High idle issue with ICV and MS2

[BMWManiac]

One day my idle jumped to 3k rpms! No settings or changes would work. I had my idle running for a year off the adjustment screw. Another member building his e30 had the exact same problem and returned his MS2, where they found the culprit. I sent my ECU to PFTuning and had them specifically check this out and he verified the issue. Returned ECU and I now use my ICV!

[nomansland92]

How did you find out it was bad and how did you have it fixed, I'm having issues with my icv also but my valve just doesn't respond to ms at all. With it plugged in but out of the intake I can freely move the value with my finger and no settings seem to change it but with the stock ecu it snaps shut.

[BMWManiac]

Just wanted to close this thread....turned out to be the MS2 unit. Another member had the same issue and found out it was an issue with a faulty transistor - U8! Just got my MS2 back, reinstalled ICV, and good to go!

[whodwho]

Not necessarily that you should but you need a stable idle first if you do

[BMWManiac]

All right, so this is my plan as of right now.

1. Reinstall ICV
2. Return set screw to 0% and calibrate TPS
3. Start car and make sure car is in warmup mode (my tune is for PWM warmup already and not CL)

Are you saying once my PWM warmup idle is good that I should switch it to CL?

[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.

[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]

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.

[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.

[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]

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]

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 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]

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?

[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.