All Things Mk5 > How to Guides / Troubleshooting
Spark plug gaps
r5gtt:
That's good to know your cars running well now for whatever reason it is. Shane you don't know why it's messing around and misfiring at other times. :thinking:
AJP:
--- Quote from: r5gtt on August 25, 2016, 02:32:58 pm ---That's good to know your cars running well now for whatever reason it is. Shane you don't know why it's messing around and misfiring at other times. :thinking:
--- End quote ---
Yeah I'm half hoping it plays up before or while it's plugged in tomorrow so we can at least get some idea of what's failing. Otherwise it's just a waiting game.
r5gtt:
Pain in the butt fault finding for sure. :thinking: misfiring is usually easy to detect although with these bloody tfsi engines it can be a mystery as you're experiencing.
pudding:
Keep checking for a persistent misfire in the fault codes. Injector 3 went on mine. Naturally no amount of plugs and coils thrown at it solved the problem!
I caught mine early though and was just a hiccup going into boost, not a full on stutter like yours does/did. I replaced all 4 as I'm not going in there again!
It misfired at idle (intermittently) too, but it was a proper and continuous misfire, not a general lumpiness that these engines can sometimes have.
When it started misfiring at 2,500rpm, could you drive through it? Or did pushing the pedal more not increase acceleration, or slow it down? Just asking as I've seen that happen from a blocked cat before. Can't remember what exhaust you've got on yours!
I could drive through the stutter on mine, so the injector was kind of working better with a higher duty cycle. Just had a dead zone.
Keep digging, I'm sure the cause is there somewhere!
AJP:
--- Quote from: Pudding on August 25, 2016, 04:54:08 pm ---Keep checking for a persistent misfire in the fault codes. Injector 3 went on mine. Naturally no amount of plugs and coils thrown at it solved the problem!
I caught mine early though and was just a hiccup going into boost, not a full on stutter like yours does/did. I replaced all 4 as I'm not going in there again!
It misfired at idle (intermittently) too, but it was a proper and continuous misfire, not a general lumpiness that these engines can sometimes have.
When it started misfiring at 2,500rpm, could you drive through it? Or did pushing the pedal more not increase acceleration, or slow it down? Just asking as I've seen that happen from a blocked cat before. Can't remember what exhaust you've got on yours!
I could drive through the stutter on mine, so the injector was kind of working better with a higher duty cycle. Just had a dead zone.
Keep digging, I'm sure the cause is there somewhere!
--- End quote ---
If I tried to drive through the misfire it'd just get worse, so I never attempted it and just backed off. The severity of it correlated with throttle - the more I dipped my toe in the heavier the misfires and the car slowed. It was a flurry of misfires (accompanied by 'pop pop pop' like a DSG burp) rather than one hiccup.
The exhaust is a full Powervalve with sport cat, new earlier this year. I did worry that the misfires wouldn't be doing the cat many favours!
I did have a misfire on idle a few weeks ago, this was fixed by replacing injector 4. There were no problems under load at this point.
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