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Intermittent Misfire

loccusst

FIA GT Champion
Location
IA
Car(s)
MKV GTI
So here's the tale. I will every once in a while have the cel pop up and it's due to an intermittent misfire with cylinder 4. The coil packs were replaced at around 50k miles thanks to the TSB from VW. I swapped coil pack for #4 and #1 around but the issue is still there. I replaced the spark plugs at about 60k miles. The car has 71k miles on it and the issue has been going on at first start up for the day and never at any other time. This is also an issue that happens at the most frequent once a week maybe. Going to replace the spark plugs again and see if that is the issue I guess.
 

NJdubber

Performance Enthusiast
Location
Northern NJ
Car(s)
Audi A3 2.0T FSI
excessive carbon build-up, bad injector ?
 

09Gitty

Ready to race!
I would bet injector based on replacing everything already. What's your gap at on the plugs?
 

loccusst

FIA GT Champion
Location
IA
Car(s)
MKV GTI
The gap was ok straight out of the box. Maybe i'll try some fuel cleaner. God I will shit if an injector is going bad.
 

skyle

New member
From all of the pics I gave seen cylinder 4 typically get the most valve gunk I would try a bg induction service or if that's too salty seafoam it

Sent from my DROID RAZR using Tapatalk 2
 

loccusst

FIA GT Champion
Location
IA
Car(s)
MKV GTI
I put seafoam in the gas tank so I will see what that does first. Hopefully it will clean the injectors. Just changed the oil so I would like to wait to seafoam the engine itself. The 2.0T is such a dirty motor I just don't know what VW was thinking.
 

TheTroyness

I changed a tire once...
Location
Arkansas
How's the misfire? What do you mean Seafoam the engine itself? Introduce Seafoam via vacuum line? I had the EXACT same problem you describe and tried all the things you tried (Techron instead of Seafoam though). I ended up doing a valve clean and replaced the #4 injector all in one go. I did a write up about it here. It fixed my problem. I don't know if it was the injector or the dirty valves, but as was mentioned already, the #4 valve tends to be the gnarliest.

Sent from my Galaxy Nexus using Tapatalk 2
 
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