Idle Problems

[tbernd]

Hello,

I'm a bit puzzled about the idle speed of my 350i.
In winter I changed the valley gasket an everything seems to be fine except the idle speed. The engine starts without any problem but the idle speed increases to about 1500 rpm, there it stays until the engine has warmed up, the it goes down to 1200 rpm but not lower. The idle speed screw at the plenum is screwed in completely.The engine is running stable but with too high idle. Any Idea wwhere the fault may be.
Another mysterieous problem is that when I connect the rev counter the idle speed goes up and down and after some time the engine dies. Without it's no problem.
It would be great if you have some Ideas.
Thank you.

Best regards

Bernd

[adam quantrill]

Flapper or hotwire air meter?

Either way, suspect an air leak allowing air in, breather hoses etc. Spray WD40 or similar around them and you'll hear the revs rise when you find it.

[tbernd]

Hi,

it's a flapper.
I sprayed everthing, engine running, with brake cleaner, no result.

Greetings

Bernd

[Wedg1e]

Is the throttle plate closing completely? It could be something daft like the bonnet pressing down on the throttle cable when you close it.
If the revs are still high with bonnet open, make sure all the linkages are free - if necessary disconnect the cable. Another possibility is that the cable is fraying and snagging on the inside of the outer sheath.
If the throttle's definitely closing properly and the gap is adjusted correctly by the stop screw then you may have a leak between the inlet manifold and the valley gasket, under the manifold where your spray isn't reaching.

[Danny Hoffman]

Air can leak around the idle control screw, have you tried putting your finger over it to seal it?

[tbernd]

Hi,

thank you for your good Ideas. Maybe the throttle isn´t adjusted correct. I´ll try it tomorrow.

Kind regards.

Bernd

[honestjohntoo]

Also, check your throttle return spring is correctly located and snapping the throttle plate fully shut.

If metered air is leaking thro the system and raising the idle speed, the idle speed control screw has no hope of doing its job.

Same might happen if the overrun valve is jammed with a piece of debris

Ditto - if the EAV is not fully closing - lets say because the internal bi-metal heater coil is faulty or the electrical plug is disconnected.