All Things Mk5 > Mk5 General Area
Bad mapping? ED30 random misfire
GVK:
Same reasons as with a decat in my opinion.
I know it's a faff getting the intake off to get the injectors out but that would be my next step.
Northern_ED30:
Flashing EML pointed to injectors on my ED30.
pudding:
Bad injectors are the number 1 cause for hot misfires.
Excessive carbon build up and/or swirl flap deletes are the number 1 cause of cold/warm up misfires.
Bad coils, spark plugs and poor cylinder compression are the reasons if none of the above.
Mapping is always the least likely culprit, but is always blamed first.
Boost/high rpm misfires is usually down to insufficient fuel flow assuming everything else is sound.
And at the bottom of the in-tray of possibilities, we have bad crank sensors (rare), bad cam sensors (they can get covered in swarf), bad VVT (busted oil control ring), timing off spec and bad knock sensors.
Jackged30:
--- Quote from: Pudding on June 30, 2023, 09:41:46 pm ---Bad injectors are the number 1 cause for hot misfires.
Excessive carbon build up and/or swirl flap deletes are the number 1 cause of cold/warm up misfires.
Bad coils, spark plugs and poor cylinder compression are the reasons if none of the above.
Mapping is always the least likely culprit, but is always blamed first.
Boost/high rpm misfires is usually down to insufficient fuel flow assuming everything else is sound.
And at the bottom of the in-tray of possibilities, we have bad crank sensors (rare), bad cam sensors (they can get covered in swarf), bad VVT (busted oil control ring), timing off spec and bad knock sensors.
--- End quote ---
Hi mate, all sensors appear to be working correctly, tiling is all in and new parts. I’ve since developed a cold start misfire/terrible idle but I’m sure that’s down to a vacuum leak somewhere which I will be addressing.
I’m not a mechanic by any means tend to just research and try, if you could guide me with injectors a bit as logically I’d imagine injectors are either working or not? Not an intermittent problem or are we saying they can clog up and decrease fuel flow? Occasionally get what feels like a boost cut at peak boost and rail pressure drops from 90 odd request to 70 actual for a split second but intankcand hpfp are new to be on working order, new cam follower ect
pudding:
Ah you have a decat, I missed that on the first read through.
If the remap didn't include coding out the post-cat O2 sensors, that can and usually does throw the EML against a 'catalyst efficiency' fault. The engine ECU compares the O2 sensor readings in the downpipe to the O2 sensors behind the secondary cat (which you no longer have) and if they disagree with each other, you get an instant EML, which is why they need to coded out. It's just a simple on/off setting in the base map.
Do you know who remapped it? If you do, might be worth asking if they did that. It's standard on most Stage 2 maps, but tuners like Revo leave the standard O2 maps in place on Stage 1, so if it's stage 1 and the cats are binned off, it will EML.
Excessive carbon build up will cause cold misfires, as will swirl flap deletes.....although some tuners have a specific map to correct that. Do you know if yours has had a swirl flap delete?
As for injectors, they only misfire at idle and low rpm when they start to fail, but as yours is missing at 3.5-4K, it could be fuel flow that's the problem as that is the peak boost rpm, which demands the most amount of fuel. Has your HPFP got uprated internals in it? Seems like you've got some fuel short falls. At that rpm and full throttle, you should be seeing 109.9 bar on a standard map, 115-120 bar on Stage 1, and 125-130 bar on Stage 2.
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