2010 Jeep Grand Cherokee misfire nightmare
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- čas přidán 28. 03. 2024
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We used to see this all the time in the jeep liberty. Customer would start up the car and make it about a 100’ before it would lose power and start misfiring.
What often happens is the O2 sensor doesn’t heat up fast enough on one bank but the computer programming allows closed loop operation as soon as one upstream O2 sensor has activity. The sensor that is slow to warm is often still sitting at a higher voltage so the computer thinks that bank is running rich and pulls all the fuel away causing a lean misfire.
A few minutes later the both O2 sensor are warmed up and the misfire goes away.
After having issues in the past we only replace Chrysler upstream sensors as a pairs and use OEM parts or NTK.
Your sensor was biased low causing a rich condition at times which I haven’t seen.
Sometimes the scan data has two PIDs for the O2 sensor voltage. A 0-1v PID and a true voltage PID which has 2.5v or 3v bias iirc.
Most of these sensor start out at 5v when cold so I graph all 4 sensor on a cold start and see how long it takes for the voltage to drop down and start oscillating. Often times you will see one sensor lag behind the other. Compare both upstream sensor against each other and both down stream sensors against each other. The down stream will normally take longer to warm up than the upstream so don’t compare downstream to upstream.
Sweet issue! Too bad the customer spent all that extra cash on the other unnecessary parts, but it happens. At least now it’s fixed and they will be happy.
THANK YOU FOR YOUR TIME !!!!!!!!!!!!!!!!!!!!!!!!!!
Thank you for watching
Thats exactly what it was. This thing is running like a new car.
Definatly recommend. Will come back with my 07 lassic silverado. Thanks oz I know u were the right man for job.
Thanks for taking the time to share this information!
Great work Mr Oz
You are the best teaching us how tobuse data live on the scanner to find the real issue
Another great diag. Thanks Oz!
Excellent diagnostic! The Open Loop Fault status for bank one, once you got it to come up, was the key to the rest of it. Noice!
Great diag, Thanks for sharing!
OZ, Brother u always rock and thanks for going extra step to show obd2 data and misfire in it that made it clear bank # 1 is the problem well done thanks for sharing. cheeeeeers
Hello everyone
- Closed loops indicates that fuel consumption based on maps that’s commonly use when cold engine and open loop shows that fuel consumption based on airflow sensor, oxygen sensor and other sensors readings , if I wrong plz correct my mistake. high Woltage of first sensor indicate that fuel is lean. reason of lean mixture mainly is high air and low fuel. smoke test may be useful in this case.
- waves of first oxygen sensor must have same altitude otherwise it’s dead or tired out. first oxygen sensor have direct influence on air fuel mixture and sometimes it sends wrong information to computer when heating up that indicates it’s dead cz it may stuck on both high or low voltage, -second oxygen sensor only indicates catalyst converting properties, it has horizontal continuous line on graph, if there is not catalyst then graph of second oxygen sensor replying praph of first sensor. second oxygen sensor doesn’t have any influence to air fuel mixture.
Just had a similar issue on my 07 GC with a 4.7.
Problem was dust accumulation in the connectors going into the pcm.
unplugged everything, blew it out, no issues for last 2 weeks.
Nice job
I try to explain to techs about the back door ways of that side but.,, 😪 also weird cause in those u click on “which cylinder is misfiring” and It usually shows.
DTCs are in a particular order for a reason, i typically focus on the lowest number code when there are numerous DTCs.
Waste spark systems tend to lie about the misfires detected
nice n yeah on the dodges gotta do mode 6
Experience diagnosis master mui bueno men saludes noel
I believe you are correct.
I got my money on o2 sensor 1. Had several similar experience with chevy vans. Just fixed my dads van with same issue. I recommend you replace both bank sensor 1. Hope all is well my bro.👍
Btw G. Someone called me yesterday wanting to get your number. They said they contacted you before
@@OzMechanics yes he was able to contact me. Cool dude. Ill have to the story with you. He is having an issue with an ac that has him very frustrated. Hopefully we'll get it squared away. At least pointed in the right direction. Thanks
Adding fuel? Vacuum leak?
I think you've got it. B1S2 proved it!
When you look at B2S1graph and B2S2 graph, they show what's correct!
NICE DIAG!
I would check the oil see if it high and has gas in it if it does even when you change it the down stream will read rich
Oil would cause both backs to read. Only one read a difference
You know a lean condition makes it run rich if you don’t want to check it then don’t
Fun fuel Trip diagnosis o'z
Obd ii generic mode is always the key,!
Thanks man
I have a 11 jeep CherokeeI done a tune up and Oxygen sensors and the car still miss Firing
Maybe we mechanics should start informing customers car owners about the price hike coming up to repair their cars thanks to the nastf new rule taking effect soon.
For the most part it will only be changing the immobilizer function we use. Every day scan tool function won’t be affected.
@ThePracticalMechanic agree, but fine print says anything oe determines it's security, swapping any electronic part that needs pin codes to program. Bcm/ecm/abs/ebcm, etc. rude awaking coming and cost hikes for any car owners repairs.
Show the fix ? Part 2?
Nothing too special fuel trims showed normal. oxygen sensor was fluctuating from .200 .800 didn’t see no fun in that. Wanted to focus on the diag part
@@OzMechanics 🫤👍🏻
Sensor 2 usually does what sensor 1 does, when they both work....
Are you saying downstream copies upstream ?
No way they copy data 😮 ..if they copy how computer see it and manipulate fuel trims?
Wrong.
Rule of thumb When upstream is lean & Downstream is rich 🤔 its a red 🚩
dead wrong if sensor 2 copy senor 1 that means the catalytic is bad not doing its job simple what goes in goes out.