High Idle around 1000 rpm

[Garageaholic]

My M30 is idling kinda high, around 1k rpm...I think it could be attributed to one of a couple things: (all sensors are hooked up by the way)

-Lightened flywheel

-No exhaust (just headers)

-I haven't driven the car. Just had it run a couple times for a minute or so.... so the ECU hasn't "broken in" the engine yet


any ideas?

[azzkikr]

I dont have a solution yet but I had the same problem. I ran my M30 just fine without exhaust...straight headers. Then I welded up the exhaust and attached it to the car and now it idles around 1000RPMs. I figured it was due to the backpressure change and the ECU not compensating for it yet. I ended up finishing the welding about 11:00 and I only ran the car for a minute just to see what it sounded like so I did not try to troubleshoot it at all. I am going to be in the garage tongiht so I will let you know what I find out. More than likely you just need the ECU to figure out the change.

EDIT: I did a little reading and the ECU does in fact save state. So it remembers certain settings between runs thus you do have to run it for a while to "learn" the new conditions. Just wanted to confirm that since I wasnt certain about it before.

[euroshark]

If the O2 sensor or Idle Control Valve are malfunctioning or just have dirty connections they can cause a high idle... but the lightweight flywheel sounds like it could be doing it to... Maybe adjust the speed screw on the ICV?? If you have one... My 3.2 running on the 008 motronic ECU has an adjustable one.

[bumpstop335i]

I would check if the ICV is not stuck in anyway.
I had this problem, except that it idled at around 2500rpm. I fixed this by cleaning all the goop out of the unit.

[Garageaholic]

It idles fine, just had to break it in...

[Garageaholic]

It was actually the code plug. I had a 325 super eta code plug. I put a 325i code plug an it idles right around 700rpm.. PERFECT

[JoeMadoo]

High idle was a problem for me and I found out it was a bad coolant temp switch. Instead of replacing it, i went ahead and made a switch out of it in the dash.