Hey all,
I've been experiencing some surging at wot for some time now. My car is a 2007 with 24000 miles, upgraded piston dv, apr hpfp and APR 93 2+ file. I experienced this same issue before the HPFP and also checked the cam follower which is fine. There is no oil around the cap so I ruled out a bad pcv. The plugs were also changed and re-gapped.

Here is a video that I took. Both runs are at wot. As i get into the higher rpm range (about 5000+) in 3rd and 4th gear, you'll see the surge that i'm talking about. It's not just in the gauge because you can feel the surge in acceleration also. Just wondering if anyone has experienced this and has/had a fix. I ran logs and am waiting for APR to get back to me but in the mean time was hoping to see if anyone else had similar issues.

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If I was to hazard a guess, I'd say you have a small vacuum leak somewhere..is the DV still operating correctly..it may have a small split in the diaphragm...probably worth swapping it out for another to check?

Best of luck.

Cheers.

Nick

 

I have the upgraded piston DV already so I don't think that's it. The car was actually doing the same thing with the stock diaphram DV also.

 

It looks like you have a leak somewhere. Do you have any exhaust mods or some sort of manifold upgrade? You can also check your N75 as well.

 

I just changed the N75 last weekend and still the same. I'm gonna do a leak test and cross my fingers and hope that's it. I just don't think that a leak will cause the surging.

 

Would love to hear what you find as I have the exact same problem. However, I'm in a 2000 B5 S4. I have full APR exhaust, downpipes, bipipe, and running Stage 2+ 93 as well. Just had an oil change and the shop usually does a pressure test but didn't mention anything. I find it doubtful that it's a leak since it can hold higher boost in lower gears without a problem. Guess it's time to go back in. Maybe there is a MAF problem.