stumbling issues while boosting

[randy954]

I recently chipped my ecu with apr. I was told the chip gives you smooth power through the rpms but its been anything but smooth. When driving normal with about half throttle the boost seems fine but when i go WOT it stumbles from about 3k to redline. Its like it pulls hard then stumbles real quick then is pulls hard agian then stumbles etc all the way to redline. I dont have any boost leaks that i know of and it holds boost fine. I also changed the plugs to oem bosch platinums before chipping and it was smooth. Was there different plugs i shouldve used or maybe gapped them differently now that im running more boost? Is there anything i should do or check or is that just how apr's tune is?

[randy954]

Anyone?

[enzoB5]

get new plugs, NGK bkr7e if you can find them, but the NGK iridiums/coppers and gap them at .24!! you SHOULD be fine after that.

[Volk14]

Anyone?

What year is your car? I have the feeling that you posted in the wrong forum, if so, post your question in the right forum and you'll get more answers.

[99vwpassataeb]

Sounds like a missfire..and i believe this is in the wrong forum

[Steve in Chicago]

double post

[Steve in Chicago]

I'm on board with the "wrong forum" guess, too. (profile says 2002 1.8t)

Try closing the spark gap like enzoB5 suggested.

Is everything else stock other than the tune? Stock diverter valve?
Is it misfiring or surging?

[randy954]

Ya i just noticed it's in the wrong section.. Mods could you please move it..
But the plugs are new and no it doesn't misfire. I've ran the car and boosted it while it was hooked up to my snap-on verus and it's not showing any misfire at all while doing live data streams and after reviewing the freeze frames everything looks pretty normal. Btw the plugs I used were the bosch fr7 kpp 33's.

[Steve in Chicago]

...but when I go WOT, it stumbles from about 3k to red line. It's like it pulls hard then stumbles real quick then is pulls hard again then stumbles etc all the way to redline. I dont have any boost leaks that i know of and it holds boost fine.

What is the boost gauge indicating while it's doing this? Stock diverter valve or upgraded?
Are there any hardware upgrades your tune calls for that you have not done?
Are there any hardware upgrades you've done that the tune does not call for?

I also changed the plugs to oem bosch platinums before chipping and it was smooth. Was there different plugs i shouldve used or maybe gapped them differently now that im running more boost? Is there anything i should do or check or is that just how APR's tune is?

Have you tried closing the gaps a bit to see if it helps?
No, the tune should be smoother.
Have you talked to your tuner about what the car is doing?

[UrbanLegend]

I recently chipped my ecu with apr. I was told the chip gives you smooth power through the rpms but its been anything but smooth. When driving normal with about half throttle the boost seems fine but when i go WOT it stumbles from about 3k to redline. Its like it pulls hard then stumbles real quick then is pulls hard agian then stumbles etc all the way to redline. I dont have any boost leaks that i know of and it holds boost fine. I also changed the plugs to oem bosch platinums before chipping and it was smooth. Was there different plugs i shouldve used or maybe gapped them differently now that im running more boost? Is there anything i should do or check or is that just how apr's tune is?

I had the same problem when I chipped (also APR). It felt to me like an engine breathing problem and I could see where the coweling over the intake snorkel, with it's fake cutouts, could be getting pulled inward and cutting airflow to the intake under full boost when the turbo is sucking air like crazy. Everyone on here told me I was wrong and that there was enough clearance around it, but after dremeling out the grillwork in the plastic the problem was solved and the engine pulled stronger than ever. Some Passats apparently come with this piece already opened up and some don't. Not sure why.

[randy954]

No when i chipped it the guys over at 034 motorsports said i didnt need to upgrade anything if i was just using the stage 1 tune. I do plan on upgrading the DV and getting a hiflow cat but other than that thats pretty much it. Also i dont have a boost gauge hooked up to see what im boosting. I do have a boost gauge but wheres the easiest place to hook it up at?

[randy954]

Also i did dremel some holes in the bottom of the intake box on the under side of the filter. I did 6 1 inch holes and it just made the car bog in the lower rpms. I covered up 3 of them and the bogging went away but it still uas some flat spots in the upper rpms which imnpuzzled why its doing that.

[Steve in Chicago]

I do have a boost gauge but wheres the easiest place to hook it up at?

"T" it into the short vacuum line that runs from the back corner of the intake manifold to the fuel pressure regulator. Do some searches on the topic. I know I've explained it several times (with pictures) and so have many others.