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Discussion Starter #1
I have a MKIV GTI 1.8T that I'm having issues with surge/misfire.
Problem has been there for a while now but is getting worse.
It's not a constant problem it comes and goes. No codes what so ever.
At steady rpm it seems to miss fire and when coming to a stop sometimes it feels like it wants to die. When on freeway I hit the gas and it stays at 5 psi like in limp mode.
I let off and hit again and get full boost. I have a front mount with cold air intake, forge diverter valve, 3" down pipe and APR ecu I normally run 91 octane program. Have not yet replaced N75 valve (it's original). I was going to replace it with an Audi 034H valve. Any ideas on what my problem is?? PLEASE HELP!!!
 

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Only code that ever comes up is my cat failure (not running cat).
I have the same issue on my 1.8t
It's old already and have learned to accept that nothing is meant to last.
I did the spark plugs and it runs a bit better. I also noticed today the exhaust manifold gasket needs replacement.
 

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Discussion Starter #7
I have the same issue on my 1.8t
It's old already and have learned to accept that nothing is meant to last.
I did the spark plugs and it runs a bit better. I also noticed today the exhaust manifold gasket needs replacement.
I've done all the basics and no improvement. The boost is real sloppy. Peaks and drops a lot. I'll be ordering a new n75 valve Friday so we will see how that works.
 

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I've done all the basics and no improvement. The boost is real sloppy. Peaks and drops a lot. I'll be ordering a new n75 valve Friday so we will see how that works.
N75 is probably your best bet, but it may not help. These cars have a mind of their own.
 

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Discussion Starter #11
There would be little or no boost.
I've also noticed if I hit the gas fast it doesn't boost as smooth as getting in it slow.
I never have a problem with not boosting just is sloppy.
It holds boost fine just no power somtimes.
 

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I've also noticed if I hit the gas fast it doesn't boost as smooth as getting in it slow.
I never have a problem with not boosting just is sloppy.
It holds boost fine just no power somtimes.
Change your plugs recently? Regapped them?
 

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Prolly a noobish question , but how do you gap the spark plugs ? I read they have be gapped specifically when you go stage 1 and I'll be going stage 1 pretty soon
A gapping tool/feeler gauge

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Prolly a noobish question , but how do you gap the spark plugs ? I read they have be gapped specifically when you go stage 1 and I'll be going stage 1 pretty soon
Unless I'm mistaken, factory gap is .032. I've read that as you get more aggressive with tuning you want to be closer to .028. I'm at .030 with Stage 2 and I have no misfires or problems.
 

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Yessir. About 5k ago. New coil packs from recal.
Then I'd stick to n75 replacement and go from there.

In the meantime you could try cleaning both the map and maf sensors.
 

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What's a good cleaner?
I buy the AutoZone brand stuff, to be honest. Just make sure you give the sensors proper time to dry before reinstalling and starting the car.
 
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