Author Topic: high idle! 93 E36 318is (Read 8270 times)

Max55 · « **on:** October 13, 2010, 01:41:43 PM »

Hey guys, its me again

Fixed the rpm crazyness with some new wires to the TPS sensor and it runs great now HOWEVER, it idles very high 1500-2000 rpm, and can vary but normally 1500rpm.

This past spring I replaced the ICV and the MAF. All fluids have been changed, I checked for vacuum leaks, couldn't find any. All new filters etc. Its not throwing any codes or anything. What could this be??!! I am at a loss!

Also related, normally when cruising and letting off the gas the MPG gauge goes way above 40mpg, now it goes barely above 40

Please help!! very hard to drive a stick with the constant extra RPM:confused::confused::confused:

DesktopDave · « **Reply #1 on:** October 13, 2010, 06:00:51 PM »

I'd guess that the TPS isn't adjusted properly, but I've never done one. I'm not sure if it's adjustable...but one many cars it can be rotated slightly to match a certain resistance value, but I'm pretty sure the e30 is just an on/off switch. Are you sure the wires you ran are correct?

I'm not trying to be a snot here, but it's my experience that most problems that crop up after I fix something are a result of something I missed (like the time I forgot to re-connect the AFM - car stalled every time I hit the gas!).

My second guess is that the car is stuck in cold enrichment. I saw this once before on an earlier pre-Motronic BMW.

Check the coolant temp sensor and the intake air sensor (in the AFM). If the car doesn't get a warm-up signal it'll never drop the idle for warmed-up running.

Max55 · « **Reply #2 on:** October 13, 2010, 06:58:21 PM »

Where is the air intake sensor? Is that different than the maf? Also is the coolant temp sensor the one that gives the reading to the dash gauge? My car is always right about in the middle. All in all these problems are driving me nuts it is always something

DesktopDave · « **Reply #3 on:** October 13, 2010, 07:35:47 PM »

I'm still thinking that TPS needs adjusted. I'll bet it's not right. Test the resistance too. You should get 5vdc on pin 1 to ground with key in position 2. Resistance between pins 1 & 3 should be about 4000 ohms. Resistance between pins 2 & 3 should go from 1,000 to 4,000 ohms as you move the throttle plate from closed to WOT.

There are two coolant temp sensors. One (rear) for the gauge, one (front) for the DME. I'm pretty sure they cannot be swapped. Bentley says it should be between 2000 and 3000 ohms cold (70degF) and about 300 ohms at operating temp (180degF). Resistance should gradually decrease as the motor warms up.

The intake air temp sensor is built into the AFM and shares the same wiring harness (FYI we don't have a MAF - those are the hot film sensors in later cars). Test it on pins 4 & 5. Just as above, Bentley says it should be in the range of 2000 to 3000 ohms at 70degF. Of course, it'll never see 180degF, so you'd be looking for higher resistance if the air temp is cooler.

Max55 · « **Reply #4 on:** October 13, 2010, 11:02:58 PM »

Dave man, thank you for your replies, this section is dead almost without you. I will test it out properly tomorrow,I tried to fiddle with it today but didnt have time to check it properly.

If or when i figure this out I will report back!

DesktopDave · « **Reply #5 on:** October 14, 2010, 07:21:28 AM »

Let us know. We'll get it sorted if you're willing to do the work.

You're welcome...just giving a little back...it's all about the cars...

I also remember when I couldn't afford manuals or decent tools, AND didn't have the web to check for answers.

Max55 · « **Reply #6 on:** October 30, 2010, 06:46:53 PM »

i just wanted to say Dave i think you were right, i took off the electric tape on the 3 wires to the TPS sensor, and one was broken off again. so i put all new clips on and taped each one individually and now it runs awesome, so far only 1 time where it barely stumbled again like it had. what would you recommend as a fix for this? as far as a permanent solution to my broken wires to the tps sensor

DesktopDave · « **Reply #7 on:** October 30, 2010, 07:08:35 PM »

If the wires aren't too short I'd do flux & solder, maybe with heat shrink tubing if it'll fit. A nice 40+ watt iron should do it really well. The little 25w jobbies won't do a good enough job with thick wire. There's a paint-on goop (liquid electrical tape) that works pretty well too, but it gets a bit hot there and I don't think it'd last. Heat shrink tube works well.