Was driving home tonite and the check engine light came on. Decided to pull codes. Came up with current codes as P1406 and history codes as 1640. Plus the boost gauge was only hitting about 4psi. The car currently runs like crap and I know part of it is that I have a collapsed lifter but nothing compares to the way it was running tonite. Also when idling I hear a hissing noise coming from the egr valve. Anybody have any ideas.

I'm not as familiar with the S2 codes. Can you use Techinfo and post the definitions for your own codes for us?

P1406EGR valve pintle position circuit P1640 QDM1 failure

Thanks.....EGR will usually be a replace. Try a wrecker, they're expensive. You might try cleaning it first.

QDM1 is typically a BCS on a supercharged car. Try the boost bypass trick, and you should see full boost again. If you do, replace the BCS. It can't be the BCA as that device has no feedback to the PCM.

What'* the boost bypass trick?

Search on boost bypass.. I think it'* merely unplugging a vacuum line.

On the EGR.. pull it off when cold...make sure it'* cold..those babies hold heat forever.

Then spray inside with carb cleaner and gently work the pintle valve until it does not get stuck.

yeah i found what i was looking for. I'm gonna go out this morning and mess with things and see what I come up with.

well i cleaned my egr and that seems to help. I did the boost bypass trick and my boost started out at 6psi and aftering the car warmed it was down to between 2 and 4psi. Ok what next. I'm about to go sell this car if I can't figure it out cause i'm not sinking a bunch of money into this project.

Hold on a sec, these are easy problems to fix, don't cost much, and are extremely reliable.

Lets see what we have now:

Do you still have a code? Can you clear them and start over? If the bypass trick is still short on boost, make sure you did it right, then start looking for a vacuum leak. Particularly the vacuum line that runs under the nosedrive on the S2 L67. You may only be INDICATING low boost.