Why are my car revs hunting at idle?
On idle the engine in my car is hunting and not staying at a consistent rpm. Under load the car is fine and the revs rise and fall as they should. It even stays ok when I shift into neutral for a brief moment after being under load. But if I were to stop with the engine running, within 30-60secs again the revs will not be stable.
What should I know about BMW E30 idle speed?
This article is intended for you to learn a little something about your car, and at the same time, point you in the right direction towards fixing that erratic idle. Keep in mind that this article is specific to the 1987 through 1991 E30 6 cylinder cars, however the basics apply to nearly all BMW’s.
Are there any problems with the BMW E30 3 series?
Click here to order! One of the most common glitches on the BMW E30 3 Series is an erratic engine idle. Have you noticed that the idle seems to surge constantly?
What causes an engine surge when the ECU is off?
If closed TPS voltage changes, the ECU may assume that your foot is on the throttle, causing a richer fuel mixture to be delivered. This can also be caused by a faulty TPS, or even a poor ground. With the engine off, check TPS voltage with the accelerator pedal relaxed. Then work the pedal a few times and see if the voltage changes.
If closed TPS voltage changes, the ECU may assume that your foot is on the throttle, causing a richer fuel mixture to be delivered. This can also be caused by a faulty TPS, or even a poor ground. With the engine off, check TPS voltage with the accelerator pedal relaxed. Then work the pedal a few times and see if the voltage changes.
What happens when engine idle speed is above programmed range?
When the engine idle speed is either above or below the programmed range, the ECU prompts the ISC to either increase or decrease bypass airflow. Naturally, as the IAC prompts the throttle plate to open, engine speed increases. The IAC features a plunger mechanism that may be stuck/sticking.
Why does my ECU think my foot is on the throttle?
Any deviation in throttle shaft position (due to shaft wear) will create uneven signals to be generated by the TPS reacting to this deviation. If closed TPS voltage changes, the ECU may assume that your foot is on the throttle, causing a richer fuel mixture to be delivered. This can also be caused by a faulty TPS, or even a poor ground.