Power Dips @ 3000 RPM on S4???

I'm going to take a stab that 3000rpm is near max boost pressure so that it's probably something to do with something giving under high boost pressure, and combined with the drop from 20 to 17 psi that would seem to all point in the same direction.

I would probably do the DV's first, but bolloxs to paying big bucks for the forge one's just to prove a point, go down to your Dealer and pick up a couple of 710N's and give them a try.

If these aren't the problem then next place to look at is the actuator system, as on chipped cars it can be that the boost pushes the wastgate off of it's seat and simply adjusting it will help. I doubt it's the actuator solenoid as these tend to put the car into limp mode when they go wrong and give an error code.

The above's just a pointer, but hope it helps /ubbthreads/images/graemlins/beerchug.gif

When was the car chipped?

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Grantos said:
Hi Guys,

I'm having some grief with an S4 at the moment, the car has been REVO'd and is standard other than that. At around 3000rpm i'm getting a bit of a kick back, not sure what the problem is. I'm going to replace the ricirc valves with forge ones. I've had it down Mosley's garage and when he performed a live data stream read on it, it hits 20psi and intermittently drops to 17. He suggested soft or sticking actuators. Has anyone ever had this problem or can shed some light on it? I dont want to play with the actuators if theres only a possibility that its them, engine out is expensive!!

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I assume your REVO software is for 95RON fuel. If so it is likely to have similar characteristics to the APR software. I have 2 chipped modes, and the APR 95RON mode overboosts until 3000rpm then drops off exactly as you describe. In my case it's not a fault with the car, as changing into the 98RON map or OEM map cures the issue.

Can you revert to OEM map, and try to replicate the same issue.

Other things to check though, Throttle body boot, F pipe, intercooler hoses and DVs - all a weak point on modified S4s, all cause boost leaks if left to neglect.