fast idle 320i

[spiderman]

Morning people, I have an 87,88 320i 4 door I am finally just about ready to put back on the road. It has sat for about 13 years in a garage, and I have replaced the fuel pump and filters etc and got it running. My question is this, when it starts it idles about 1100 rpm and as it warms up the idle speed gets higher, and when its up to temp it idles about 1800 rpm, any ideas what I need to look at. Thanks scott.

[Brianmoooore]

Large changes made in the 320i management systems made around the build date of your car. We need to know exactly what you have, although I suspect that "air slide valve" may feature in this conversation at some time.

[spiderman]

Ok, what info do you need to identify what I have.

[Brianmoooore]

Close up pics of the engine bay, last seven digits of the VIN.

[MattTheHat325]

I have this exact same issue on my 1990 325i 2 door. Mine has been pretty much a daily since 2009. I've recently replaced the water pump, thermostat and housing, cam belt, oil service, plugs, fuel filter, blue temperature sensor, intake elbow and all inlet associated vacuum and breather pipes. Only now has it started to do this, has never idled high before. Could it be loosing vacuum from elsewhere such as manifold or throttle body gaskets etc?

Brian, any guidance would be greatly appreciated!

[MattTheHat325]

Sorry Brian just going back to your mentioning of the air slide valve, I actually bought one of these at the time of ordering my hoses. After a lot of head scratching and studying real oem, I couldn't for the life of me see anywhere for it go on my car? It was featured on the blow-up doo dah on cotswold's system when my reg was entered so I assumed I must have one?

[Speedtouch]

No, they were only fitted to the pre-facelift L-Jetronic system used on chromey 320i models.

http://www.e30zone.net/e30zonewiki/inde ... lide_Valve

[jimbom30cab]

not sure if this will help or not but i had something very similar. I adjusted the 2 screws holding the TPS in place which moved it slightly and the idle returned to normal.

[Brianmoooore]

my 1990 325i 2 door.

You definitely won't find an air slide valve on one of these! Management system on a '90 car is several orders of magnitude more sophisticated than that on an early two litre.
If your car idles higher than it should, then it is getting more air than it should. As simple as that.
How it's getting excessive air is another matter. Could be something as simple as a too tight throttle cable, misadjusted throttle stop, air leak into inlet side or possibly the ICV is being held open more than it should be by an electrical fault.

[MattTheHat325]

I see, well if that ends up being the issue on yours spiderman, I've got a brand new one in the packet for you!

I'll look into the TPS, although that sounds too good to be true knowing my luck!

[Brianmoooore]

Don't just randomly adjust it, or you will end up with other faults. Check that it switches electrically, check that the throttle stop hasn't been moved since it left the factory, then set the TPS so that it switches reliably immediately the throttle leaves its stop.

[jimbom30cab]

what voltage should be supplied to the ICV during idle Brian?

[Brianmoooore]

what voltage should be supplied to the ICV during idle Brian?

Life's not that simple I'm afraid. If it were a voltage, it would be whatever is required to produce the right revs as programmed into the software, but an M20 ICV comprises two opposing coils which are PW modulated to open the ICV the required amount.

[jimbom30cab]

Is there anyway to adjust the coils or the ICV its self ?

[Speedtouch]

They can be cleaned out using carb or brake cleaner, but not adjusted as such.

[jimbom30cab]

ok, so i guess an electrical fault causing high idle could be down to an ECU defect then?

When the engine (m30b35) is hot, my idle sits at 1100rpm for a while and the drops to 800rpm by its self (there are no vacuum leaks and everything else is tested or replaced with new)

[Brianmoooore]

Nothing to adjust on the ICV. If everything else is as it should be, the ECU will provide the correct drive signals. (I'm assuming we're still discussing facelift management systems.)

[spiderman]

I hot picd taken yesterday, but can't get them on yet, but from reading the sbove I think I eill check yhe air slide valve first and take it from there.

[MattTheHat325]

Thank you Brian, first class hand-holding as usual there! I have a decent idea of what I'm trying to achieve now rather than just blindly poking around