Bad mapping? ED30 random misfire

[Jackged30]

Hi guys just after some tips after doing some work already to try and resolve it,
Had codes relating to timing, maf and vvt solenoid, replaced these and done a new belt and chain kit with the vvt adjuster. Engines runs beautifully, unlike previously no misfires on idle or normal driving. If you stay between 3.5 - 4 it misses and checks up a flashing Eml light, if you keep the revs higher it doesn’t miss, pulls fine all powers still there. Is it mapping? Any way I can check before I shed money out to get the map changed? (Bought the car with this problems)

Car also has a Decat down pipe

I take cam is at -1, valves aren’t restricted, injectors flowing fine, no vacuum leaks ect

[GVK]

Flashing EML means catalyst damaging misfire, if you have VCDS you can see which cyls are misfiring group 14 iirc

It's usually injectors on these tbh.

Mapping, very doubtful.

[Jackged30]

Flashing EML means catalyst damaging misfire, if you have VCDS you can see which cyls are misfiring group 14 iirc

It's usually injectors on these tbh.

Mapping, very doubtful.

I might be stupid but why would it be telling me about cat damaging misfires with a decat? Forgive me if I’m being thick 🤣 I personally would consider injectors being f*cked but then why is it fine once I’m past that rev range? And it’s missing 1 - 4 not a bad miss or loads of misses but 1 miss too many lol. Logged it on a 10 mile drive and Mis count was 6 - 10 per cylinder

[GVK]

You didn't say it had a decat.

 

[Jackged30]

You didn't say it had a decat.

 

Missed that part out mate apologies, any other reason it would flash with a decat?

[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]

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.

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.

[Jackged30]

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?

Not a clue who mapped it, bought it blind as a “fixer upper” seller had said it hasn’t been mapped which is a load of as it goes like stink. It’s got standard internals and a new cam follower. I think I’m going to get the injectors out and have them tested and clean the valves while mani is off, other than not sure where to go next, logging fuel pressure it actual always meets requested other than peak boost rpm, literally for a split second drops and goes back up very odd to me

[pudding]

Ah OK, you 100% need HPFP internals mate if it's mapped. I recommend VIS stage 1 as it uses the standard spring. The stupid money APR and LOBA ones use a crazy spring that eats through cam followers in no time.

It's hard to tell sometimes with the actual and requested fuel rail pressure as you only need to back off the gas slightly and the requested pressure drops like a brick.

What you want to see is a hard pull in 4th from 2500 - 6000 rpm (hard to do on the road, I appreciate) and the requested and actual matching each other. A few bar difference is nothing to worry about.

You can also check the requested boost pressure to see how far it's been mapped.  Stock GTI is about 1 bar. If it's like 1.3 bar or higher, definitely mapped. If you have VCDS, the boost readings will be in millibar, so standard pressure will be 2000 millibar because the MAP sensor can't read below atmospheric pressure, so you deduct 1000mbar, and that's your boost pressure.  If you see 2300-2500mbar, it's running 1.3-1.5 bar boost.

I wouldn't waste your time with cleaned/checked injectors, they just wear out. Put new ones in. Refurbed ones work OK for a while, but don't last.

[Jackged30]

Ah OK, you 100% need HPFP internals mate if it's mapped. I recommend VIS stage 1 as it uses the standard spring. The stupid money APR and LOBA ones use a crazy spring that eats through cam followers in no time.

It's hard to tell sometimes with the actual and requested fuel rail pressure as you only need to back off the gas slightly and the requested pressure drops like a brick.

What you want to see is a hard pull in 4th from 2500 - 6000 rpm (hard to do on the road, I appreciate) and the requested and actual matching each other. A few bar difference is nothing to worry about.

You can also check the requested boost pressure to see how far it's been mapped.  Stock GTI is about 1 bar. If it's like 1.3 bar or higher, definitely mapped. If you have VCDS, the boost readings will be in millibar, so standard pressure will be 2000 millibar because the MAP sensor can't read below atmospheric pressure, so you deduct 1000mbar, and that's your boost pressure.  If you see 2300-2500mbar, it's running 1.3-1.5 bar boost.

I wouldn't waste your time with cleaned/checked injectors, they just wear out. Put new ones in. Refurbed ones work OK for a while, but don't last.

okay mate, I’ll get some more logging done and have a look for some hpfp internals thank you for the advice mush!