Ok, here's what was just done: 2000 Coupe A4 3.42's 2800 stall
Patriot Stage II LS6 Heads
Comp Cam: 224/228
LS6 Intake
28# injectors
Kooks LT Headers
Kooks 3" Exhaust

I went to an out of state shop for a dyno tune. All was going well through the 4th dyno run. Numbers were a little lower than expected...but other than that, it sounded great. 377.86 rwhp and 358.54 max torque

Then while adjusting the timing to accept my 150 NX wet shot, the car had some "popping sounds". Like there was a miss or timing was off. Please understand, I don't know enough about the engine to get real technical. The first opinion was that one of the knock sensors went bad. When starting at idle and in 4th gear at a slow acceleration, the car seemed to bog down...like a fuel issue or timing problem. When the knock sensors were turned off, the car ran smooth...until at WOT. Then there was still a "miss" popping sound. The Tech showed no air/fuel issues, the timing seemed to be pulling from somewhere, but no codes were thrown and there was no detonation shown. Check engine light did not come on either. They were puzzled. I'm going to have the technician post on here as well to help further explain this strange problem.
Bottom line. The car has the knock sensors currently turned off. It runs very well from idle up until WOT. At WOT there is a loss of power with what appears to be a miss that may or may not be due to timing being pulled out.
Three suggestions were: 1) Crank position sensor has gone bad. 2) Cam position sensor has gone bad 3) The reluctor wheel turned during the last dyno run.

I am open to any suggestions right now. Until this is resolved, I am without nitrous or WOT. Please help.

BTW, on the way home, I opened it up a few times, I noticed NO miss sound and the car acted like a beast (or at least to me) two of the times. The other times, there was noticible popping (like popcorn) and some power loss.

Other things to keep in mind: Car mileage 28k , stock plug wires, V plugs, air fuel ratio on best tune was almost flat at 13, we never got off a nitrous dyno run.

I am anxious to get this car running, so any help would be greatly appreciated.

 

Thinking outside the box perhaps.....rev limiter?

 

Not the rev limiter. It still happens while under redline.

 

What's your AFR at WOT on the street??? If it was consistently 13 on dyno it will be leaner on the street. Could be lean up top and popping in which case - keep your foot out of it. My .02 :D


[Modified by Bink, 12:13 AM 5/19/2004]

 

If it were a miss I would say you could have a broken valve spring.

Did you already have your heads inspected to make sure the valve seats were alright?

Judging by your numbers I would say there is a problem. With those mods I would think there would be more power in it.

It is very possible you have a dropping seat/valve, or they are just not sealing.

If worse comes to worse, do a leak down test.

One more thing, it could be valve float, loose rocker arm, improper pushrod length, etc. Normally a car will bog down up top (and show on the dyno graph) with valve float.....usually a weak spring could cause this.




[Modified by z0sense, 11:29 PM 5/18/2004]