Getting fed up with this poor running now :-(

[bigtrev200]

For months now my 2001 VRS hasn't been running quite right and I've gradually worked my way through the usual repairs of:

- Throttle body clean

- New coil packs via recall

- New MAF

- New breather pipes

- Full service

The problem is that on 0-10% and 50-100% throttle the car runs perfectly - it's smooth, boosts fine and generally feels spot on. However, if I use between 10-50% throttle I have a problem as the boost builds up. As I'm going through the gears the boost starts to build up nicely but then at about 2500rpm, just as the torque is reaching its maximum, I get this kind of boost cut - it's the only way I can describe it. This is also really noticeable on the motorway in fifth gear. If I'm sat at 70mph and want to accelerate up to 80-ish and I use between 10-50% throttle the car just doesn't pull smoothly at all, and can actually get really jerky sometimes. Strangely over the last few days I've also noticed a nasty burning smell when this happens that seems to last for a few seconds.

I thought my problems were solved last week when I fitted a new Compbrake DV, and it definitely cured a lot of the problem. However, over the last few days the boost cut off has gone back to exactly as it was before and I'm really losing patience with a car I know can be soooooo good. Any suggestions people? Any help would be really appreciated.

[chicken_eyebrow]

Have you got VCDS or know of anyone near you thats got it (what part of Kent are you from) that can do some logging and find out what it's actually doing?

It sounds like whatever the fault is it's not bad enough to throw a fault code and engine management light and the buy-and-replace approach hasn't worked so I guess the next step is to try and really narrow it down.

Is yours standard or remapped? A lot of these ones that have hesitancy issues, when owners have exhausted all other options, it turns out to be the map thats the problem.

[sjh1986]

You could try an N249 bypass. I have some of the above symptoms, and I've bypassed mine to see if it was the N249 valve that was playing up, and I seem to have cured some of the issues mine has. It's dead easy to do and you don't have to physically remove lots of things from the engine. The valve can basically control the dump valve via the ecu if necessary, and when it fails can open it whenever it likes, resulting in hesitations etc...

http://www.briskoda.net/forums/topic/189811-just-done-the-n249-bypass/page__p__2267854__hl__n249%20bypass__fromsearch__1#entry2267854

Have you also considered looking at the N75 valve? The little black pastic unit with three pipes going to it next to the DV. This controls the wastegate and also causes funny business should it have a fault.

[VRS Mike]

You could try an N249 bypass. I have some of the above symptoms, and I've bypassed mine to see if it was the N249 valve that was playing up, and I seem to have cured some of the issues mine has. It's dead easy to do and you don't have to physically remove lots of things from the engine. The valve can basically control the dump valve via the ecu if necessary, and when it fails can open it whenever it likes, resulting in hesitations etc...

http://www.briskoda...._1#entry2267854

Have you also considered looking at the N75 valve? The little black pastic unit with three pipes going to it next to the DV. This controls the wastegate and also causes funny business should it have a fault.

Defo worth doing the above.

[sjh1986]

Defo worth doing the above.

Mike,

Have you completely removed your N249? I've bypassed mine and will probably remove it all at some point, along with the SAI. I'm heading off to R-Tech next month hopefully for a Stage 1, so It would make sense to remove it all I guess so that they can map fault codes out?

Sorry to the OP for hijacking the thread lol.

Sam

[bigtrev200]

Thanks for the advice guys - I hadn't thought about bypassing the N249 before and shall defo give it a go. Do you know what size piping I need to get and where I can get it from? Car spares places are a bit shocking around my way so I tend to get most things online now.

With regards to the N75 valve I've got a mate who's just bought an Audi TT 180, and I'm assuming that his N75 will be the same as mine (do you know if I'm right?). I might do a quick swap at sometime to see if there's any difference in the running of my motor.

When I first bought the car back in July I got it scanned and it brought up the 16684, 16686, 17705 and 17545 error codes. I'm not sure if my car is remapped or not unfortunately. It's got a Jabbasport induction kit and goes much quicker than I thought a stock VRS ever would (I've easily pulled a few car lengths on another VRS in an unofficial traffic light tear up) but I've got no paperwork to back things up. I'm wondering if I contacted Jabbasport and gave them my reg number they could tell me if they have given the car a little power magic in the past??

[sjh1986]

You need 4mm I.D piping if I remember correctly. I got mine off ebay for about 4.37495p lol

I believe the TT 180 should have the same N75, so it's worth a shot to see if it makes your car drive better. Somebody may correct me of course!

My mate has a mapped vRS, and his will easily pull away from mine 2nd and 3rd, so it's possible yours has been remapped. Either that or the other one you raced was poo.

Edited 16 March, 2012 by sjh1986

[VRS Mike]

Mike,

Have you completely removed your N249? I've bypassed mine and will probably remove it all at some point, along with the SAI. I'm heading off to R-Tech next month hopefully for a Stage 1, so It would make sense to remove it all I guess so that they can map fault codes out?

Sorry to the OP for hijacking the thread lol.

Sam

I think it's still connected to stop any codes but my whole vac system has been stripped out and simplified. A well known member on here did it for me. You can't go wrong with R Tech mate, Nic is the daddy on 1.8t tuning.

[Bowders1]

Hi there the kind of symptons you state which sound like boost spiking that the ECU is trying to restrict the boost and go to a kind of safty mode which is probably why you get the jerkyness.

This type issue is typcally harder to get to the bottom of without getting the ECU cell codes rechecked and or a rolling road run to tease out actual running conditions.

Sounds like you have done the most common actions you listed.

additional possibities could be:

- Faulty N75 valve(yes the TT180 and golf variants of the 1.8t are the same, P/N is 058 906 283 F)

- Faulty Throttle body(where throttle position is not being found)

- Faulty or weak Turbo actuator(not allowing boost to hold firm)

- poor air leak in breather pipes and ECU holding back to safe mode

Persomally I would not do the N249 remove until you find out what is wrong.

Removing or deleting parts when the car is not running well could cause further issues.

Most folks remove the N249 , SAI, N112 either for Engine bay clean up or when they already know one of those items are at fault. This is IMO anyway

My suggestion is get the car checked by VAGCOM and a tuner to do a run in the car at full load.

[chicken_eyebrow]

Jabba might be able to tell you if they remapped it if you give them the reg... or just contact the previous owner(s). Strictly speaking if it's remapped your insurance need to know, but if you don't know yourself then I doubt the insurance could hold that against you in a claim.

If you drive your mates TT 180 that should be a fair comparison - if the Octy is a lot quicker then I'd suspect it's been remapped.

There is apparently a known hesitancy in the standard map which can be magnified by a remap:

http://www.briskoda.net/forums/topic/227848-boost-question/page__fromsearch__1

[bigtrev200]

Right, I did the VCDS thing at my local garage this afternoon and it didn't bring up a single fault code, which I thought was pretty annoying and I couldn't then pinpoint a problem. However, one of the mechanics at the garage said straight away that it would be a faulty air mass sensor as he had seen the same problem on a Seat Leon Cupra and that bought back no fault codes.

As a test I unplugged the sensor (that I bought six months ago on eBay), took it for a run up the road and the car ran perfectly! I suppose this points to a faulty sensor so I'll be buying a pukka Bosch one ASAP.

[chicken_eyebrow]

Yep, best to fork out and buy the proper stuff

[Raf_]

Yup that's the problem m8, if the car is running better with it unplugged its at fault