Man, I'm surprised not very many people are giving you great Kudos for this great find here. Rename the title Chevy 4.3L Check engine light, low power, I bet that would change. You did an outstanding job finding this very very sneaky problem. The trouble code saying it's lean fuel but really rich fuel! For months I have had problems with low power going up hills and the check engine light would come on and felt, even though I've been told my 1994 C1500, 4.3l V6 does not have a limp mode, it sure DOES feel like it, going up hill, with the pedal smash down, it would down shift ok, but still had a bogging down feeling on the engine and the speed would go down to a dangerous speed of like 45 MPH and cars zooming up on my back bumper, them not realizing how slow I was forced to go down to, because of the wrong fuel mixture signals to the ECM. I have change alot of stuff trying to find this culprit, like a new EGR valve on the engine and recently a big job installing new exhaust manifold pipes to the Catalytic converter where the new O2 sensor was also installed, that was a major pain to do. But don't have any leaks and now the 94 Chevy 4.3L engine has new manifold exhaust pipes, 02 sensor and CAT. Had to cut off the muffler pipe going to the Cat exhaust side and add a 12" flange pipe to match the Cat exhaust flange to bolt together and then a clamp on the end of the flange pipe that just fit over the muffler pipe. Sorry about long winded story. Before reading your find here I was about to check my fuel pump pressure, like on your list, tomorrow, to see if it's low fuel pressure and possible a bad fuel pump, causing this symptom and still will, because I already prepared for. BUT NOW , because of your sherlock holmes find, I'm definitely going to check the possibility of this faulty signal 02 sensor wiring situation. It's funny I just took out the shallow glove box to get access to install a new door jam cabin light switch and never knew that the wiring junction is in there and now know where the signal wiring for this 02 sensor is located! I'll let you know what happens on this attempted fix.
Thanks! (Bear in mind with my input I just do this as a hobby and don't know much) In my case, I never noticed a difference in power. I only knew something was wrong because I check the mileage each fill up and it kept getting worse until I had a check-engine light. See what codes you have and that will give some clues. Then you can leave the jumper in while driving like I did and see what the computer is seeing from the o2. If the light flashes pretty even while in closed loop but still no power, maybe the base timing is off or TPS is bad? I have a video on how I checked the TPS. Might also start with the easy things to check. Is full throttle actually full throttle? If the light indicates lean, and if you don't know when the fuel filter was last done, could throw in a new one and see how it does. I'll put up a video on how I checked fuel pressure on mine since TBI doesn't have a test port. If the pressure was low, my plan was to slowly pinch down on the downstream rubber test line I added to check pressure and see if the pump could increase pressure. I think that would help determine if the low pressure was the pump or pressure regulator. You can pull the plugs and maybe get an indication if it's running really rich or lean and compare that to the light flashes and codes. If you are checking sensor voltages MAKE SURE your meter does NOT have the test lead in the CURRENT (amp) port. The current port will short the computer. Checking sensor voltages is inherently risky so you have to be careful and not short the circuit. czcams.com/video/-4oCAelzrWM/video.html TLDR: Thanks for your kind words. There are several things that could be happening and there is no guide that is going to direct you to the issue. You will have to understand the components and how they interact and figure out what issue or combination of issues could be causing the problem. Then prove that the suspect parts are the problem and fix them. This guy has this playlist showing a lot of info on car sensors and I found them helpful. czcams.com/video/XQYDwIWS6Ho/video.html A good manual, ideally a factory service manual, will have a lot of good info specific to your truck. Sorry for the long reply, Best of Luck!
@@PracticallyStock Really appreciate all this additional information. Bottom line like you said the more you understand where the components are and how they work the quicker the solutions. Update on my fuel pump. For this 1994 Chevy C1500 4.3L, had to put a special T strator adapter to hook up fuel pressure gage. (placed in between the fuel pump line going into the fuel filter) to read the check the fuel pump pressure. That year and model they did not put a strator valve by the engine or the fuel filter underneath the truck on drivers side It's suppose to read 9-12 PSI by the book. It read 1 psi just off the peg. I couldn't believe my eyes so I rented O'Reilly's fuel guage and it read the same of it, 1 PSI. The guy at O'reilly said the can still run on 1-2 psi around town but as you get on the road and try to pass or go up a hill it will lose power, it can't keep up with the demand. So for now I'm going to run the truck to get the tank almost out of fuel and do the dreaded drop the tank and install new pump. I hope that fixes it. But I always have your find to check if the new fuel pump install doesn't get the fuel pressure power back to the engine. What is interesting this Code 44 only says O2 fuel lean, but obviously doesn't mean it's just the O2 Sensor that might be bad, the O2 is just saying you got some kind of Fuel problem. How many different fuel problems can Code 44, 02 sensor Lean, lead to?
1 psi lol. I bet the pump and/or pressure regulator fixes that and the problem goes away. Might replace the filter as well if it seems suspect. I'd check pressure after the repair incase the new pump or regulator is defective. Hard to say how many things can cause a lean code. To my knowledge anything that actually causes a lean condition (dead cylinder, lack of fuel, bad sensor readings, ect) or gives a false lean reading (bad wirings, bad computer, exhaust leaks, wrong sensor, ect) can cause a lean code. From what I read, you have the textbook example of a lean code where there is actually a lean condition because the fuel system can't get enough fuel to the engine. Good find!
I don't remember the plug type but it was the plug on the car's harness that was not making a good connection. I bypassed the signal wire around the car's plug and that fixed the signal issue
Man, I'm surprised not very many people are giving you great Kudos for this great find here. Rename the title Chevy 4.3L Check engine light, low power, I bet that would change. You did an outstanding job finding this very very sneaky problem. The trouble code saying it's lean fuel but really rich fuel! For months I have had problems with low power going up hills and the check engine light would come on and felt, even though I've been told my 1994 C1500, 4.3l V6 does not have a limp mode, it sure DOES feel like it, going up hill, with the pedal smash down, it would down shift ok, but still had a bogging down feeling on the engine and the speed would go down to a dangerous speed of like 45 MPH and cars zooming up on my back bumper, them not realizing how slow I was forced to go down to, because of the wrong fuel mixture signals to the ECM. I have change alot of stuff trying to find this culprit, like a new EGR valve on the engine and recently a big job installing new exhaust manifold pipes to the Catalytic converter where the new O2 sensor was also installed, that was a major pain to do. But don't have any leaks and now the 94 Chevy 4.3L engine has new manifold exhaust pipes, 02 sensor and CAT. Had to cut off the muffler pipe going to the Cat exhaust side and add a 12" flange pipe to match the Cat exhaust flange to bolt together and then a clamp on the end of the flange pipe that just fit over the muffler pipe. Sorry about long winded story. Before reading your find here I was about to check my fuel pump pressure, like on your list, tomorrow, to see if it's low fuel pressure and possible a bad fuel pump, causing this symptom and still will, because I already prepared for. BUT NOW , because of your sherlock holmes find, I'm definitely going to check the possibility of this faulty signal 02 sensor wiring situation. It's funny I just took out the shallow glove box to get access to install a new door jam cabin light switch and never knew that the wiring junction is in there and now know where the signal wiring for this 02 sensor is located! I'll let you know what happens on this attempted fix.
Thanks! (Bear in mind with my input I just do this as a hobby and don't know much) In my case, I never noticed a difference in power. I only knew something was wrong because I check the mileage each fill up and it kept getting worse until I had a check-engine light. See what codes you have and that will give some clues. Then you can leave the jumper in while driving like I did and see what the computer is seeing from the o2. If the light flashes pretty even while in closed loop but still no power, maybe the base timing is off or TPS is bad? I have a video on how I checked the TPS. Might also start with the easy things to check. Is full throttle actually full throttle? If the light indicates lean, and if you don't know when the fuel filter was last done, could throw in a new one and see how it does. I'll put up a video on how I checked fuel pressure on mine since TBI doesn't have a test port. If the pressure was low, my plan was to slowly pinch down on the downstream rubber test line I added to check pressure and see if the pump could increase pressure. I think that would help determine if the low pressure was the pump or pressure regulator. You can pull the plugs and maybe get an indication if it's running really rich or lean and compare that to the light flashes and codes. If you are checking sensor voltages MAKE SURE your meter does NOT have the test lead in the CURRENT (amp) port. The current port will short the computer. Checking sensor voltages is inherently risky so you have to be careful and not short the circuit. czcams.com/video/-4oCAelzrWM/video.html
TLDR: Thanks for your kind words. There are several things that could be happening and there is no guide that is going to direct you to the issue. You will have to understand the components and how they interact and figure out what issue or combination of issues could be causing the problem. Then prove that the suspect parts are the problem and fix them. This guy has this playlist showing a lot of info on car sensors and I found them helpful. czcams.com/video/XQYDwIWS6Ho/video.html
A good manual, ideally a factory service manual, will have a lot of good info specific to your truck.
Sorry for the long reply, Best of Luck!
@@PracticallyStock Really appreciate all this additional information. Bottom line like you said the more you understand where the components are and how they work the quicker the solutions. Update on my fuel pump. For this 1994 Chevy C1500 4.3L, had to put a special T strator adapter to hook up fuel pressure gage. (placed in between the fuel pump line going into the fuel filter) to read the check the fuel pump pressure. That year and model they did not put a strator valve by the engine or the fuel filter underneath the truck on drivers side It's suppose to read 9-12 PSI by the book. It read 1 psi just off the peg. I couldn't believe my eyes so I rented O'Reilly's fuel guage and it read the same of it, 1 PSI. The guy at O'reilly said the can still run on 1-2 psi around town but as you get on the road and try to pass or go up a hill it will lose power, it can't keep up with the demand. So for now I'm going to run the truck to get the tank almost out of fuel and do the dreaded drop the tank and install new pump. I hope that fixes it. But I always have your find to check if the new fuel pump install doesn't get the fuel pressure power back to the engine. What is interesting this Code 44 only says O2 fuel lean, but obviously doesn't mean it's just the O2 Sensor that might be bad, the O2 is just saying you got some kind of Fuel problem. How many different fuel problems can Code 44, 02 sensor Lean, lead to?
1 psi lol. I bet the pump and/or pressure regulator fixes that and the problem goes away. Might replace the filter as well if it seems suspect. I'd check pressure after the repair incase the new pump or regulator is defective. Hard to say how many things can cause a lean code. To my knowledge anything that actually causes a lean condition (dead cylinder, lack of fuel, bad sensor readings, ect) or gives a false lean reading (bad wirings, bad computer, exhaust leaks, wrong sensor, ect) can cause a lean code. From what I read, you have the textbook example of a lean code where there is actually a lean condition because the fuel system can't get enough fuel to the engine.
Good find!
so the problem was the female o2 sensor coupler?
I don't remember the plug type but it was the plug on the car's harness that was not making a good connection. I bypassed the signal wire around the car's plug and that fixed the signal issue