03 Audi A4 1.8T P0302 (Only Cylinder 2 Misfire) | Have tried everything to fix this

[meadam09]

Hello. I have used Audizine to help fix a majority of my car repairs but I thought I would post a thread because I cannot figure out what is going on. So I recently, a little over a year ago purchased a 2003 Audi A4 1.8T Quattro Wagon and I have been rebuilding it (literally and I am exhausted). So I have pretty much-done everything to the car so far

-Battery
-Turbo
-Intake manifold
-power steering hose (leaking)
-driver and passenger window regulators
-hatch hydraulics
-ignition coils (like 4 sets)
-spark plugs (like 4 sets)
-transmission fluid and filter
-heater core flush
-wiring harness (for ignition coils and fuel injectors)
-serpentine belt
-fuel pump & filter
-alternator
-radiator
-fuel injectors (all 4)
-o2 sensor (not sure which one.. I think it was the one connected to circuit 1.. not quite sure)
-value gasket
-cleaned MAF sensor
-replaced all temp sensors (green and grey)
-coolant refill tank
-fixed all air leaks (car was running lean but not anymore)

So after doing all of these repairs, I am still having a code P0302 which is saying that the only cylinder that is misfiring now is #2. The system isn't running lean or anything else. I tried doing research and it said that this cylinder is the first in the firing order? Maybe that explains why my car sometimes stalls at a cold start and runs like crap until I give it some gas. Does anyone have advice? What this could be? I am about to give up..

[BumblebVR6]

I’m having similar issues. Going to do a compression check this weekend. Bought mine with over 200k miles and the head has been replaced before. You never know though. Could be cracked head or issues with rings. If you’ve replaced coil harness and injector harness and done process of elimination with coils and injectors, I’d start there.


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[meadam09]

How do you do a compression check? Should I try to do it on my own or ask my mechanic..

[egovreau]

How do you do a compression check? Should I try to do it on my own or ask my mechanic..

I think you can rent a compression gauge from AutoZone or any parts places who has a tool loan program.

Compression checks are pretty easy...just remove all four spark plugs, thread the gauge into the first cylinder then turn it over a few times, then check. Repeat for each cylinder. Make sure you pull the fuse for the fuel pump so you're not filling the cylinders with fuel.

However, a compression check will only tell you there's a problem (or none) but not specifically where. A leak down test will do a better job of pinpointing the what.

There's plenty of information out there on the B6 Coscast AMB head...the common thread being they have a higher than normal tendency to crack at #2 cylinder. If you're getting a flashing CEL on a cold start, that indicates a misfire. Most likely from coolant that has leached into the cylinder as the engine cools from it's previous run. Before you start the car before the next cold start, remove #2 plug and shine a light into the cylinder. If it looks wet, it's going to be either oil or coolant (do you notice a gradual drop in either?), Which indicates a cracked head or blown head gasket.

Either way you'll need to remove the head.

If the head is cracked, then you'll want to replace it with any small port head with the Audi/VW logo and the work GERMANY stamped on the side. Heck, I would just replace the head anyway, while it's off the car.

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[meadam09]

Wow, thank you. Based on everything I have done thus far, do you think this is what it could be?

[egovreau]

I think it's a good chance, but I would still play out the scenario and troubleshoot the problem without needlessly throwing parts at it.

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[old guy]

Perform a block gas test. I had a cracked head and was able to confirm with this test. It's a very simple test to perform. Kits are relatively inexpensive. Clicky click®