1994 Chevy s10 zr2 4.3, idles rough when warm
#1
1994 Chevy s10 zr2 4.3, idles rough when warm
Truck cranks fine, accelerates great, cruises great, runs great when cold but as soon as it warms up it the idle stutters and falls and eventually it will cut off. Stopping at stop lights or putting it in park. No engine light, I’ve changed, plugs, wires, cap, distributer(2 years), coolant temp, tps, IAC, thermostat. Nothing is helping
#2
I'm here for the party
are you saying the distributor is 2 year old?
did you recently replace these sensors?
how old is the gas?
im used to working on TBI motors and im not sure what you have but since its when it warms up it means (to me) its a bad sensor. When the engine is first started (cold), and engine speed is above 400 rpm, the system goes into OPEN LOOP operation. In OPEN LOOP, the ECM ignores the signal from the Oxygen sensor, and calculates the air/fuel ratio based on inputs from the coolant temperature and Manifold Absolute Pressure (MAP) sensors. After water temp reaches 105° or what ever temp the ecm is looking for the O2 sensor to see if its warm enough to read properly and some time limit has been reached then the ecm will go into closed loop as long as all "requirements" are reached.
that being said i would assume the CTS and O2 sensor is working properly cause you come out of "open loop". so now your ecm is looking from signals from your other sensors (IAC, MAP and TPS).
The TPS can cause Bucking and Jerking/Hesitation while Accelerating, Idle Surging, Sudden Stalling of the Engine and Sudden Surge in Speed While Driving on the Highway. and that would be the first place i start looking, click HERE to find out how to test the sensors
did you recently replace these sensors?
how old is the gas?
im used to working on TBI motors and im not sure what you have but since its when it warms up it means (to me) its a bad sensor. When the engine is first started (cold), and engine speed is above 400 rpm, the system goes into OPEN LOOP operation. In OPEN LOOP, the ECM ignores the signal from the Oxygen sensor, and calculates the air/fuel ratio based on inputs from the coolant temperature and Manifold Absolute Pressure (MAP) sensors. After water temp reaches 105° or what ever temp the ecm is looking for the O2 sensor to see if its warm enough to read properly and some time limit has been reached then the ecm will go into closed loop as long as all "requirements" are reached.
that being said i would assume the CTS and O2 sensor is working properly cause you come out of "open loop". so now your ecm is looking from signals from your other sensors (IAC, MAP and TPS).
The TPS can cause Bucking and Jerking/Hesitation while Accelerating, Idle Surging, Sudden Stalling of the Engine and Sudden Surge in Speed While Driving on the Highway. and that would be the first place i start looking, click HERE to find out how to test the sensors
#3
Yes I am saying that my distributor is two years old, I recently replaced the sensors with AC Delco, the gas is a few days old, I think a narrowed it it down to the air control valve because all of a sudden it got stuck open and now the check engine light is on and there is air sucking into the engine, so you think the IAC was not working probably even before it was stuck, to cause the stalling when warm?
#5
Troubleshooting sensors and how to test you'll find the specs on testing the IAC there. it could cause a stalling issue
#6
Troubleshooting sensors and how to test youll find the specs on testing the IAC there. it could cause a stalling issue
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#8
Yes, I’m sure it comes on and then blinks off and then back on again, another thing I forgot to mention was while I was away for school the truck set up for 4 or 5 months. I’ve replaced the gas and drove it as much as I could considering it idling so rough and shutting off, but mainly every time I have to jump it to get it going.
#9
I'm here for the party
How old is the filter?
But with any computerized engine, when all else fails check your grounds. Take them off clean them and see what happens even the battery cables.
Was working on a 89 checked everything, replaced fuel filter, checked fuel pressure. Would smoke bad and when it warmed up would most the times stall. If you tried to floor it the engine would pop and sputter but wouldn't really take off. Battery kept dying so I swapped it with the one in my 94. Started back up and pretty much noticed it starting to run better. Took it out and it ran like nothing was wrong. Swapped batteries back to the original and it was still running great. Never did find out what the issue was thinking it was a poor ground but I also added fuel.
But with any computerized engine, when all else fails check your grounds. Take them off clean them and see what happens even the battery cables.
Was working on a 89 checked everything, replaced fuel filter, checked fuel pressure. Would smoke bad and when it warmed up would most the times stall. If you tried to floor it the engine would pop and sputter but wouldn't really take off. Battery kept dying so I swapped it with the one in my 94. Started back up and pretty much noticed it starting to run better. Took it out and it ran like nothing was wrong. Swapped batteries back to the original and it was still running great. Never did find out what the issue was thinking it was a poor ground but I also added fuel.
#10
How old is the filter?
But with any computerized engine, when all else fails check your grounds. Take them off clean them and see what happens even the battery cables.
Was working on a 89 checked everything, replaced fuel filter, checked fuel pressure. Would smoke bad and when it warmed up would most the times stall. If you tried to floor it the engine would pop and sputter but wouldn't really take off. Battery kept dying so I swapped it with the one in my 94. Started back up and pretty much noticed it starting to run better. Took it out and it ran like nothing was wrong. Swapped batteries back to the original and it was still running great. Never did find out what the issue was thinking it was a poor ground but I also added fuel.
But with any computerized engine, when all else fails check your grounds. Take them off clean them and see what happens even the battery cables.
Was working on a 89 checked everything, replaced fuel filter, checked fuel pressure. Would smoke bad and when it warmed up would most the times stall. If you tried to floor it the engine would pop and sputter but wouldn't really take off. Battery kept dying so I swapped it with the one in my 94. Started back up and pretty much noticed it starting to run better. Took it out and it ran like nothing was wrong. Swapped batteries back to the original and it was still running great. Never did find out what the issue was thinking it was a poor ground but I also added fuel.