I believe my injectors on 88' T2 are leaning out in cold. On cold start mornings, I have to manually idle the car till it warms up. If the rpms drop below 1,500 the engine wants to fall on its face and die. I orginally thought this is TPS related, but I was recently told different. I've got an A/F narrow band hooked up as well, and before the engine warms, it reads lean. Very lean. But once the engine is warm, all these problems go away and I'm stoich readings in my daily driving, slightly rich in boost.

 

Of course it reads lean at start up, it's only a single wire o2, and dosen't have a heater so you can't read the ratio til it's warmed up. The wideband, (fourwire) o2's have a wire for the sensor heater, which would allow you to read the ratio when cold, although it's still usually lean.

 

Probably just needs a tuneup. Do a full tuneup, adjust the TPS. Make sure to check the water thermo sensor on the water pump housing. If it is reading wrong, the ECU can get confused during cold starts.

 

A car with a properly working water thermowax and fast idle cam setup should/will not fall on its face whent the engine is cold.

Just some FYI. If your car has a airpump and working ACV, it's normal for the 02 sensor to read lean at idle. Theair from the airpump goes to the exaust ports. The exaust ports are located before the 02 sensor so it stands to reason that the 02will SHOW lean at idle.

That DOES NOT mean the mixture is lean, if you follow my drift.