Rough Idle And Climbing Vaccum On Cold Start

[scratchgolfer]

Hi, Im having an issue on cold start with my 04 A4 1.8t. Ive read many threads about this but was just curious if anyone could diagnose my issue. When I cold start it (around 30 deg or colder) it runs good for about 5 sec in high idle then once the vaccum creeps up to about 8-10 it idles rough and fires random missfire codes, then after idling for about 30 sec the vaccum drops off to about 20 and then the car runs fine and is still in high idle and runs perfect until the next cold start. any help is appreciated. Thanks

[markskyline]

I'm having the same problems. If you find out anything any insight would be appreciated.


Thanks.

[blkd_outA401]

Have you scanned with Vag? Do you have a cel? What year?

[Papis]

Hi, Im having an issue on cold start with my 04 A4 1.8t. Ive read many threads about this but was just curious if anyone could diagnose my issue. When I cold start it (around 30 deg or colder) it runs good for about 5 sec in high idle then once the vaccum creeps up to about 8-10 it idles rough and fires random missfire codes, then after idling for about 30 sec the vaccum drops off to about 20 and then the car runs fine and is still in high idle and runs perfect until the next cold start. any help is appreciated. Thanks

I think i have the same problem. I have a weird buzzing noise at startup...and afterv idle climbing when driving. Maye be it's the secondary air injection pump relay that I need to change. This relay is located in the Dash (after the fuses box).

Papis
Audi A4 B6 1.8T
Automatic Trans

[mueller284]

I think i have the same problem. I have a weird buzzing noise at startup...and afterv idle climbing when driving. Maye be it's the secondary air injection pump relay that I need to change. This relay is located in the Dash (after the fuses box).

Papis
Audi A4 B6 1.8T
Automatic Trans

Did this ever get resolved? I'm having the same exact issue. Not the buzzing sound, just the vacuum/rough idle problem.

[epraia12]

Check to make sure you have no air leaks.

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