# Misfires when idling



## classexa (Oct 28, 2019)

Hi there

The car is running just fine when driving but misfires pretty heavily when idling. It's on all cylinders but mostly on Cyl. 3. No fault codes. Coil packs and spark plugs are new. Chain is recently replaced. Are these engines(twin charger, BMY) known for anything regarding this? Carbon build-up on the valves or injectors? Fuel related? I've not replaced the fuel filter yet

Sorry if posted before


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## dejettatdi (Apr 3, 2008)

I’ve had good success with Lucas fuel injector cleaner. It’s like a tuneup in a bottle, it can’t hurt.


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## classexa (Oct 28, 2019)

Indeed, it doesn't hurt. We have STP Injector Cleaner at work. I'll try a bottle of this

Do I fill it up with gas before or after I use the bottle?


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## Leirk (Oct 1, 2020)

Your engine is known for cracking piston ring lands. Do a compression test. Good luck 🍀


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## dejettatdi (Apr 3, 2008)

classexa said:


> Indeed, it doesn't hurt. We have STP Injector Cleaner at work. I'll try a bottle of this
> 
> Do I fill it up with gas before or after I use the bottle?


Whatever the instructions say. Lucas says you can do either. I put it in after filling the tank. 
My 2019 1.4 is running very smoothly and powerful after I added to the tank this last refill. I’ve had other successful treatments with my VW’s. I never remember to add it regularly.


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## classexa (Oct 28, 2019)

Leirk said:


> Your engine is known for cracking piston ring lands. Do a compression test. Good luck 🍀


Sounds promising  I shall do this aswell


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## classexa (Oct 28, 2019)

Added some Redline SI-1 to a full tank. Also replaced the airbox which was cracked and glued back together with some adhesive. Also replaced the charcoal canister tube which was broken but patched up with some adhesive aswell. The oil stick was broken so it didn't seat all the way down. Replaced that one too. The misfires improved a bit but still there.


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## Leirk (Oct 1, 2020)

classexa said:


> Added some Redline SI-1 to a full tank. Also replaced the airbox which was cracked and glued back together with some adhesive. Also replaced the charcoal canister tube which was broken but patched up with some adhesive aswell. The oil stick was broken so it didn't seat all the way down. Replaced that one too. The misfires improved a bit but still there.


Did you check compression? Hate to think you replaced all that stuff on an engine on its last leg! Good luck 🍀


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## classexa (Oct 28, 2019)

That's next on my list. Had to wrench a bit on my Audi in between. Gonna check it this weekend. I'll report back


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## classexa (Oct 28, 2019)

The compression was: 165, 165, 163, 170. Dry(cold) test. So I would say that's not the issue


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