Idle Issues - Tune Up Attempt FAIL

[DesktopDave]

So I replaced the ICV hoses today and tried it out. The idle started out the same, but after a few minutes it stopped surging up and down. It stays pretty steady at around 700 rpm but it still idles really rough and I can smell a lot of gas in the exhaust fumes.

There's no more check engine light, and the stomp test reveals 1444.

I also tried disconnecting the neg. battery terminal for a minute to see if I just needed to also reset the thing. It still idles really rough and burns rich.

The new intake boot should arrive tomorrow or Monday, I'll see if that fixes it once and for all.

The car should run pig rich if it's a cold start. Warm starts shouldn't be like that. Seems to me that every Bosch Motronic has difficulty with maintaining idle. Mine tends to lope 600-1200 if I'm sitting in traffic. BMW also issued an inline resistor pack to solve the a few running problems on the older M42. It should be installed between the AFM and the original AFM harness connector. Hot starts and idle were improved IIRC.

Do you have access to a vacuum gauge? They're kind of an old school method to diagnose pressure leaks, but it'll tell you a lot about a motor if you know how to read them. Be sure to connect it to the intake manifold. It has to be after the TB to function accurately.

Speaking of TB...have you checked the clearance of the throttle plates? Is the throttle cable cracked at the plastic adjuster ferrule? BMW issued a fix for those plastic adjusters - it's a small steel clip to hold the throttle cable together.

[SLCE30318is]

Hm good points. I haven't checked the throttle plate clearances since cleaning the throttle body and putting it back on. I'll check that tomorrow.

If the idle problems persist after the new intake boot, I'll look into trying to borrow a vacuum gauge from our family friend that's a mechanic.

[SLCE30318is]

After checking the leaks using the carb cleaner, I finally just ordered the BMW part for the 90 degree hose that goes from the ICV to the engine as well as a new throttle body gasket.

As I was taking out the throttle body gasket, I realized that I had pinched that little hose from the engine to the bottom of the throttle body. DOH!

After cleaning all of that up and using the BMW 90 degree hose, the idle runs a lot more smooth.

However, it does still surge a bit between 700-900 rpm and the check engine light comes on during these times. It immediately goes away upon revving the engine up though. I can live with it at this point though, especially if I'm looking towards an engine swap, possibly in the near future.

Thanks again for all of the help and suggestions. I'll be posting up a thread seeking some more advice on having a shop do an oddball engine swap (F22c).