Surging 9n3 GTi Under wot

[h100vw]

sammbb, a question about DVs. The Forge, Turbosmart, etc are all piston style, the APR is a diaphragm. I've forgotten but what is the original, is that diaphragm as well? It's been a long time since I changed mine, I've forgotten a lot about the negatives of the piston type until I read your reply

Std is diaphragm too.

[sambb]

Don't get me wrong, piston types arent bad, not at all. They have the more bullet proof design of the two when it comes to lasting under more severe conditions. They still need to be maintained though to prevent piston stiction in the bore and to keep the base seal clean. Some designs just rely on perfect machined mating surfaces to seal ie no o-ring on the piston base so it wouldn't take much crud to give you a drama. The stock diaphram one will do everything the piston design does (and more - see the vacuum stuff above) andmore or less maintenance free, right up until the point that the diaphram tears. I haven't compared APR ones to stock diaphram ones - I actually was going to get one 'till I saw the price.

[Stuwey]

I ran an APR one for 7 years without issue - can't fault that!

[DeanB]

thanks for the reply

I've had my APR R1 DV coming up to 7 years like Stuwey ... problem free so far

[noone]

Nup there isn't anything wrong with them. Do you think porsche would have stuck these things on 911's if they were as utterly crap as people say. They might have longevity problems but just replace one when its shredded. They hardly cost anything. They actually have two big advantages over after market piston style DV's too.

I'm not sure what different versions Porsche use, but I'm talking only about the N75 controlled diaphragm diverter on the 1.8T. I have the electronic controlled diverter on my 2.0T S3, which is totally different and has a piston revision to the original diaphragm which had some minor issues. The main issue with the stock diverter was how it wore over time with the higher boost pressure (double and tripple stock boost).

I never had issues with my stock diverter, I upgraded early on. If someone has boost issues, it is definitely something to try, even borrowing one for a spin around the block to see if it makes a difference. I had no issues with the Forge 007, but still upgraded to the 008 which I preferred, I cant comment on the different types, brands and styles. I bypassed all the VAC and N249 system as well, seemed to work best with CC, but never did back to back testing, just how it felt at the time.

[FLOSPOLOGTI]

hi guys. still surging...noticed more (albeit only due to being only gear really able to test within open road speed limits) when fully or almost fully flooring accelerator say from 3000rpm mark and expecting it to pull cleanly post initial full boost comes on. Boost comes on great (APR V2, GFB dv and N75J) - no boost gauge - i.e. initially pulls great, but then as speed builds, starts fluctuating the rate of acceleration. If you didn't know better, you'd think I was deliberately slightly backing off on the accelerator, back on, then off etc. For those who have experienced this - what was the fix??

[Blue9N3]

Mine does the same. Has stopped doing it recently. Don't know why. Maybe hot weather?


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[seangti]

Do you have access to VCDS to scan for faults and log the car? I'm typing this from a phone so can't see your location, put a shout out here or in the VCDS section of the forum for assistance, or go see the APR distributor if they will to check over it.

Do a full scan of the ECU then log it. By logging boost (actual and requested), MAF, AFR (actual and requested), should give some indication as to what's going on. I assume you haven't been fiddling with any other tune/ECU related software to adjust timing or anything.

[sambb]

there was a whole thread on this somewhere in the search facility. It was something about different versions of APR being more prone to it than others or something along those lines. I can't remember if the thread ever came to a conclusion on anything but it might give you a few ideas on things or people to call?

[seangti]

Could be that vvt is activated on WOT on the version 2 tune, that would give the effect you've described. I have no idea if APR have done that on their tunes though, an other than asking APR, don't know how you'd validate.