So the other day I installed a N75J valve and it ran good for a night, started pulling really nice until today when I ran the car. The car is sputtering once any significant boost builds, and one time sputtered so badly it flashed my check engine light.. and the car does go into limp mode for a few seconds.

I thought after doing research on the forums that it was the plugs, changed them out today with correctly gapped new plugs, not fixed.

I forgot to mention I changed the valve back to the stock valve before the new plugs.

I checked on vag com for codes and it had some like "missfire" and "MAF frequency too high" and "MAF frequency too low"

I cleared them and nothing helped. When I cleared the codes with vag com, does that reset the ecu to relearn? If not, how do I do it?

The ECU might be the problem, or it could be coils? Any help would be great.. I just got my car back and I am NOT going back to driving a mini van!!

 

When you clear codes, you do just that, clear the codes. Next time you have a misfire the codes will return.

You say not plugs or coil packs, you mentioned you changed and regapped the plugs, but what about the coil packs?

Another potential source of misfire is if your coilpack harness is damaged. Inspect the wiring harness and look for exposed wires. The insulation on the harness is often damaged by long term heat exposure.

 

if its coils you would probably notice the misfiring more at idle..
got a clean air filter?

 

Yeah I have a clean filter and I will check the wiring today. So how do I reset the ECU? Do I disconnect the battery for a few mins?

And no, I havent checked the coil packs. I dont have any extras laying around to try. If it was a coil woldnt vag com say that only one cylinder is misfiring? I need to check the codes again today and post them up here...

 

3 Faults Found:
17608 - Boost Pressure Control Valve (N249): Mechanical Malfunction
P1200 - 35-10 - - - Intermittent
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 - -
16685 - Cylinder 1 Misfire Detected
P0301 - 35-00 - -

HELP PLEASE!!!

 

Ok, so I tried the stock DV to make sure it wasnt my aftermarket DV causing the issure. NOT THE PROBLEM!

So far I have tried new plugs, and new DV... could it be the coils?? If it was wouldnt it be acting up at idle too??

Please help! I am kinda stuck and have a free day today to go get parts if I need to.

 

Could definitely be the coils. I bought some brand new ones off ebay, and they went bad within a month. Had similar reaction and codes that you are seeing. I thought, "no way it could be the coils" but I put in the old coils and it ran fine.

You said you changed the plugs? What part number did you use? Are you boosting above stock? The heat range plays just as big a part as the gap on the plugs. If you are modified make sure you got the proper plugs for that and not the stock ones. The information is in the FAQ if you need to look up what plug number to get.

 

I am boosting over stock but nothing has changed from when the car was running perfect until now... so the plugs are not the issue. So when you had a bad coil, you couldnt notice anything wrong at idle, but when you actually put any real boost into the engine the thing would missfire? Cuz thats exactly whats happening to me.

 

i say coils or then MAF

 

It WAS a coil. I replaced it and everything is running great! Thank you all for your help... gotta love VAG COM!

My car is now officially stage II!