misfiring problem

[cmontboober]

whats up everyone, my avh jetta started having misfiring problems. here are the codes:

2 Faults Found:
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 - -
16686 - Cylinder 2 Misfire Detected
P0302 - 35-00 - -

about two weeks ago i was getting codes for all of them misfiring and replaced the coilpack. and this morning pulled the codes for #2 misfiring. I just came in from changing the spark plug and still having misfiring codes. I tested the resistance in the #2 wire and it was slightly lower than the wire next to it so its not the wire, and apparently not the plug either... unless they all have to be the same plugs. also, i changed the fuel filter about 2 months ago.

any ideas?

thanks

[cmontboober]

To update, I swapped the #1 and #2 wires to be sure and I'm still getting misfiring on #2 cylinder. I also swapped the old coilpack in, cleared the codes and still getting the same code. Im led to believe its a clogged injector, can i seafoam it or should i put some injector cleaner in the tank?

[roadsterred]

Putting injector cleaner in the tank can't hurt and the problem may clear up. However, if you have a fuel pressure gauge, hook it up to your fuel injection manifold and take a fuel pressure reading with the engine running. With the engine running, you should have a minimum reading of 36 psi. Also, with the engine running, disconnect the vacuum line to the fuel pressure regulator and the reading should rise to 44 psi.

[Anony00GT]

What kind of coil, plugs, and wires did you install? Swapping back in a known bad coil pack isn't exactly a sound diagnosis.

Compression test next.

[cmontboober]

Putting injector cleaner in the tank can't hurt and the problem may clear up. However, if you have a fuel pressure gauge, hook it up to your fuel injection manifold and take a fuel pressure reading with the engine running. With the engine running, you should have a minimum reading of 36 psi. Also, with the engine running, disconnect the vacuum line to the fuel pressure regulator and the reading should rise to 44 psi.

Ok, I'll try it this weekend... have to get a hold of a fuel pressure gauge. but it seems like the main pressure (upstream from injectors) would only tell if the fuel pump is failing. would it be indicative of a bad/clogged injector(s)?

What kind of coil, plugs, and wires did you install? Swapping back in a known bad coil pack isn't exactly a sound diagnosis.

Compression test next.

-This is the style of the ignition coil... http://www.ecstuning.com/Volkswagen-...h/Coil/ES2325/

-I only replaced the plug on #2 to determine if that was the problem, would've solved the misfire immediately if it was caused by a bad plug. I replaced it with a double platinum plug according to the recommended ngk# on ecstuning for the car.

-wires have not been replaced, just switched to different plugs and corresponding plug on the coilpack to see if the misfire moved to a different cylinder, would've determined if it was a bad wire.

-old coilpack was swapped in because if the same problem persists with both coilpacks then the original one may not be bad after all. It was a method to rule out a bad coilpack.

[ps2375]

Have you done a compression test? If you pull the plug wire and let it run for a bit, then pull the spark plug, is the plug fowled with fuel?

[cmontboober]

Have you done a compression test? If you pull the plug wire and let it run for a bit, then pull the spark plug, is the plug fowled with fuel?

Don't have a compression tester unfortunately.

That's a good idea, what you're saying would show whether or not the injector is working. How would the plug look if it was fouled with fuel?

[cmontboober]

Yesterday I got into working on this car again... pulled all the plugs and wires. the ignition IS working correctly.

I pulled 2 wires at a time and ran the car with a new plug in the wire and they are all sparking. rules out the coilpack, wires, and plugs.

One thing that should be noted is that #1 and #2 have a lot of oil on the plug tip inside the cylinder. I'm going to try to get a compression tester today and i have a feeling this is a sign of a bad head gasket or head problems.

[Anony00GT]

Get a proper spark tester as well. Testing with a spark plug confirms the presence of spark, but you cannot verify spark strength that way. The tester you want is either a HEI tester, or one with an adjustable gap. The little capsules with a light bulb in them are useless.