2G Cold Start Stumble

[greddy_1700]

Hey everyone, so i recently purchased another DSM, its a 1995 TSI AWD Automatic. The car had sat for a while so I gave it a new fuel filter, plugs, wires, fluids, etc. The car originally had an issue starting, it cranked for about 10-15 seconds before firing up. I replaced the coolant temp sensor and that fixed that issue, but now I have another problem.

The car seems to stumble for 5-10 seconds on cold starts. After the car idles for that 5-10 seconds it smooths right out, and there are no more problems with stumbling at idle, or driving. There are no error codes and the car drives great, its just that first few seconds at cold starts.

Thanks for the help,

Garret.

 

[pimpy rider]

thats odd i just searched cold start myself, im having issues and was looking for ideas.
my 4g63t refuses to start cold. i have to prime it every time. it will fire once , and start eventually like they always do when the wiring to the temp sensor is bad. and once it starts, of course it runs rough for a bit because it is very lean until it warms up.
i have checked the sensor, it outputs same resistance as the known good one in my other 4g63t, wiring contenuity is good, ecu swapped out just to be sure. i dont know what else it could be. i have had this problem with 2 other dsms in the past and NEVER resolved the issue. of course my problem is not likely the same as yours, but it could be.
obviously the first thing to do is pull codes.

 

[greddy_1700]

Yeah its a very interesting problem, and I cant figure out why it would stumble so badly on cold starts, but then run perfectly after a few seconds. The car pulls strong, doesnt miss at all, idles fine when hot, and doesnt have any codes.

Im actually stumped as to what could be the cause...

 

[greddy_1700]

Turns out the coolant temp sensor was faulty. Cant believe I didnt think to check it at cold start... Anyways it works perfectly when its hot, but has an extremely high resistance value at normal ambient temps. Put another new one in and the car is running great again.