MK7 GTI Misfire - Please Help!

[White_7gti]

So i've got a MK7 GTI 2014 (63) plate. The car is constantly misfiring started off as a hot start struggling and has lead up to a complete misfire more or less all the time..

It's been going on for just under a year the car has had everything checked and a lot changed...

150 PSI compression across all cylinders and no vacuum leaks (smoke test done)

New Cam adjuster magnets
New PCV valve
New spark plugs
New HPFP
New o2 sensor (bank 1 sensor 1)

Injectors tested and only one injector on cylinder 4 was faulty and replaced
GDI injectors all rebuilt and tested okay
Carbon/Walnut clean carried out

ECU Tested and okay (latest map flashed)
Coil packs tested and okay
Wiring loom tested and resistance of cabling and was fine

The car is at the point where it drives okay for a short while and now will all of a sudden throw a engine and EPC light you can hear the car is running on fewer cylinders and goes into limp mode. After a minute or 2 will resolve itself and drive fine again for about 10-15 mins

Codes are for cylinder 1 & 4 misfire. Misfire under direct injection.

Can also see that cylinder 1 & 4 are shut off or turned off when the misfire happens. Swapped the shut off valves but still cylinder 1 & 4 that still seem to misfire.

The car has been to 3 reputable garages and even VW but no one can actually find a cause.

I'm at the point of just getting rid of but want to know if there is anything i've missed or worth checking before doing just that.

[White_7gti]

I should add the misfires occur at idle or even under load and the car does struggle to start around 9/10 times. Very occasionally does it start as normal and this always on a cold start never when warm.

[Carbon VW]

Hi there. A year is a long time to be suffering those issues. Can you share some more info on the car. Mileage? Can you share the exact fault codes from a scan ? Is the Intake manifold and associated sensors still original
Is the car tuned ?

[willni]

Well you're at least at the stage where you can rule many of the go to items out.

How's the MAF sensor performing?
Are you running an aftermarket cat or is the original leaking?
Have you had an engine borehole scope carried out to see if any of the valves are bent or sticking?

[Philip]

I'd be tempted to swap the coil packs from cylinders 1 and 4 with 2 and 3 and see if the misfire continues but on the other cylinders. I say this because previously (and not on a GTI) I've had coil packs bench test as OK but which were failing under running conditions.  Given what you've already done it's a small amount of time and effort to rule out what could be a £100.00 fix.

[madstaff]

I'd be tempted to swap the coil packs from cylinders 1 and 4 with 2 and 3 and see if the misfire continues but on the other cylinders. I say this because previously (and not on a GTI) I've had coil packs bench test as OK but which were failing under running conditions.  Given what you've already done it's a small amount of time and effort to rule out what could be a £100.00 fix.

You would hope any reputable garage and VW would have done this, i certainly would have, to see if the fault code/s follow the coil packs.

Easy enough to try, and as you say, its when theyre hot they start to break down.

[White_7gti]

Hi there. A year is a long time to be suffering those issues. Can you share some more info on the car. Mileage? Can you share the exact fault codes from a scan ? Is the Intake manifold and associated sensors still original
Is the car tuned ?

Yes it has been going on for nearly a year and just been from garage to garage. Its completely standard other then a resonator delete. I did have it mapped to a stage 1 but had it reverted about a few weeks before the issues occurred and had done a 1000 odd miles or so before anything happened. It has been re-flashed again with the latest VW ecu file but made no difference.

Fault codes are:
Cylinder 1 misfire
Cylinder 4 misfire
Cylinder 1 misfire under direct injection
Cylinder 4 misfire under direct injection
Multiple cylinder misfire detected.

Intake and sensors are all original other then the pre cat 02 sensor this has been replaced with a genuine VW Part.

MAP sensor has been tested cleaned and retested but no difference and seems to be fine. 

Mileage on the vehicle is 71143 exactly.

[White_7gti]

Well you're at least at the stage where you can rule many of the go to items out.

How's the MAF sensor performing?
Are you running an aftermarket cat or is the original leaking?
Have you had an engine borehole scope carried out to see if any of the valves are bent or sticking?

MAP Sensor has been tested cleaned and retested and performs perfectly.
The car is bog standard other then a res delete. The stock CAT is in place and i'm not 100% sure but i'd gather after the amount of checks been carried out this would have been tested but i will double check it. Nothing leaked when we done a smoke test.
Borescope carried out and everything internally looks okay.

Also had oil changed done and filtered to find hardly any metal/no particles in oil too.

[White_7gti]

I'd be tempted to swap the coil packs from cylinders 1 and 4 with 2 and 3 and see if the misfire continues but on the other cylinders. I say this because previously (and not on a GTI) I've had coil packs bench test as OK but which were failing under running conditions.  Given what you've already done it's a small amount of time and effort to rule out what could be a £100.00 fix.

We have tried this even tried new coil packs to find no difference.

[joe6]

Could it be a fuel pressure problem? Clutching at straws now as all the usual checks and more seem to have been done.