High idle issue with ICV and MS2

[BMWManiac]

The car has run great for months. Out of nowhere, it now wants to idle at 3k rpms....replaced ICV, no change. Removed ICV and now use the idle screw....idles like a dream between 900 and 1000 rpms with 5% tb adjustment....thoughts? Is there a driver or something in the MS2 that controls the ICV that could go bad?

[nightbear]

the ICV could get stuck open

[BMWManiac]

Yes, but why? They are both brand new....issue started with my old icv, which is why i replaced it

[BMWManiac]

Still no resolution...running off no ICV and opened the TB about 5%....idles great, but I'm sure in winter it will get worse

[BMWManiac]

Wanted to bump this....seems that I cannot run A/C without an ICV, so now I have a tune for summer, but would like to solve this mystery. I will reinstall my old ICV and see if the problem continues. There are no vac leaks....if I unplug the ICV, shouldnt my idle drop or will the vac flow itself force the gate open?

[Dakotademon7]

I found that if I unplug my ICV, the idle will jump up. I used a hose clamp around the vacume line to control my idle speed. I tighten it down till my idle is at the RPM I want it at.

[BMWManiac]

I found that if I unplug my ICV, the idle will jump up. I used a hose clamp around the vacume line to control my idle speed. I tighten it down till my idle is at the RPM I want it at.

Hmmm, never thought of that....so if my idle doesnt respond to the ICV being plugged in or not, and 3 x different ICVs all act the same, is the issue with the ms2 ems itself?

[nando]

I found that if I unplug my ICV, the idle will jump up. I used a hose clamp around the vacume line to control my idle speed. I tighten it down till my idle is at the RPM I want it at.

the only vacuum line is the FPR line and that controls fuel pressure. I sure hope you aren't talking about that.

if the ICV is getting power and it's not broken, it's most likely settings, such as the TPS adjustment, or the PID lockout settings. what frequency are you running the valve at? it should be 99hz.

[BMWManiac]

the only vacuum line is the FPR line and that controls fuel pressure. I sure hope you aren't talking about that.

why not just fix the system? it's either a misadjusted TPS or the ICV is bad, or the ICV isn't getting power. it's simple and elegant and it works a lot better than ghetto rigging a hose clamp.

BTW, it's not an idle adjustment screw. it's the throttle stop, and when you adjust that it throws the throttle switch out of wack.

I see....unfortunately, it is the only way to get the car to idle without the icv and with the icv, the car is not driveable. The TPS is not an e30 or E36 one, so I will see what replacement I need. If the ICV is not getting power, does that mean I either have to replace the wiring harness or EMS, correct?

[nando]

I see....unfortunately, it is the only way to get the car to idle without the icv and with the icv, the car is not driveable. The TPS is not an e30 or E36 one, so I will see what replacement I need. If the ICV is not getting power, does that mean I either have to replace the wiring harness or EMS, correct?

I edited my post because I realized you were talking about MS2 and not Motronic. still, it's a solvable issue.

the ICV gets power from the harness (from the main relay specifically). if a wire were broken it would be easier to fix it than replace the whole harness.

Most likely some setting on entering the PID closed loop isn't quite set correctly or maybe the TPS calibration is out of adjustment.

[BMWManiac]

I edited my post because I realized you were talking about MS2 and not Motronic. still, it's a solvable issue.

the ICV gets power from the harness (from the main relay specifically). if a wire were broken it would be easier to fix it than replace the whole harness.

Most likely some setting on entering the PID closed loop isn't quite set correctly or maybe the TPS calibration is out of adjustment.

I removed the protective covering and followed the wiring all the way to the firewall since that is where I would have suspected a broken wire...wires were fine!

I can take a screen shot of the ms2 PID and go from there.

The thing is, this happened out of the blue and all adjustments in ms2 worked fine for about 2 months!

[nando]

but the weather has changed. so something may not have been quite set correctly and you never noticed before. or maybe the TPS calibration needs to be re-done.

[whodwho]

Sounds like you are running CL idle, is the CL indicator coming on at idle?

I would go back to warmup mode until you get it idling again.

[BMWManiac]

At the time of the original post, the weather had not changed....it was still cold.

Im still a nood to the ems, so:

I will look into the CL idle vs warmup mode
How do I recalibrate the TPS?

I appreciate all the help. My buddy did all the initial tuning, so I am learning as much now as possible so I dont bug him as much and understand how to properly tune myself

Do either of you have optimal idle settings I could reference for a stock m20? Running 274 cam and 42 lb injectors

[whodwho]

For calibration go to Tools > Calibrate TPS

For the idle settings, start with warmup mode and put whatever is needed to set the desired RPM and can go back and try CL when you have it stable on warmup mode.

There is a recent thread on CL and some suggested settings to try.