Hi, looking for some help with a misfire on an A4 b7 2.0tfsi BUL engine code.

The engine idles rough when cold, but smoothes out onces it's warm. Seems to run fine when driving.

Pulled some codes:
P0300 - Random cylinder misfires
P0301 - cylinder 1 misfire

Swapped coils (1&4) and the P0301 stayed ar cylinder 1
Swapped spark plugs (1&4) code stayed a cylinder 1

Live data showed the misfire count climbing on cylinder 1. Seemed to count 1 misfire on cylinder 3, but only 1. I'll try and grab more data tomorrow.

Did a compression test on a cold engine, as it seems to misfire worse when cold. Don't shoot me down, I'll be doing another compression test tomorrow on a warm engine to compare:
C1 = 192 psi
C2 = 192 psi
C3 = 194 psi
C4 = 197 psi

I haven't really tested the PSV yet, only blow through the hose from the inlet manifold to the PSV. Blow ino the PSV, no air could pass the valve so I assume its ok?

Not really sure where to go next with this so please pass on any suggestions. Thanks.

If you have access to live data, can you see fuel flow on injectors? Any compression blow-by on injectors you can feel? If you remove injectors, then you’ll need new copper washers, o rings and new torque down bolts. Injector recess needs to be spotless.

Cylinder compression seems fine in terms of tolerances within each other.

Wiring look fine, no chaffing you can see, near heat shield or otherwise.

Hi, so I've been looking though the live data and can only see values for fuel rail pressures. I was hoping to do a power balance to check how the rpm/engine reacts when each cylinder is shut off, but I don't think it's a possible test option on this engine ...?

I can't feel any compression blow-by on injectors and have had a good look around the wiring, but cannot see any damage.

The intake manifold looks in good condition and can't see any leaks on it or any hoses including PCV hoses.

Could it be the PCV?

Although, I'm convincing myself it's the injector.

Looking at the misfire counts, they are much worse when cold. The engine shakes a fair bit too. Then when it gets up to temp, the misfires slow and the engine runs much better.

Edited January 26Jan 26 by Koggy

My understanding of damaged PCV valve is excessive oil consumption and rough idle, although you say yours improves once warm.

This video any use?

 

Regards injectors, you could pull them and get a flow test done, plus get them ultrasonically cleaned. Mark them as they are coded to the car.

There’s a few videos on YouTube regards VCDS and injector values. Carbon build up on injectors would cause a bad idle.

Correct, it improves but doesnt cure it. 

Thanks for linking the video.

I've been looking over the enigine/pipe work/wiring again I've just noticed a leak on the PCV round cap. I can hear it hissing on idle and when I flex it a little, the noise gets louder and quieter depending which way it's moved. 

I assume this isn't normal? Would be great if anyone could confirm.