318ti with DASC low idle until warm
 

Hello everyone,

I am a BMW enthusiast who just acquired a low-mileage 1999 318ti with DASC. The car also has NickG Stage 3 installed. It runs great EXCEPT when being started from cold. The idle is steady but just too-low (around 600-700 rpm). Problem is worse if I turn on AC which puts additional load on the engine and RPM drop even more. Once the car warms up, everything is good. I checked codes, found none. The car also has a SAP (secondary air pump) simulator installed (SAP was deleted). I checked its operation/wiring and it is working as intended with no CEL.

Any insight into how I can improve the idle when cold would be much appreciated. The car is really nice and fun to drive so definitely want to get this sorted out as we plan on long-term ownership.

Thank you very much in advance.

Bart

I hope someone can help me...

I cleaned the IAC, replaced spark plugs, checked for codes (none). As it got cold outside, it is harder to start the car as it just idles too low when it is cold. Once it warms up, everything is great but I think the idle needs to be over 1k when you first start when really cold outside and it seems the idle is around 700-800 rpm regardless of outside temp.

I would really appreciate any insight into this. My son uses the car to commute to school and I worry that one day he won't be able to start the car.

Hello Bart....i am not a mechanic so this is not based on first hand knowledge of the systems. However i did have a similar issue and the mechanic disconnected and cleaned the throttle position sensor.. After reinstallation, the idle was at the correct rpm level and smooth. Not sure if or how the temperature would affect it, but it might be easy to give it a try. Good luck.

Thank you. I will definitely have this checked. I also was reading here that the PVC or CCV may be clogged/defective so I ordered a new one. I hope between the TPS or the PVC I can finally sort this out.

ever refreshed the oxygen sensors? pre-cat would be my first one to change, mesures the air/unburnt fuel ratio. the second one is to confirm the cat is doing it's job correctly, check the connection wires first, could be something there.. or else , test for an air leak, gently spray some break cleaner around the intake hoses and manifold while the engine is running, engine will suck it up if theres a leak and will rev. good luck

An update...

I changed the CCV which was unnecessary I think as the old one looked fine. Installed a set of new plugs which was much needed as the old ones (original?) were completely worn out after 70k miles. I looked at the maintenance records and noticed that the TPS was changed by prior owner so I did not change it. I cleaned the idle control valve. There was no idle change. Idle too low. Crap.

Then, I went to the engine bay and LIGHTLY tightened the throttle and Cruise Control cables so there is no slack. Low and behold - the idle is now rock steady at start-up and when the car warms up and does not drop and want to die when the car is in gear or AC kicks in. The idle is about 750-800 rpm regardless of the load which is great - the car no longer feels like it wants to die when starting from cold.
Looks like this solved the problem. There is no check engine light or no codes.

Thanks everyone for suggestions. Glad to put this to rest before winter sets in.