APR stage 2 Golf GTI Surging/Pulsing Issues

**adammk6gti** · 19-01-2017, 07:37 AM

Hey guys,

Late last year I ended up purchasing a 3" de-cat de-res DP (Ebay pipe) for my 2011 MK6 GTI. I had already done Carbonio intake + stage 2 piping on my APR stage 1 tune. So went and got the APR stage 2 flash from eurotune. Instantly made the car feel different, no more massive spike in torque and a more linear response through out the whole rev range.

However, I have noticed a strange surging/pulsing when accelerating in any gear between 2.5k and about 5k revs. Its alot more noticeable in 4th/5th/6th like accelerating hard on the motorway. Its hard to hear but i have a video of it happening below. lts like the car tries to pull hard like it should, then cuts back slightly then pulls hard again and then cuts out. this happens maybe 2 times a second creating like a WUB..WUB..WUB..WUB..WUB.. sort of sound. AS soon as i kit 5k rpm the car pulls like an absolute weapon, smooth and powerful till it revs out.

Here is a video i recorded of it happening, i start to pull in 4th at about the 8 second mark and thats when you hear the wub wub wub.. Its very noticible in real life and when you drive the car it feels off.

I've recently (5000km ago) had a BFI stage 2 clutch go in so its definitely not clutch slip and the revs aren't increasing in the pulse section like a clutch slip would indicate. I'm a little lost for ideas as to what could be causing it. I've searched here and on other forums but failed to find anything that was similar apart from this thread but this was for low (2.5k-3k rpm) Surging/hesitation/pulsing under hard acceleration - VW GTI MKVI Forum / VW Golf R Forum / VW Golf MKVI Forum / VW GTI Forum - Golfmk6.com and were talking about APR tune being a little off.

I've got the car to go in on Monday to eurotune but would love to hear inputs from you guys. Also, If anyone on the Gold Coast has a VAG-COM I'd be more then happy to shout you a case of beers for a bit of help with some logging on the weekend for some data to send to APR.

Cheers,

**Reedy** · 19-01-2017, 07:48 AM

I had something similar and no amount of logging could find the issue. I know it's the wrong thing to do but I started just buying new parts. Came across a cheap MAF genuine so put that in and then the car ran perfect. Try clean it first but that did nothing for me. This issue could be a number of things, diverter valve, boost leak, fuel pump, coils......good luck.

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**adammk6gti** · 19-01-2017, 08:20 AM

Originally Posted by Reedy

I had something similar and no amount of logging could find the issue. I know it's the wrong thing to do but I started just buying new parts. Came across a cheap MAF genuine so put that in and then the car ran perfect. Try clean it first but that did nothing for me. This issue could be a number of things, diverter valve, boost leak, fuel pump, coils......good luck.

hmm ill have a look into the MAF but really hoping its not a replace parts till its gone exercise. I forgot to mention changing back to the stock tune has none of these issues when accelerating hard (grated less power overall).

**Lucas_R** · 19-01-2017, 09:56 AM

The APR "stage 2" intake pipe is known to cause issues as the PCV connection is rubbish and causes leaks. So if you have air leaking from that connection it could be contributing to the car running poorly.

**adammk6gti** · 19-01-2017, 12:33 PM

Originally Posted by Lucas_R

The APR "stage 2" intake pipe is known to cause issues as the PCV connection is rubbish and causes leaks. So if you have air leaking from that connection it could be contributing to the car running poorly.

Thanks lucas, ill have a look around the valve. I have noticed a small amount of residual oil around the connection to the Stage 2 piping coming from my catch can pipe in the past. maybe this connection has gotten progressively worse and now causing air to leak? Ill try popping it off and cleaning it up then re-installing with a fresh hose clamp.

Will runs with a VAG-COM give me some info about the condition of the MAF sensor?

**Reedy** · 19-01-2017, 05:21 PM

Like O2 sensors these just slow down with age, depending the amount of klms on the clock is to whether change them or not. Testing the MAF I have only seen it done with a bolt metre and the findings were inconclusive as it always gives you a reading it's the speed that it does it.

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**adammk6gti** · 19-01-2017, 07:57 PM

Originally Posted by Reedy

Like O2 sensors these just slow down with age, depending the amount of klms on the clock is to whether change them or not. Testing the MAF I have only seen it done with a bolt metre and the findings were inconclusive as it always gives you a reading it's the speed that it does it.

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So I had a little read up on any issues with the Apr intake. Also looked into the stage 2 piping like Lucas said. Noticed that the return line from my oil catch can where it meets the intake pipe had no hose clamp around the carbon section. It was pressed in the well with 2 o-rings but no clamp so could have air pushing through that.

Made me think if the catch can was changed by my mechanic when he did the service. Went and changed it and was proper full of water n gunk. Ripped it out and emptied it well. Plumbed her back up and drove down to get the hose clamp. Feels alot better after the clean but still feel it ever so slightly. I'll post back after I drive tomorrow with and update.

Still would like to look into replacing maf, 90000 on the clock.

**Reedy** · 19-01-2017, 08:03 PM

Pleased you are making progress.

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**adammk6gti** · 20-01-2017, 08:48 AM

So after driving to work this morning I realise the issue is not resolved. Might have been just ambitiously thinking it was gone last night when I headed down for a quick drive to get a hose clamp. Anyone else go inputs if they have experienced this issues before or clues to what may be going on?
Where abouts on this forum should i be posting if I want to see if someone is close by and could lend a hand with some logging (Gold Coast/Brisbane)?

APR stage 2 Golf GTI Surging/Pulsing Issues-ppa3jdm-jpg

*Edit - For reference, here is the connecting to my catch can and the missing hose clamp around the carbon nipple section.

**Lucas_R** · 20-01-2017, 10:44 AM

Originally Posted by adammk6gti

So I had a little read up on any issues with the Apr intake. Also looked into the stage 2 piping like Lucas said. Noticed that the return line from my oil catch can where it meets the intake pipe had no hose clamp around the carbon section. It was pressed in the well with 2 o-rings but no clamp so could have air pushing through that.

I wouldn't put a traditional metal hose clamp on the carbon intake pipe as you will likely crack the carbon fiber. Given you have a catch can connected there and not the OEM PCV hose, the 2x o-rings would/should do a pretty good job of sealing that connection up (providing they are a snug fit). If still leaking, go get yourself some black RTV sealant from Supercheap etc and that will fix it for good.

Now you mention that your mechanic recently serviced the car - did this surging issue exist before the service or did it only appear after the service? I wonder if the engine is starving itself of fuel and this is why its dying off momentarily? The HPFP's on the TSI engine are pretty good but they do fail from time to time. Another thing to check would be the fuel filter - has this been replaced and if so, has the correct unit been used.