Rough idle and decels in first gear

[takedown8]

I think I know what the problem is, but I wanted to confirm with people. 80% of mornings, I start the car, and it revs up to 1500rpms and then suddenly drops down to 500rpms and vibrates a little for about half a second and then comes back up again. This just started about a month ago. And then I noticed that in low gear (first gear) on my steptronic, after I come off of the gas pedal, the car slows down very quickly so much so that I jerk forward a little bit (almost like I pressed on the brake moderately hard).

I suspect this is the DISA valve similar to what other members including IMZ4N have experienced. Will be bringing it into the dealer soon, but just wanted to confirm it with you guys. Also, I'm really busy for the next couple of weeks. If it is the DISA valve, will it cause any serious damage if I don't get it fixed for another few weeks?

Thanks guys.

 

[takedown8]

No responses, eh? I thought at least IMZ4N would say something. Oh well.

 

[Caddyshk]

No responses, eh? I thought at least IMZ4N would say something. Oh well.

This is a comedy forum, not a car forum :lol:

 

[IMZ4N]

No responses, eh? I thought at least IMZ4N would say something. Oh well.

Sorry , I just saw the thread. Sounds like the same thing I had. Mine was sooo bad that I did not get the rapid slow down. This works with the vacume advance system. The flapper valve must be failing tuwards the damper. Mine was failing away from the damper. I did notice the return of power and the engine was working much better after the fix.

 

[IMZ4N]

takedown8,

Did you ever get you issue figured out?

If not , have a look at the intake hose. Just had mine replaced and what a difference.

http://www.z4-forum.com/forum/viewtopic.php?f=3&t=4393&p=62110&hilit=intake#p62110

 

[takedown8]

Ah! Haven't had a chance to bring her in yet. That's a good find though. I'll suggest that as a possible cause when I bring it into the dealer.

I'll update this thread afterwards to let you know what they found. Thanks, IMZ4N!