have a 1999 Chevy Suburban 454 7.4L Vortec. This video was extremely helpful, thank you!
An O2 sensor signal oscillates because as the sensor is reporting a rich signal for example the computer is reacting by leaning the system. Stoichiometric of a 14.7 to 1 ratio is obtained through an average.
Mark
Mark
@JockyTy An Intake manifold leak is common on your vehicle. Could this cause a P0300? Yes! If you do not have a smoke machine, try spraying carb cleaner around the intake while the engine is idling. If the RPMs change due to the addition of the carb cleaner around the intake it means you have a leak.
Good Luck
Let me know if you have any further questions.
Mark Hicks
Wells Vehicle Electronics
1. Install a fuel pressure gauge, and after engine is shut off, is the fuel pressure bleeding down?
2. If pressure is bleeding down, remove the upper intake plenum and check for a leaking fuel pressure regulator.
Very common to cause this issue. Please let me know the results of your testing.
Mark Hicks
Wells Vehicle Electronics
@frank0067 When you new plugs set off this misfire, I am assuming you mean it was OK before the plugs were replaced. In that case my first thought , did you replace the plug again or swap it for another cylinder? Second, was conductive anti-seize compound used? When checking the injector, first check to see if the computer is firing it with a noid light. Another way is to listen to it with a screw driver to your ear. Listen for a clicking sound this would indicate the injector is firing.
Mark
@DFergyferg Thank you for the feedback, it really does mean a lot to us!
Take Care,
Mark Hicks
Wells Vehicle Electronics
Have you checked it for vacuum leaks? If it seems to have started after work was performed, you have to start there and make sure it was done right. A defective fuel pressure regulator on your vehicle is also common to cause this issue. Stay in touch!
Mark Hicks
Wells Vehicle Electronics
If you have anti-freeze or fuel in the oil and you start the engine it is going travel through the bearing ports ... not a good for furture lubrication. Always drain the oil before you start the engine after any major work. IF you want to then let it warm up and change the oil again it would not be a bad thing.
Congrats on tackling a tough job!
Please let everyone know how it turns out,
Mark Hicks
Wells Vehicle Electronics
Good news! As far as the O2s, how is the vehicle overall running, any lack of power, misfire etc. If this seems to be OK front O2s are known to get lazy and don't set a code right away. You might want to check for any pending codes. Changing the front O2s is not a bad dart to throw, if you don't have the equipment to test them.
Let me know,
Mark Hicks
Wells Vehicle Electronics
OK, here is a very skinny explanation of fuel trim. Short term fuel trim (STFT) pretty much follows the O2 signal. When the average of the STFT is 0 the long term fuel trim (LTFT) stays at 0 also. When the STFT averages lets say, +10 the LTFT will start to go negative or take fuel away until the STFT averages near 0 again. 0 is 14.7 to 1.
Hope this helps,
Mark
@frank0067 Either the plug is not firing or the cylinder is being flooded ... possible injector problem. Let me know what happens.
Mark
In the future we will be producing videos with air/fuel sensor diagnostics. There really is not enough room here to give it the explanation it deserves.
Mark
@dtrspre No sorry this is the only injector video we have so far.
Mark Hicks
Wells Vehicle Electronics
They may have been using the injector as a trigger point to keep it steady. Were they looking at voltage or amperage draw?
Mark
Sorry it took me so long to reply. you said the rear area is really clean. This means that is where the leak is and because the pressure regulator is there it is most likely leaking. Remember, gasoline is a very good detergent. Yes you can pressurize it and see what you get.
But i am thinking you found the problem. Let me know
Mark Hicks
Wells Vehicle Electronics
@66bubbaray Ok if it has spark it means the Crank sensor is working. If you spray carb cleaner of starting fluid into the intake will it start? If it does it means it is lacking fuel. If the fuel pressure is good like you said, the next is to check the quality of the fuel. If that looks good the next is to check the injector circuit. the intake will have to come off to do this. Let me know the results and I will help you from there,
Mark Hicks
Wells Vehicle Electronics
Hello,
Check the distributor cap first, then the fuel pressure.
Keep in touch, sorry for the slow reply,
Mark Hicks
Wells Vehicle Electronics
It is my pleasure to help all i can. Just take a look you will know right away if something is leaking. In fact if you have a good nose you will notice a raw fuel smell before you get the intake off..
Mark Hicks
Wells Vehicle Electronics
It is common for a leaking fuel pressure regulator or injector to cause this on your vehicle. Check for about 55-57 PSI fuel pressure at idle.
Check for a leaking fuel pressure regulator. Check for washing inside the plenum. You will have to take the intake manifold off. First check for any signs of fuel smell.
Check for a leaking fuel injector line. Let me know.
The MAF is also common. But you will usually get a code.
Mark Hicks
Wells Vehicle Electronics
If the ports and EGR are open the engine will not idle. The EGR momentarily opens upon acceleration.
@JockyTy I am sorry I would like to help you but i truly am not a drivetrain expert. If I were to guess i would think it is something in the sync between the front hubs and the transfer case.
Mark
Very good Rich! Job well Done! Thanks for the update.
Take Care my friend!
Mark Hicks
Wells Vehicle Electronics
There isn't any HC sensors that would last very long constantly subjected to all the elements...that I know of...nice thought though. The challenges of when too much oxygen should be ignored has sparked the creation of the air / fuel ratio sensor. In future videos we will be discussing this topic.
Mark
You will need to connect through the line. Usually this is done at the throttle body.
You are right the injector was diagnosed by eliminating everything else. This injector system is not really accessible for accurate diagnostics. Putting the 5 gas probe in the spark plug hole would always show a presence of HC. This would not be a valid test.
Mark
by far, the most helpful video for me. thanks for posting, markjhicks
Thank you it means a lot to us!
Mark Hicks
Wells Vehicle Electronics
If it is cracked and shorting to the engine block the secondary resistance will decrease.
@markjhicks
yes i did swap the new pulstar with another new pulstar that was working from cylinder #4 and put it into cylinder #1 but still the same thing happened.
now this morning i took my van into large outfit ..that mechanic said he put a champion plug in cylinder #1
and everything was great no light no misfire.. so i drove it home..remembering i had a delco plug in cylinder #4 .so i changed it to pulstar, but a misfire came back, not sure which misfire this time.
If you dont have a flex fuel vehicle the computer will compensate for E10 through fuel trim adjustments. On a flex fuel vehicle there is a sensor to tell the computer alcohol content. Go to the Wells website and read the newsletters Volume 11 issues 1 and 2 Present & Future Power trains - are you ready? This is covered in them.
Mark
The spec for fuel pressure on your vehicle is 60 - 66 PSI. It bothers me because you are not reaching the value. I still think it is worth your time to remove the top of the intake and inspect the valley for signs of fuel. If the pressure regulator is leaking you will see the area below it all washed clean.
Let me know,
Mark Hicks
Wells Vehicle Electronics
You are right, however with OBDII things have gotten better. Early OBDII systems like this will only allow a limited amount of change, like the 25% percent. On later systems, when the change becomes too great, the system will revert to learned values, preventing for example a catalytic converter failure.
Mark
Great video bro,What scanner are you using to set the distributor to zero? Thanks!!!
It depends upon the strategy being used by the computer system. On today's vehicles the injector will fire once. On some earlier vehicles that would gang fire the injectors it could fire several times.
Slotting the distributor mount is a getho way to avoid the worn out timing chain and gears.
Alright, good to know.
Mike Becker, Senior Technical Instructor
Sounds good ... it is my pleasure!
Mark Hicks
Wells Vehicle Electronics
Running rich and pressure would go up if the return line is restricted.
Low compression will decrease secondary resistance.
Nice video & the states before & after were pretty noticeable... I know this was made years ago; Yet, just caught it for the 1st. time - since I'm been having trouble w/a start-up and seems to be lacking fuel when I step on it (on my Chevy Vortex 5.7L 350cc) ?? Therefore, I was (somewhat) informed that it might be my Spider Injector assy., ?? Thanks again !!
Hey Pietro, the spider injection units are very very common to fail on those trucks. Definitely worth a check.
Mike Becker, Senior Technical Instructor
It depends upon how the carbon was formed and the type it is. For example diamonds are one of the best insulators, where graphite also made of carbon, is one of the best conductors.
It sure can, in fact I was just having this discussion with my techs last Friday. Is this when you started experiencing problems?
Mark Hicks
Wells Vehicle Electronics
Having a similar problem with the truck I'm working on I replaced the coil distributor cap and rotor plugs and wires and I'm still having misfires and cylinders 1 3 and 5 but my fuel trim is at -30 % so it seems to me that the computer is pulling back on fuel is it possible that an injector could be stuck open or injectors stuck open
Hey Tim, the -30 is a pretty good giveaway for these. I bet you have at least one stuck.
Mike Becker, Senior Instructor
Thank you for your response, Mike. Yes, it's hard to figure, way down track. But it would seem that you agree that those AFR readings don't look right?
Yeh, i'd agree. It does look lean. 18+ afr seems high at idle. Not sure why, or what was done.
Mike Becker, Senior Technical Instructor
Awesome video! This looks way easier than my former 5.9l intake manifold removal. I definitely will be knocking this out soon, keep up the good videos!
Hey J Sean Hooper, thanks for watching!
Mike Becker, Senior Technical Services Instructor
to properly adjust the base timing on this you need to do so with a professional scan tool to reflash your pc with an update which you have to take to your local dealer to do so. by making any other adjustments like loggating the base plate you can cause cross fires and all sorts of stuff
Yes, if the noid light would stay on we would know the PCM was holding the injector open.
Mark
also he said there was ample compression and spark in the wires but the pulstar was wet meaning didn't get ignited ..but we tried 2 new pulstars prior ..only when he put champion in, it did ok.. so when i went home i triggered another misfire by putting back pulstar in #4 cylinder, so i am left thinking that the computer or coil cant handle the capacity of the pulstar plugs ..anyway i went and undid that by putting back the ac delco into #4 .but the misfire light hasn't gone away yet !
Sounds good let me know what happens.
Mark Hicks
Wells Vehicle Electronics
Great video, super informative!
+mikemica711 Thanks, glad you liked it!
Mike Becker, Technical Services Instructor
@66bubbaray The first thing I would do is check for spark and fuel pressure. When you get these results let me know. You can also call me on our tech line 1-800-558-9770 from 7 am to 7 pm CST.
Mark Hicks
Wells Vehicle Electronics
i have a 2001 chevy s10 4x4 i had a misfire on it and i replaced all the spark plugs wires disturbitor cap rotary button and ignition coil and it sill have a misfire and the check enine light blinks so i thank it is the Fuel Injectors
each injector should read 11.8 to 13.8 if one is way below that like reading 6.0 it is bad . if one is all over the place an not given a good reading it is ether stuck open or stuck close . this test is to check the resistance in each injector ... now if you have a old spider you can replace the injector . just make sure everything in line up right.
This is an excellent video. Good work.
That will increase secondary resistance, because it will take more current to bridge the plug gap.
Awesome video. I have had a persistent P300 multiple random misfire code with my 97 Yukon 5.7 liter. SES light on, not blinking. Replaced plugs, wires, cap and rotor several times. Misfire continues. Got really bad on a trip last winter, and SES light flashed on acceleration. Now, also get rear cat efficiency low error code. The misfire seemed to have started about 2 years ago after replacing upper intake manifold gasket. Any recommendations?
From what you said it appears to be B.
Best video ever, bless you sir
mike richardson Thank you Mike, your kind words mean a lot to us!
Mark Hicks
Wells Vehicle Electronics
i am misfiring on cylinder #1 .. a V6 venture 1998 .. mechanic changed plugs and wire set already, but its still there, this cylinder is behind near firewall hard to reach..
oil looks clean, exhaust too.. new plugs triggered this issue
is there an easy way to test this #1 injector in this van without ripping taking apart other things?
Again sorry, I'm having a Randy cylinder misfire. I dont know what else to do or could be causing this. I've replaced the rotor, cap, wires, plugs and injectors. I was told I need a new upper intake gasket. Could that solve my problem? Please help!!
Yes it could be.
Thanks for the message. I really enjoyed your detailed explanation. I love not just fixing something, but understanding how it fits into the big picture too. I have a downed 96 Chevy Tahoe with a 5.7 liter engine. It's fine until I have to brake. Then it won't see the gears. I have to pull over, restart and it sees the gears again just fine....until I have to brake again. I have been down for over a year now and I was wondering what your recommendations would be. I have 2 lines dropping down out of the brake fluid box, so I can imagine its a brake pressure reset thing, but I'm just guessing. It seems to me there is no signal getting to the computer that I have let off the brake and that I am now excelerating. That's just this 1 gramma's guess. As a diy kinda gal with no tools. I'd like to be able to at least sound intelligent or at least like I've been trying, when my friend comes over to help...Thanks so much.
When you hit the brakes overdrive should release and the transmission should then go into 3rd gear. Have you checked the transmission fluid? Not just for level but also for contamination.
Mark Hicks
Wells Vehicle Electronics
Blingadera Artisans
The only hose I can think of would be to the EVAP system, which has nothing to do with the transmission.
Mark Hicks
Wells Vehicle Electronics
Hi Mr Mark,I am writing from Tulsa, Oklahoma. Thanks for your reply, I do really appreciate the time you have taken to write to me. I have an Astro van 1995 3.4L Engine that recently broke down on me. I was driving it on the highway and suddenly started to loose power and the engine went dead. I tried to start it again and had no success, the engine wouldn't stay in idle and when I pushed the gas pedal some explosions started to happen and loud noises from the exhaust. Any advice?
It could be an injector sticking. But first give me the year, make model, engine size and what code is being set. I will check it out and give you the most probable causes.
Mark Hicks
Wells Vehicle Electronics
Mike, very interesting video. Was the rich running condition resolved? Pardon all the questions that follow; I'm having some similar issues and odd readings from fuel trims, so I'm trying to get a handle on what's cause and what's effect... Seems like some contradictory symptoms so I'm puzzled: 1:00 Bank 1 fuel trim is adding 25% more fuel, apparently because something (oxygen sensor?) indicates it is too lean. However, 1:25 the system is running rich overall, leading to poor performance and raw fuel in the exhaust. 1:59 Diagnosis of too much fuel being delivered, either as commanded by the computer or because an injector is sticking open. But shouldn't that result in a rich condition being detected by the oxygen sensor, so that a negative fuel trim would be applied? Is the system erroneously sensing a lean condition and erroneously dumping way too much fuel into bank 1 in an attempt to correct it? Thanks in advance for your thoughts on this.
Hey Nord, this diagnostic and video were done well before I got here. If I understand what was going on correctly, it looks like this thing had bad injectors and bad intake gaskets. A rich and a lean condition. Check out our newer videos, the ones on Fuel trims. I go in depth into the entire system and how it operates. It should help, and you should be able to apply to your problem at hand.
Mike Becker, Technical Services Instructor
So where is this shop located. My teucks acting up and i aint trying to mess anything up. Pretty sure its the same issue as shown here
Hey Edwin, thanks for watching! We are located in Fond Du Lac, WI.
Mike Becker, Senior Instructor
great video well detailed and informative, keep making videos like this please
+Chris Ortega Thanks Chris! We won't be stopping! Our goal is to help make your day better by giving you guys good diagnostics tips and procedures to help you on your way to diagnosing your car. Check back often, we have a new video uploaded every 2 weeks, or better yet you can watch us live the first and third Thursday of every month at noon in your timezone. If you go out to our website www.wellsve.com/wells_tech.html you can click the link and subscribe. We will then send you an email every time we have a new class coming up.
Mike Becker, Technical Services Instructor
Excellent news! Happy endings are always a good thing. Ring me anytime, Take care my friend,
Mark Hicks
Wells Vehicle Electronics
how did you guys know the injectors were leaking other than high HC and CO readings? was it also not holding pressure when the car was off?
This comment would be years late - Just saw the vid - Another good show. Just wondered about the 6th reading (AFR) on the 5 gas analyser. The "Before" reading was a touch lean of stoic? Then went leaner after the fix? Is the AFR readout accurate? Or is there some fuel trim going on?
Hey Leslie, wish I could say. This car was worked on years ago, well before I was here. Hard to know exactly what was going on with this thing :(
Mike Becker, Senior Technical Instructor
Ventilation problems.
@markjhicks Thank you so much, ive been having non stop problems with my blazer and just want it to run strong again. ill try the carb cleaner later today.
you only had to remove the entire intake because you had that anti freeze leak? correct? i just have bad spider injector unit... misfires,lacks power,runs horrible.. runs very rich.i did everything else..tune up..fuel filter timing chain etc...
Hey Roadstar499, right. You only have to remove the upper to get to the spider injection unit.
Mike Becker, Senior Technical Instructor
ok far as the distributor goes gm designed it to be a non adjustable setup. if you are out of time and its showing up odds are your engine has a lot of miles on it like 120,000 or so. in this case your timing chain has probably stretched and has some free slap in it. motor all data usually recommends replacement of most timing chains and belts around 60,000. your distributor is directly gear drivin by the cam which is directly driven by the crank via your timing chain so dont short cut replaceit
Will the bad spider injection cause it to smoke from exhaust?
Hey Myron, depends on the failure. If it were stuck open forcing it rich, then sure.
Yea that sounds reasonable.
I put new spider injectors in my 97 Chevy Silverado. It has a new fuel pump,spark plugs, wires and it still stalls. Only can start it with starting fluid, then I let it sit to heat the engine up. I got to put it in drive and give it gas and it stalls. Got any ideas?
@markjhicks thank you ill try the carb cleaner later today. The only other problem im having is this look up the video "CHEVY BLAZER LS 4X4 WHEEL NOISE 50-70 MPH" ????? i cant figure out what is causing this. if i put it in 4 hi it goes away please let me know what you think
Hyufor locking bc the fuel presser realtor is leaking fuel in the rear two cycle plus the injector is spaying fuel as well so it makes sense as what he is saying and thurts
I dont think it does.