Greetings all! Son just got his license recently and picked up a '98 Cherokee for his first car. Seemed to run fine initially, thought all was well. Then it would be idling fine and out of the blue get very rough, rpm's would drop and it would come close to stalling out. It would run like this for a few minutes and then recover and idle fine.
He was out on the road in traffic when this happened, and the car started to run very poorly, lost all sorts of engine power, so he tried to compensate by stepping on the gas, and it bucked resulting in a fender bender. I read that the Idle Air Control motor can do this so I took it out and cleaned it, put it back in, seemed to do the trick.
Next the water pump goes, so I install a new one today and while I have it idling, the same thing happens, smooth and then very rough out of the blue. This time I can clearly hear that the IAC motor has moved to limit the airflow into the throttle body and that's the reason for the poor idle. Took it for a ride myself then and it ran so poorly, I turned around after 100'.
Does anyone know how I can determine if the IAC is getting a false signal to limit the air flow or if the IAC itself is bad and doing this?
I should also add that I hooked up my SCAN tool to the Jeep as the check engine light was on, said that 02 sensor voltage was high bank 1 sensor 1 but the odd thing is that when I went to look at the waveform, I couldn't see anything. No other sensors were available to look at, just the Absolute Throttle Position. I doubt it's supposed to be this way as on other cars I can see Coolant Temp, Timing Advance, RPM, Intake Air Temp, etc.
Any thoughts on this would be VERY much appreciated as it really is a safety issue and the car is unusable as is because there's no way to know when it's going to happen... Keep in mind that it idles and runs fine most of the time. Thanks in advance!
He was out on the road in traffic when this happened, and the car started to run very poorly, lost all sorts of engine power, so he tried to compensate by stepping on the gas, and it bucked resulting in a fender bender. I read that the Idle Air Control motor can do this so I took it out and cleaned it, put it back in, seemed to do the trick.
Next the water pump goes, so I install a new one today and while I have it idling, the same thing happens, smooth and then very rough out of the blue. This time I can clearly hear that the IAC motor has moved to limit the airflow into the throttle body and that's the reason for the poor idle. Took it for a ride myself then and it ran so poorly, I turned around after 100'.
Does anyone know how I can determine if the IAC is getting a false signal to limit the air flow or if the IAC itself is bad and doing this?
I should also add that I hooked up my SCAN tool to the Jeep as the check engine light was on, said that 02 sensor voltage was high bank 1 sensor 1 but the odd thing is that when I went to look at the waveform, I couldn't see anything. No other sensors were available to look at, just the Absolute Throttle Position. I doubt it's supposed to be this way as on other cars I can see Coolant Temp, Timing Advance, RPM, Intake Air Temp, etc.
Any thoughts on this would be VERY much appreciated as it really is a safety issue and the car is unusable as is because there's no way to know when it's going to happen... Keep in mind that it idles and runs fine most of the time. Thanks in advance!