aby feels limp / not boosting maybe?

[Chris_w]

hi guys, after a bit of help.

Whilst doing a 100 mileish run yesterday, my car seems to have lost a fair bit of power.

Before, when you put your foot flat down, there was a breif pause, then the car would surge forward quickly. Now it just seems to gradually accelerate.
It doesnt seem as bad as what ive been reading on here about limp mode and boost cutoff, but it definitely isnt right, the car idles fine, and still runs smoothly, and theres no flat spots as such.

The car recently had a homefry remap, and this was its first long run since having that done. It ewas fine on the drive down (100 miles), then after being left for two days, when i came to start it up, there was a fair bit of smoke for a second, which immediately cleared and it hasnt smoked since. It pulled well on the way home until after i switched it off at a service station. Ever since i restarted it, its been a bit of a wet fish.
The car has an aftermarket, think its bailey iirc, dump valve fitted, could i be loosing boost through this now that the turbo is boosting that bit higher?

Any suggestions, i dont know where to start! Get a boost gauge maybe to see whats going on?

Anyone got vag-com in oxford area?

Any help appreciated! Thanks.

[dest]

A boost gauge is a definite good investment to keep an eye out for anything abnormal.
I would say its pretty certain to be a boost leak of some sort.
Probably a good idea to get a 710N diverter valve instead of the Bailey one too

[Acidburn]

agree with dest the bailey one's have been known to leak unfortunately as i'd have liked a bailey vent to air one if they made it.

[UrS4boy]

Chris: Here is some info about the by-pass valve including how it works and PNs for the 710N (the infor is for an AAN in an UrS4 but it is basically the same for an ABY)

http://forums.audiworld.com/showthread.php?p=18872998

On a related note, if you are not familiar with the ABY set up, you should browse through the hyperlinks below this AAN engine bay device map. Most of the devices are the same as the ABY except for physical location, e.g. intake air sensor is still near the ABY throttlebody but the throttle body is up near the firewall/bulkhead.

http://forums.audiworld.com/showthread.php?p=18945405

[S2central.net]

Dreaded air leak of some sort I suggest... Often provoked by new found boost levels after an ECU upgrade if you have tired old hoses... Or maybe just a loose clip somewhere.

A boost gauge is your friend though - no way to tell if its on target boost levels or not. RESET the ECU and try again. Pull any fault codes from it first though. Annoyingly, most boost leaks don't show up on the ECU.

[Rusty]

Does the car re-start? There are occasions where a lost sensor still allows the engine to run as normal, only with mechanical boost over rather than WGFV controlled, I know that the crank and cam hall senders can cause this but the car will no re-start.

Get the Bailey valve out and replace with a new OE DV, it'll be fine for a bit and removes that from the equation.

Best thing would be to pop along to MRC in Banbury for a full health check including boost leak test and VAG comming.

[newsh]

I'm thinking WGFV.

Or hose come loose at the ECU.

[Chris_w]

Cheers for all the advice guys, great stuff and very helpful!

Im going to look into what everyone has said on the matter today and tomorow and see what i can come up with, and report back with my findings.

I take it a new DV and WGFV (701N and N75 yeah?) are genuine parts only, google doesnt seem to be brining up much results.

[Rusty]

Yeah, genuine parts. DV should be about £25 and WGFV about £50. Look at the TPS thread on here to get the best deal

[Chris_w]

replaced wgfv and dv, and its got worse!

on the plus side, it does feel smoother at low revs with the new parts.

The rev counter seems to be sticking sometimes, could this be connected?

[newsh]

Fuses all checked? Fuse 24 and then from there check the wiring for continuity to the WGFV.

[newsh]

http://www.s2forum.com/forum/showthread.php?t=35188&highlight=wgfv+fuse&page=3

[Chris_w]

fuse 24 is fine. Havent had a chance to trace the wiring to the wgfv.

Im resetting the ecu, then driving 250 miles in it this afternoon, which should hopefully kick up some error codes and try and get it vag-com'd next week.

[Chris_w]

right, so i reset the ecu, was boosting a fair bit better, but not smoothly, could feel the car surging then backing off on steady 3/4 throttle.
pulled a lot better when accelerating in top gear to pulll past people on the motorway.
however, after stopping at exeter for chips and drinks, it was back to it old self.

this coincided with the rev counter sticking again. The rev counter didnt srtick when it was feeling better.

going to try and source a boost auge tommorow and get i vag commed asap now that i am permanewntly in cornwall and have time and space to work on the car.