Surging Idle on 82 928
10-07-2013, 09:55 AM
#1
Instructor
Thread Starter
Surging Idle on 82 928
Hello!
I've searched the forum, but couldn't find anything that quite matches the problem I am experiencing.
I have an 82 928 automatic. I recently did some work on the intake system, including fixing a throttle body air leak, replacing the MAF with a rebuilt unit, and adjusting the aux air regulator. After doing all this, the car is running great. Except....when I have the idle switch on the throttle body connected, the idle surges under many conditions. The extent of the surge varies, depending on the temperature of the engine, whether it is in drive verus neutral, and whether the car is moving or not. (For example, with the engine at normal operating temp and sitting at a stoplight with the car in drive, it will not surge. However, when the vehicle is moving and my foot is off the accelerator to slow down, then the RPM surge. And it will also surge at colder temps when stopped and in neutral.)
If I disconnect (electrically) the idle switch on the throttle body, then the surging completly goes away. I have the idle speed at normal operating temp adjusted to 750 RPM in neutral (with AC off), and it remains consistent whether or not the idle switch is connected or not.
So, for now, I am driving around with the idle switch disconnected. But I am wondering if the surging when connected is a sign that I haven't adjusted something properly after the intake system work I did, or what might be causing this. I did not adjust the internal electrical swing arm in the rebuilt MAF after receiving it, since it tested in-spec per the WSM. I did attempt to adjust the mixture via the set screw in the MAF body (with the O2 sensor disconnected), but honestly that seemed to have very little effect.
Thanks!
I've searched the forum, but couldn't find anything that quite matches the problem I am experiencing.
I have an 82 928 automatic. I recently did some work on the intake system, including fixing a throttle body air leak, replacing the MAF with a rebuilt unit, and adjusting the aux air regulator. After doing all this, the car is running great. Except....when I have the idle switch on the throttle body connected, the idle surges under many conditions. The extent of the surge varies, depending on the temperature of the engine, whether it is in drive verus neutral, and whether the car is moving or not. (For example, with the engine at normal operating temp and sitting at a stoplight with the car in drive, it will not surge. However, when the vehicle is moving and my foot is off the accelerator to slow down, then the RPM surge. And it will also surge at colder temps when stopped and in neutral.)
If I disconnect (electrically) the idle switch on the throttle body, then the surging completly goes away. I have the idle speed at normal operating temp adjusted to 750 RPM in neutral (with AC off), and it remains consistent whether or not the idle switch is connected or not.
So, for now, I am driving around with the idle switch disconnected. But I am wondering if the surging when connected is a sign that I haven't adjusted something properly after the intake system work I did, or what might be causing this. I did not adjust the internal electrical swing arm in the rebuilt MAF after receiving it, since it tested in-spec per the WSM. I did attempt to adjust the mixture via the set screw in the MAF body (with the O2 sensor disconnected), but honestly that seemed to have very little effect.
Thanks!
10-08-2013, 10:26 AM
#5
Instructor
Thread Starter
Good morning. I checked temp 2 sensor, and it is good. Resistance measures within spec. And the engine dies when I disconnected it. So the connector and wiring is good.