Mk4 GTI Boost issue

[BI65ND]

Hi guys,

I did a bit of a back trade with a dealer for my Bora 4mo and I now own a mk4 golf gti. Loving the car so far except I have one issue with it that I am trying to fix. When accelerating, and the car comes on boost, if I back off the accelerator the car jerks pretty harshly, almost to the point of a bunny-hop. Anyone got any ideas or encountered this before??

I am certain it has something to do with the turbo setup, ie wastegate, manifold, BOV, boost leak, the turbo itself, etc as it only happens when on boost. I've checked all the piping and everything seems alright - doesnt appear to be any obvious leaks. The car does have a **vomits** monza blow off valve in it that I didnt find till after the trade (sneaky pricks spray painted it black so it just looked stock), but it is plumbed back and seems to be in working order - dont worry, it is going ASAP!

Any ideas? I've thought it may be that the excess pressure is not being released properly because of the **** house BOV, but could it be something else? The car has a 3 month warranty on it, but the dealer is not exactly a VW expert, and I want to know what this is myself before trying to get them to fix it.

[AGO41T]

does it have a Manuel boost tee? coz it does that wen you back off

[Jarred]

go to a mechanic and get the engine mounts checked.

try and find someone else with a standard BOV setup & borrow that to test.

[ntails]

I could be wrong but i seem to have this problem when my spark plugs are at the end of their life.

[BI65ND]

Na no boost tee, not sure on the spark plugs... doesnt feel like a sparking issue. I ordered new ones yesterday anyway because they havent been changed in a while. Had a good mechanic check it out before I got it, and he said everything seems good, will get him to check the mounts though.

[Jmac]

Hi guys,

I did a bit of a back trade with a dealer for my Bora 4mo and I now own a mk4 golf gti. Loving the car so far except I have one issue with it that I am trying to fix. When accelerating, and the car comes on boost, if I back off the accelerator the car jerks pretty harshly, almost to the point of a bunny-hop. Anyone got any ideas or encountered this before??

I am certain it has something to do with the turbo setup, ie wastegate, manifold, BOV, boost leak, the turbo itself, etc as it only happens when on boost. I've checked all the piping and everything seems alright - doesnt appear to be any obvious leaks. The car does have a **vomits** monza blow off valve in it that I didnt find till after the trade (sneaky pricks spray painted it black so it just looked stock), but it is plumbed back and seems to be in working order - dont worry, it is going ASAP!

Any ideas? I've thought it may be that the excess pressure is not being released properly because of the **** house BOV, but could it be something else? The car has a 3 month warranty on it, but the dealer is not exactly a VW expert, and I want to know what this is myself before trying to get them to fix it.

Teah you could have a bit of a pint there, DV could be faulty, or N75 mate that can cause this however only on boost not over run, what i read here is you are on over run, i think that why the guys are jumping at mounts. Just rechecking its on over run off the gas?????
Jmac

[fuzion]

check your vacuum lines first, they all tend to be brittle and break
change your diverter definitely, even stock one i would suggest as those **** things leak something chronic (monza)

cpacks, spark plugs.. scan the car?

[BI65ND]

Thanks for that, Ill be getting one of those APR R1's in a couple of weeks so not gonna bother going back to a stock one in the meantime. Doing a bit of investigation into this n75 valve now. Just doesnt seem normal for a leak to make it so rough, I could understand it would make the car lose heaps of power, but dont really see how a leak could do that to the car.

[Jmac]

Leaks will alter your AF mate , thatll make it rough for sure
Good luck , log it mate and see what everything is doing
Jmac

[VDUB-BUD]

My car was doing that.
Replaced the N75 valve to J type and it did the trick.
Also boost comes on a lot better.

[BI65ND]

Wots better, N75H or N75J?? And wot's the difference with our cars? I read something from UK that the H hits harder but the J is smoother, but their cars are specced differently to ours... would it be the same thing for ours?

[fuzion]

either or will work fine. better off getting a J imo.