Boost loss after 1st start?

L04F127

MEMBER
2007 AUDI A4
2.0L
4 CYL
TURBO
4WD
AUTOMATIC
152,956 MILES

I have had a reoccurring issue with my vehicle listed above quattro, where when I start it in the morning it runs fine at a good 10lbs of boost past roughly 3,000 RPMs. Usually on the way to work I have to stop at a light, stop sign, ext. After doing so for some reason the turbo only produces 2lbs of boost. (Same issue accurse when I shut off the car then start it). The only way to restore the turbo to 10lbs of boost I have found is to wait roughly 3-4 hours without the vehicle running. It was running lean due to a bad PCV valve which has since been replaced but the issue still occurs.

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

This could be the waste gate not working correctly or the turbo is worn out and needs replacement. Do you have a check engine light on? If so, let's run the codes, this guide can help:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

I have also seen the air charge sensor go out and cause this issue as well. Check out the images (below). Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.

Images (Click to make bigger)