Idle FAQ a fix for hunting idle on '89 525m?

[Gene in NC]

http://www.geocities.com/bmw535i86/text/idle_FAQ.html

FAQ claims to apply to pre Motronic 1.1. Works on our '87 325is with Motronic 1.1. However, IIRC, I had to connect the ICV and "adjust" the hole size in the penny a bit.

See "penny fix" under KLUDGE.

Real Q is whether penny kludge might work on '89 525 manual with Motronic 1.3. Idle on '89 is low and hunt drops it lower. AC on raises the idle, as it should, and prevents stall. However, makes clutch engagement tricky in low, because rpm not easy to control/predict and I'm not much for girlie over rev on low gear clutch engagement.

[Tiger]

Do the basic diagnostic to find out why it is idling low. Not some patchwork. Alot of time this is caused by MAF. ICV needs to be cleaned too.

[Gene in NC]

Been there done that. Swapped in known good MAF, and cleaned the heck out of ICV.

Code now is 1252 (injector group 2) in Motronic 1.3.

Tail pipe is sooty, but mileage seems to be normal. No extended highway miles since CPS replace.

AC on increases Idle speed and tends to steady but eliminate hunting.

[tim eh?]

But our ICVs don't have an adjustment screw (do they?)

My ICV was dead, no amount of cleaning helped. All went well after I replaced it. The giveaway was that it made no noise at all, the new one makes a high pitched whine but it is difficult to hear as a seperate noise over the engine but you'd hear it better with a screwdriver to it and your ear.

My symptoms were different. Rpms would fluctuate at idle from just over 500 (where it would sometimes stall with no gas) to around 1000rpm in a regular pattern of around 1.5 seconds.

[BennyM]

But our ICVs don't have an adjustment screw (do they?)

My ICV was dead, no amount of cleaning helped. All went well after I replaced it. The giveaway was that it made no noise at all, the new one makes a high pitched whine but it is difficult to hear as a seperate noise over the engine but you'd hear it better with a screwdriver to it and your ear.

My symptoms were different. Rpms would fluctuate at idle from just over 500 (where it would sometimes stall with no gas) to around 1000rpm in a regular pattern of around 1.5 seconds.


Actually, the ICV will make its buzzing noise with the key in position 2, but without the engine running. Than it's much easier to listen to it.

Tim, did the fluctuating idle get worse after you blipped the throttle?

[tim eh?]

Actually, the ICV will make its buzzing noise with the key in position 2, but without the engine running. Than it's much easier to listen to it.

Tim, did the fluctuating idle get worse after you blipped the throttle?

No it always was exactly the same. Only happened on cold starts (+/-15'C and colder) and exactly like I described every time. I would blip the throttle at the bottom of its cycle and it would cough or stutter (or stall) and then go straight back to exactly the same pattern. The car would do this only 30 seconds to a minute before the idle became smooth.

Yeah - check ICV for buzz with engine not running gee once again I feel like I missed an easy one. :D

[Gene in NC]

My hearing not so good, but can feel vibration in ICV. Can there be a problem with power level within the pulse frequency?

[eaglecomm]

OT: Gene, sent you a PM on another board.. we are getting together in Raleigh on Labor Day weekend if you are interested to meet with some other E34ers. PM me if interested.