question about idle

[wang540]

I just got a 1990 525i 5 speed with just under 200,000 miles but the motor was rebuilt and a new clutch was put in.

When i let the car sit in idle the rpms go up and down like im hitting the gas and letting go. It does this when i first turn the car on but if i put it in gear and drive for a bit and then stop, it idles like normal. Im just wondering if this is a problem and if it so what could be wrong?

[Jay 535i]

Mine does that too. The revs fluctuate between about 800 and 1500 right after a cold start. After a couple of minutes, or after a warm start, it settles right down.

Dunno why.

[wang540]

This is my first manual car so i don't know if it has to do with that or if its just because its cold out.

Also when im going about 25+ MPH it sounds like there is wind rushing into the car and its quite annoying. Im just wondering what could be the cause of that?

[octanejunkie]

I had a similar problem on my 535. Try taking off the idle stabalizer valve and spraying it liberally with carb cleaner or brake cleaner. They get a bit gummed up and can be sluggish until the engine warms and frees it off a bit. Also, clean around the throttle butterfly. Hope this helps.

[Kakaire]

Mine used to do that each start from cold and sometimes it used to stick causing a high idle speed. After cleaning it stopped hunting. Good luck.

[grave77]

u have few problems ... ur engine got inlet leaks from the rubber parts .. so make sure everything is tight on. the regulator valve might be stuck so remove it and spray in W40 rotate around the axis so you would hear it flipping inside then replace it back. the small hoses connected to the fuel regulator always get dry and causes vaccume leaks. what's the engine type? M20 or M50? M50 is the Black 24V engine M20 is the metal older type.

[wang540]

u have few problems ... ur engine got inlet leaks from the rubber parts .. so make sure everything is tight on. the regulator valve might be stuck so remove it and spray in W40 rotate around the axis so you would hear it flipping inside then replace it back. the small hoses connected to the fuel regulator always get dry and causes vaccume leaks. what's the engine type? M20 or M50? M50 is the Black 24V engine M20 is the metal older type.
__________________

I dont know what kind of engine it is sorry and also this morning i got a warning that said something about the oil pressure sensor. Is that soemthing that should be fixed right away or can it wait a while?

[grave77]

ok if ur engine looks black with a plastice cover, then its M50 engine, else its an M20 and I think it's an M20 since ur car is a 90 model. pressure sensor should be changed cuz this tell syou about the oil condition when engine runs, also tells when oil pump fails that saves ur engine from a cracked crank or camshaft, head ..etc ... it's not a tough job to change it.

[Jay 535i]

u have few problems ... ur engine got inlet leaks from the rubber parts .. so make sure everything is tight on. the regulator valve might be stuck so remove it and spray in W40 rotate around the axis so you would hear it flipping inside then replace it back. the small hoses connected to the fuel regulator always get dry and causes vaccume leaks. what's the engine type? M20 or M50? M50 is the Black 24V engine M20 is the metal older type.

Any chance you could provide pics or point to more detailed instructions? I don't know what half of those items are, let alone knowing how to remove and clean them.

Is this stuff in the Bentley manual?

[wang540]

Any chance you could provide pics or point to more detailed instructions? I don't know what half of those items are, let alone knowing how to remove and clean them.

Is this stuff in the Bentley manual?

Yeah he's right, that would be pretty damn helpful if you could.

[grave77]

its in bentley manual, but I will look up some pics and edit them for u ( add some arrows )

[wang540]

Thnk you

[grave77]

if you looked at the picture

http://www.bimmer.info/forum/attachment.php?attachmentid=1888&stc=1

Number 2 is the idle regulator valve that you need to remove and spray to make sure its freely rotating or flipping you will see a moving part inside that closes or opens the path between the 2 hoses connected. hope this picture would help. for M30 engines on 535i it has the same part but located above the engine.

[FWinNH]

All 1990's were M20. So unless it had an engine upgrade...

[Jay 535i]

Thanks.

Wish you had a pic for my M30. All those black doo-dads look the same. :(