'08 GTi FSI K04 Breaking up high RPM under load

[TSMILEY]

I have a good solid 10k on the plugs, so being K04, they are probably due for replacement. However, this issue has been going on since installing the K04, about 10k ago (I don't drive my car very hard to have been concerned about the breaking up in upper RPMs under load, plus a CEL never came on). I installed these plugs at the time of K04 installation. The deposits are light gray, uniform on the porcelain as well as the electrodes.

Now, after adjusting the gap to 0.028, I will tell you I notice quite a nice difference in normal driving, however between yesterday and this morning, I never had a good safe moment to be able to go full throttle to see if that helped with the breaking up. I am also having a hard time finding a road where being able to run logs in third gear to red line would be safe. I might just have to try a 2nd gear pull to see if that might give sufficient data.

I also found my old set of NGK PFR7B spark plugs that I was running when I was Stage 2+. They have less that 5k on them, and are in fantastic shape. I have set the gap on those to 0.028, and just might throw them in this afternoon to see how they react

 

[GIACUser]

Light grey sounds good in terms of how the plugs should present if things are firing correctly. CEL will not come on for all error codes.
2nd gear will not provide good data, 3rd gear so-so, 4th is really where you want to do the logging because it puts the motor / turbo under load.
3rd gear best if you can do it going uphill again to provide as much load as possible.

Plugs indicate good things are happening generally but some logging would tell you whether it is an ignition, fuel or boost issue going on when you put the pedal all the way down.

If you can't find an airport road or somewhere desolate to run a log you can always pay the money and log time on a dyno.

 

[TSMILEY]

Just to update, I have installed my NGK PFR7B spark plugs gapped to 0.028 yesterday. I haven't been able to secure my Ross Tech from work to log yet, however, driving home last night and back to work this morning, I'm thinking I'm going in the right direction here. It definitely feels better. I also tried a 4th gear, uphill pull from 2k RPM to *almost* redline (had to let off due to traffic) and it definitely felt better throughout the rev range. I am still going to get logs as requested, in the near future. Thank you again to everyone for help in this! We have some great minds in this group!

 

[clockwise33]

I've been dealing with this same issue for a few years. I've become resigned to the fact that the APR K04 tune simply isn't compatible with aftermarket intakes. I use a Neuspeed intake and even with consistently good fuel trims (about +/-5%) I have always had breaking up near red line. Spark plugs make a big difference with this. I ran PFR8S8EG gapped to 0.028 for a year with pretty good results, only occasionally having hiccups, especially in clod weather. This Spring the hiccups became more pronounced so I starting experimenting with different plugs and gaps. I tried BKR8EIX at several gaps and found them to be the worst by far. I tried wide electrode (nickel) BKR7E at several gaps and still had hiccups. I tried PFR7B at several gaps and found that 0.022 works well and 99% eliminated the symptoms. We will see what happens when the cold weather returns. I believe the ultimate fix for this issue is moving to a different tune that plays nice with intakes (I've heard good things about GIAC and UM). Case in point, APR updated their MK6R tunes to include the ability to select the option of an aftermarket intake but never updated the FSI K04 tune to do the same, which should tell you something...

 

[BurgerGuy]

Am running Unitronic Stage 2+ with BKR7EIX gapped to .028. Before, I was running BKR8EIX with the same gap and had bad misfires, but also had issues with the S3 injectors I believe as replacing them with OE Golf R injectors (instead of Bosch) resolved my misfire problems. The BKR7EIX plugs just made things smoother.

 

[TSMILEY]

Both of you have very interesting input on this topic. I'm hoping I'm not going to end up needing to get another tune.

 

[BurgerGuy]

Would use plugs the tuner recommends for their tune.

 

[TSMILEY]

I just wanted to update things at this point. So I've been driving the NGK PFR7B plugs for about 3 weeks now. STILL breaking up under load. It seemed better for a while, but really broke up on me last night the one time I really pushed it. I am going to make a point to data log very soon. I need to get to the bottom of this! So frustrating.

 

[MagicMK]

I just wanted to update things at this point. So I've been driving the NGK PFR7B plugs for about 3 weeks now. STILL breaking up under load. It seemed better for a while, but really broke up on me last night the one time I really pushed it. I am going to make a point to data log very soon. I need to get to the bottom of this! So frustrating.

When is the last time you changed your DV, and what revision do you have? I was reading through this thread and am really surprised the car isn't throwing a CEL based on your explanation of the issue. Also, do you have the original VW OE air intake, and if so, have you tried reinstalling it to see if the car has similar issues with the stock air intake? Finally, I didn't notice you mention how many miles were on the car - what's the mileage, and was the MAF *ever* changed?

 

[BurgerGuy]

When is the last time you changed your DV, and what revision do you have? I was reading through this thread and am really surprised the car isn't throwing a CEL based on your explanation of the issue. Also, do you have the original VW OE air intake, and if so, have you tried reinstalling it to see if the car has similar issues with the stock air intake? Finally, I didn't notice you mention how many miles were on the car - what's the mileage, and was the MAF *ever* changed?

Before you throw anymore parts at the car get some logs. It would also be good to see what your fuel trims look like and those can be checked with the car parked as long as you haven't cleared faults or disconnected the battery recently.

When I had misfire problems the only CEL I got was for the actual misfires, nothing else.

The OE airbox isn't a bad idea. Not sure on how the MAF scaling of IE's intake (what OP is using) compares to the OEM unit.

 

[ROH ECHT]

I too feel a look at certain data is good to rule out other possibilities. Such as mass air, fuel pressures, timing advance, etc.. Mine had issues with breaking up without codes just once. That was when I switched from my GIAC tune to DriverMotorsport 8 or 9 years ago. I switched to PFR7B plugs gapped to 0.026" which Bronson suggested and still it broke up in higher revs at full throttle. It would just buck and spit rather than continue to accelerate. This doesn't mean it will be the same issue, but mine didn't even throw any misfire codes. Then I replaced the oem coils with new oem and it was fixed.

Couldn't TSMILEY just unplug the MAF and run it MAP based briefly to see if the MAF reports are indeed affecting it?

 

[MagicMK]

Hello everyone. I said I would keep you posted if I had an update.

Good news! The problem is solved. The culprit was a faulty diverter valve.

I had a type C (stock), so visually we couldn't see if it was broken or not, but after having installed the type D we also flashed the remap back and the problem is solved! Car pulls like a beast now without those annoying hick-ups at low/mid-range RPM.

Next on the list is new spark plugs, air filter (maybe APR intake) and general inspection/service so the car is ready for the winter.

Really glad the problem is solved. This means that apparantly even the 2.0 TSI's (CCZ) can have a faulty diverter valve.

also shoutout to my tuner (info above) who helped me out really nicely!

I found this on another VW forum. The guy threadjacked someone else's thread on a GTI stumbling and this guy had his car tuned. It ended up being the DV in his case, and I know in my personal case, I lost a lot of torque due to a ripped early rev diaphram-style DV. I see in the APR kits that they may not replace the DV, and just add a new mounting flange. I didn't see a new DV mentioned in the OP's list of updates/mods. He appeared to purchase a new RS4 fuel valve (wow are they expensive, btw) and I'm guessing that did not work... but based on another forum post I read, it stated that most of the mods were no longer calling for an upgraded pressure valve and were okay with the OE pressure valve (possibly due to software revisions).

At any rate, I'd recommend reverting back to the stock air intake to remove that possible variable as a problem. Make sure you have a new-er air filter in the stock air intake, as well. Then, has the MAF ever been replaced - if not what is mileage? Finally, has the DV ever been replaced, if so, what revision, and if not, then definitely replace the DV (esp given the extra demands of the mod). Also, I'd recommend you consider buying the DV from FCP Euro if you do decide to change it out... FCP has a no-hassle lifetime warranty on all parts, so given the demands of your modded car, the lifetime warranty could be valuable (plus their prices are already very good irrespective of the warranty).

What do you guys think?

 

[clockwise33]

I just wanted to update things at this point. So I've been driving the NGK PFR7B plugs for about 3 weeks now. STILL breaking up under load. It seemed better for a while, but really broke up on me last night the one time I really pushed it. I am going to make a point to data log very soon. I need to get to the bottom of this! So frustrating.

What gap do you have your PFR7B at? PFR7B at 0.022" is what I'm running right now and it pulls smooth to redline.

 

[TSMILEY]

When is the last time you changed your DV, and what revision do you have? I was reading through this thread and am really surprised the car isn't throwing a CEL based on your explanation of the issue. Also, do you have the original VW OE air intake, and if so, have you tried reinstalling it to see if the car has similar issues with the stock air intake? Finally, I didn't notice you mention how many miles were on the car - what's the mileage, and was the MAF *ever* changed?

@MagicMK, I installed a new D revision diverter valve when I installed the K04 on my car. Unfortunately I do not have the original intake as it was quite broken a long time ago, so when I got my IE intake system, I pitched it in the garbage. My car has about 136k on it, and as far as I know has the original MAF. I've owned the car since about 85k, and I can tell you I personally have never changed it.

Before you throw anymore parts at the car get some logs. It would also be good to see what your fuel trims look like and those can be checked with the car parked as long as you haven't cleared faults or disconnected the battery recently.

When I had misfire problems the only CEL I got was for the actual misfires, nothing else.

The OE airbox isn't a bad idea. Not sure on how the MAF scaling of IE's intake (what OP is using) compares to the OEM unit.

@BurgerGuy, I am going to make a point of getting some logs over the next couple of days.

I did have the battery disconnected this past weekend as I installed a set of 034 Motorsport street density mounts and dogbane insert. I've had them laying around for months. Finally got around to the install.

I wish this thing would throw a CEL when it breaks up!

IE makes a big deal out of their MAF scaling on their intakes which is why I chose this particular unit.

 

[TSMILEY]

I too feel a look at certain data is good to rule out other possibilities. Such as mass air, fuel pressures, timing advance, etc.. Mine had issues with breaking up without codes just once. That was when I switched from my GIAC tune to DriverMotorsport 8 or 9 years ago. I switched to PFR7B plugs gapped to 0.026" which Bronson suggested and still it broke up in higher revs at full throttle. It would just buck and spit rather than continue to accelerate. This doesn't mean it will be the same issue, but mine didn't even throw any misfire codes. Then I replaced the oem coils with new oem and it was fixed.

Couldn't TSMILEY just unplug the MAF and run it MAP based briefly to see if the MAF reports are indeed affecting it?

@ROH ECHT , my OEM red top coils aren't very old. I installed them when I was stage 2+ when one of my original black tops failed. I would hope that the issue wouldn't be from a coil.

What gap do you have your PFR7B at? PFR7B at 0.022" is what I'm running right now and it pulls smooth to redline.

@clockwise33 , Currently they are at 0.028. They *were* at 0.022 and I still had breaking up just like now.

I found this on another VW forum. The guy threadjacked someone else's thread on a GTI stumbling and this guy had his car tuned. It ended up being the DV in his case, and I know in my personal case, I lost a lot of torque due to a ripped early rev diaphram-style DV. I see in the APR kits that they may not replace the DV, and just add a new mounting flange. I didn't see a new DV mentioned in the OP's list of updates/mods. He appeared to purchase a new RS4 fuel valve (wow are they expensive, btw) and I'm guessing that did not work... but based on another forum post I read, it stated that most of the mods were no longer calling for an upgraded pressure valve and were okay with the OE pressure valve (possibly due to software revisions).

At any rate, I'd recommend reverting back to the stock air intake to remove that possible variable as a problem. Make sure you have a new-er air filter in the stock air intake, as well. Then, has the MAF ever been replaced - if not what is mileage? Finally, has the DV ever been replaced, if so, what revision, and if not, then definitely replace the DV (esp given the extra demands of the mod). Also, I'd recommend you consider buying the DV from FCP Euro if you do decide to change it out... FCP has a no-hassle lifetime warranty on all parts, so given the demands of your modded car, the lifetime warranty could be valuable (plus their prices are already very good irrespective of the warranty).

What do you guys think?

@MagicMK , I am running a not very old rev. D DV. Also, while I have recently purchased the RS4 fuel valve, I have not installed it at this point. No, the MAF has never been replaced that I am aware of since I have owned the car.

I do have a new FORGE DV kit that I haven't gotten around to install yet. But, we'll see where things start to point when I get some logs!