High idle 1.2k

Mon Dec 19, 2011 8:37 pm

I've got an E30 316i with a 325i m20 engine in it. I'm currently getting high idle, sits around 1.2k rpm.

I suspected it to be the IAC valve, however tried a different one and it's the same result.
There's no splits in the major intake hoses, there's a few in some of the breather hoses however they're right where the jubilee clips sits so it pushes it firmly together.

The only thing I can think of is a vacuum leak or maybe the coolant temp sensor?

Mon Dec 19, 2011 8:51 pm

do you reckon it could be a bad intake manifold gaskets? Or throttle body gasket.

Mine does this and i'm changing all the intake manifold and throttle body gaskets as well as the blue sensor

I heard some people clean their AFMs, as the barn door can get a bit stiff.
Also, you could look at the throttle position sensor?
Maybe cam cover gasket or oil filler cap gasket gone?

Mon Dec 19, 2011 9:03 pm

When I did the engine conversion I was sure to replace the inlet manifold gaskets and the throttle body gaskets. So that can't be it.

Blue sensor is definitely a possibility.
Throttle position too.

I think it's wise to try the cam cover gasket and the filler cap as they would probably be the cheapest options.

Mon Dec 19, 2011 9:41 pm

I just read a thread about a possible purple/grey wire on the loom being fed 12v and telling the ECU the air con is on even though I don't have air con.

Could this also be a possibility? Would it really cause such an increase in rpm at idle?

Mon Dec 19, 2011 11:22 pm

Asthenia wrote:I just read a thread about a possible purple/grey wire on the loom being fed 12v and telling the ECU the air con is on even though I don't have air con.

Could this also be a possibility? Would it really cause such an increase in rpm at idle?

No clue mate

Do you reckon it could be the afm or is this disregarded at idle? But if your TPS is bad, it might be disregarding the icv or not making it function appropriately causing your high idle

There are ways to easily test the blue temp sensor. if it is easily accessible on an m20 to test in-situ however, I am unsure.

Tue Dec 20, 2011 5:23 am

http://www.e30zone.net/e30zonewiki/inde ... ug#Testing