Rough cold starts

[nolig2278]

starting is very rough, usually starts and stalls at least once. this is only on cold starts. i have to hold the throttle open to get her going and she often sounds like the vaf flapper is slamming shut. it is a tough little battle to get her going for the first couple minutes, then she runs great.

i recently readjusted the tps sensor and it reads the correct voltage. idle sensors are currently disconnected so this might be the case but I seem to think not as the car does hold idle after it is warm.

[andy]

Thats easy to test, just plug the sensors back in and see how well it starts and idles.
The other thing to try is disconnect the battery, which will clear the ecu, plug the battery back in, start and and let it relearn to idle. do this on a cold motor.

Andy P. 93 GS 1.8T

[rebel2k4]

starting is very rough, usually starts and stalls at least once. this is only on cold starts. i have to hold the throttle open to get her going and she often sounds like the vaf flapper is slamming shut. it is a tough little battle to get her going for the first couple minutes, then she runs great.

i recently readjusted the tps sensor and it reads the correct voltage. idle sensors are currently disconnected so this might be the case but I seem to think not as the car does hold idle after it is warm.

You answered your own question. What do you think the idle air control does? It bypasses the throttle budy and allows more air in when the engine needs it (i.e. when cold). any valid reason for disconnecting it? I never would, thats pointless. this is where a lot of drivability comes from, a stable idle and start up no matter the conditions.

if you remove this, you're going to have a worse idle. why would you even disconnect it?

[nolig2278]

i dont think it was working correctly and that is why i disconnected it. i had been trying to ground it out. I understand it can stablize idle but would this prevent the car from starting up ok? car idles fair after it is warm.

i will try tomorrow to reconnect it. i am still verifying that everything is connected to tbe bpt ecu properly.