2.0L M52TU - Struggling/stalling on cold start

[Space_coyote]

Hi all, wondering if anyone has thoughts here before I head to a mechanic... Only when starting cold my Z3's engine (Dec'99 2.0L M52TU manual) struggles and often stalls if I try to drive off before the engine temp needle gets to the middle of the ‘blue’ part of the temp gauge. If I leave it to just 'do its thing' while warming up, the revs go from about 800 upto 1100 and then drop back down to 800 once the middle of the blue part of the gauge is reached. It does this without any accelerator input. The whole process only take a min or two, and then it's fine to drive off without struggling or threatening to stall. I’m curious if anyone knows what might be going on or if this is common/normal.

 

[t-tony]

If I recall correctly you're in Australia? Do you have a code reading device?
My 2000 2.0 Z3 (1991cc) had an OBD port under the dash on the righthand side. This only gives access to Engine and Auto. Trans ECUs, all others are accessed through the round port under the bonnet (requiring the use of an adapter cable to connect).

Tony.

 

[colb]

As @t-tony says get a decent code reader on it and see if it's set any codes, your symptoms usually as a result of air leaks in the vaccum system, check all rubber pipes and intake boots on the engine for holes or splits replace any you find. A dirty sticking idle control valve is also a possibility, spray carb cleaner in this to clean it.