m50 high erratic idle

[e30ftw 410]

NOOB when it comes to M50's have had a search around and can't find anything useful.

Basically motor runs. The idle is Veery high, sits between 1500rpm + going up then cutting off and droping down again then back up to around 2200rpm. After leaving it a while it will shoot up over 3000rpm.

What I have done so far is replace the hose from FPR to the intake manifold. Change vacuum hose from PCV oil breather to intake manifold. There aren't any other small type vacuum hoses I can see, so other than that looks like the only ones are brake booster and ICV hoses, PCV etc.

Fuel evap line is blocked off.

Have tryed running it with the brake booster line blocked off, Made no difference.

I'm about ready to pull the intake manifold off and replace every damn seal / gasket and hose.

Will upload video soon.

Video:

http://www.vimeo.com/10129695

Edited March 13, 2010 by e30ftw

[Forrest 35]

I suggest before you start taking it apart, wait for someone to give you advice otherwise you will be doing double the work if it could just be something else. Measure twice, cut once....

[*Glenn* 854]

I suggest before you start taking it apart, wait for someone to give you advice otherwise you will be doing double the work if it could just be something else. Measure twice, cut once....

+1

[e30ftw 410]

Wasn't meaning I was actually going to.

Bu lack of advice or anyone knowing WTF is going on = gotta start somewhere.

[mark247 39]

Does it ever settle down?

When I first put mine in whenever I would turn it on it would rev up to about 2200rpm and sit there or go up and down up and down for about 20 seconds then would flatten out and idle fine. Finally figured it out, and it was the TPS. Just changed that and it worked fine. Try unplugging it and seeing if it makes any difference.

That revving seems to be just a bit too crazy for just a vacuum leak, but I'm no pro.

[e30ftw 410]

Nah it gets higher and higher then hits and stays at 3500rpm. I tryed heaps of things now and couldn't figure it out.. unplugging TPS didn't do much from what I remember.

[Docile 64]

umm happened to me. throttle line was snagged. and was taken out of the holder thing. mine would just stay at 3k rpm and would not go down. re seated the throttle cable and it was all sweet again.. different to your one dropping and going up though...

[e30ftw 410]

Nah, my throttle is remaining closed at all times so it is not the throttle cable being too tight or stuffed or anything.

I've tested the TPS now and it's working correctly as per the Bently..

Edited March 14, 2010 by e30ftw

[*Glenn* 854]

Was the motor running / driving properly before you brought it ??

[pureboiracer 0]

sounds like airleak to me, or maby tps or something similar,

edit just checked vid. doesnot sound like an airleak. check tps maf sensor, also mabey issue in the ecu. but it definalty seems something computer or sensor related.

Edited March 15, 2010 by sydwayz e30

[*Glenn* 854]

The problem is unmetered air. Manifold vacuum will be siltch. Either the brake booster vacuum line or crankcase ventilating system has been compromised or items that should be there have been removed on the conversion.

[e30ftw 410]

The problem is unmetered air. Manifold vacuum will be siltch. Either the brake booster vacuum line or crankcase ventilating system has been compromised or items that should be there have been removed on the conversion.

No. As said, I blocked of brake booster line and it did the same - eliminating brake booster being the leak.

TPS tested out fine.

All items are there the PCV system remains, the only change was fuel evap delete and that line is blocked off into the throttlebody.

The issue is ICV. I blocked it off and the car runs with throttle slightly open. If throttle closed car dies.. But I can get it to idle fine with foot on the throttle. Revs fine etc now.

But have now found an even bigger problem thats nipped me in the butt..

[pureboiracer 0]

not quite, you really should listen to glenn you know.

i suspect the icv is just making it go crazy because the computer detects a fault somewhere and is trying to rectify it by making the icv go crazy, it may be possible that the icv is f**ked but i dont think that would be the case. but hey you never know. icvs dont usualy have that sympton when they play up, i think there is another fault and the ecu is using the icv to try and rectify it.

[e30ftw 410]

Well hey I'm not too worried at the moment. Have to take it all completely apart now anyways.

Not good..

[tire 10]

^Wheres that? Coolant leak from the HG?

[mark247 39]

Stink about the headgasket leak bro.

You can just remove the ICV, Troy did on his one and just blocked it off or whatever and his car literally idles perfectly.

[*Glenn* 854]

The problem with the running issue is "unmetered air"

Have you got a better picture of the coolant leak ?