Acceler8

I was cruising home from work and punched it to pass some slow moving traffic on a hill. around 5k rpm the car felt like it was lacking in its initial pulling power. Im wondering if this is caused by a misfire or my cats are starting to go bad. My CEL came on and I havent been able to check it. its going to the shop on thurs but I wanted to know if any of you have had similar issues. The car has 87k miles on it and the TB/WP/THERMO service has not been done yet could this be causeing my problems?

mclarenm8d

There are two stages to the variable intake manifold, one at ~3000 RPM and the other at the approximate RPM you mention, high 4000's (???).

Might be as simple as vacuum tubes or the solenoids that open the vacuum tube circuits being amiss in the variable intake manifold, variable valve timing system.

What causes a loss of power for me at that RPM is that the 'dag bern AC compressor is still applied ... but that doesn't cause the CEL.

ryoung

Unless you were at 130+ mph, you were in either 2nd gear (60 mph) or 3rd (88 mph). At 5k rpm, though, the engine should be feeling like it's on it's sweet spot. Perhaps something as simple as a fouled spark plug is causing both the misfire and CEL.

<img src="http://pictureposter.audiworld.com/17157/speed-in-gear.jpg">

Acceler8

I could be mistaken on my gear, I was in auto, but Im dont really want to aggravate the issue by trying it again. I will pull the plugs tonight.

do you think a plug can go bad at 10k miles?

Acceler8

Im assuming they are exteral and fairly easy to locate. The solenoids, I have no idea what they are. I was thinking maybe a bad coil pack, or at least hoping something else that was easliy replacable.

mclarenm8d

The solenoids are usually easy to find as well, attached with light brackets off the engine and in the same general locations as the vacuum tubes. If you take the main plastic cover off the top of the motor, there will be several diaghrams (sp?) and tubes in the front of the motor, in the valley area between the heads. You may be able to see fraying in the vacuum tubes.

If you have a buddy in your area with Vag-Com, they can run a diagnostic test. A technician should be able to diagnose this pretty quickly, if what I am thinking is in the right ball park.

In truth, I may be jumping to conclusions ... it gets real hot, and at the 5 year mark dirty, in the engine bay. So, I always first assume I have vacuum tubes frayed or stuck solenoid problem.

Randy brings up a good point as well, may be a bad misfire condition.

Acceler8

thanks guys