Quote Originally Posted by EvolutionArmory View Post
He’s talking about a leak down test of the cylinder head. Was the one you bought used? Leak down test will tell you if your valves are sealing.

Verify the head is good and then go after the injectors as a potential cause.

Have VCDS monitoring misfires when when it’s acting up. Block 015 and 016. If it’s only misfiring on one cylinder, then you’ll know which to target. If Leakdown is bad on that cylinder, you’ll know it’s the head. If not, it’s probably an injector.

Then pull that plug and see if it smells like fuel or is wet. If it’s wet, your injector is leaking.

Another thing I would do is do an intake runner motor adaptation in basic settings and see if it passes. It might be failing but not throwing a code. Doing its basic settings test might force it to fail and throw a code for it. Or it will pass and you’ll know the tumble flap system is working right and you can cross it off the list.
So the head is used but I had it checked over with penetrant to look for cracks and stuff and the car was never overheated just had a valve issue which had to pull the head for. Compression is ~200 on all cylinders, and after a couple seconds usually runs great. So I checked fuel pressure on the rail yesterday and at idle it sits at 750 psi and after 60 secs of turning the car off it lost 90 psi. I let it sit overnight and it was at 100 psi this morning. The car didn’t stumble though this morning like it has before. Anyways, I’m assuming this is pointing to either a leaking injector because I don’t smell fuel anywhere. I’ll pull the plugs and see what I find. Thank you.