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Misfiring at high speed - Stage 2

crypto

crypto

Crypto-Designs.com
Location
fort myers florida
Car(s)
2008 MkV GTI
Every since i installed my downpipe and went from stage 1 to Stage 2 I've had an odd issue.

Around 6k rpm in 3rd gear, hitting about 80mph I start getting random misfires. When I shift into 4th they stop for a second but as soon as the RPM's pick up again the misfiring comes back but a lot worse. This is pretty much the case for 5th and 6th too. The car just misfires and won't go any faster, if i keep my foot down it'll creep up to 100mph but that's it.
This only happens in Stage 2 mode, when i put it to stock there's no problem.

I thought this was just fuel cuts but after talking with APR they don't think it is. Arin suggested it may be my O2 sensor.
I checked for codes at autozone but there are zero. The plugs are NGK's and only have about 10K miles on them.

I'm gonna try to find someone local to do logs, but until then does anyone have any ideas to what's wrong with my car?
 
xSabretoothx

xSabretoothx

Fast w/ training wheels
Location
Raleigh, NC
Car(s)
2008 GTI
Is this just under WOT or all the time during acceleration?
 
sloMk5

sloMk5

___________
Location
Tampa
Car(s)
2007 GTI
Could be your intake. I would misfire/break up in high gears running a K&N intake with APR software. I ended up making a custom one with the tubing and a OE MAF housing, worked very well. You could throw the stock one on to rule it out.
 
07Noside

07Noside

Banned
Location
x
I think slo hit the nail on the head. It can't be an o2 sensor if it only happens in chipped mode and not stock. I'd really like to know what tech at apr said that lol. Moneys on the intake especially because slo had the same intake and experienced the same problem. Slap back on the stocker and see what happens.
 
sloMk5

sloMk5

___________
Location
Tampa
Car(s)
2007 GTI
Because you're flowing more air. I didn't have any problems until stage 2+.
 
crypto

crypto

Crypto-Designs.com
Location
fort myers florida
Car(s)
2008 MkV GTI
sloMk5 said:
Because you're flowing more air. I didn't have any problems until stage 2+.
Click to expand...

so what would be your recommendation? Throw a stock intake on, or just get a different aftermarket intake?

Arin@APR said:
Yes, it absolutely can and even if it couldn't the conversation I had with the OP never included any discussion of stock mode operation. Your asinine commentes are also completely unnecessary.
Click to expand...

sorry for not mentioning the stock mode thing in our conversation. My bad
 
sloMk5

sloMk5

___________
Location
Tampa
Car(s)
2007 GTI
I'd try and borrow someone's stock intake and see if that is the issue before you spend any money.

I was getting multiple random misfires and misfires on all cylinders, usually in 4th and 5th gear. I had new coils already, so I replaced my plugs with no luck, and eventually tried the stock intake and it went away. It was choking my topend pretty badly, so I decided to do a custom tubular intake with the stock housing and it worked great.

Also FWIW, I talked to K&N about it, and they basically told me tough shit, we only design intakes to be compatible with stock cars. I can't tell you this is or isn't your issue, but it's definitely a good place to start. Good luck.
 
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