how to test the coilpack harness on 1.8t a4?

[graham_f]

anybody have some kind of test for the coilpack harness?
the car is a 04 1.8t avant quattro with 220k. eurodyne 1+ program with the tt injectors.

I have a randomly reoccurring misfire on cylinder #2 that i cant seem to shake.
I replaced the plugs and then re-gaped them.no change.
coilpack 2 died so i replaced them all. no change, so i swapped them around...Still no change.
its always #2

It only mostly just happens on a cold start but today it showed up while driving.
I have the CEL for the misfire but nothing else... vcds code 16686 i think. I clear the code but it comes back in a day or two.

any other ideas? The internet is a scary place that says my head is cracked... i'd prefer to do test or two before jumping to that conclusion.

thanks,
Graham

[PRY4SNO]

Re: how to test the coilpack harness on 1.8t a4?

knock sensors?

[Natty54]

Re: how to test the coilpack harness on 1.8t a4?

How is the condition of #2 connector and harness?

[graham_f]

Re: how to test the coilpack harness on 1.8t a4?

if it was knock sensors wouldn't i get some kind of fault?

visually the harness looks good, no cracking, kinked or broken wires at all. Looks pretty much like new.

[onceover]

Re: how to test the coilpack harness on 1.8t a4?

Pull the plugs and shine a flashlight down into the cylinder. If cyl2 is a clean silver color and the rest are black you can start worrying about coolant getting in.

[100%VAGitarian]

Re: how to test the coilpack harness on 1.8t a4?

fuel injector.

[graham_f]

Re: how to test the coilpack harness on 1.8t a4?

i took a look this afternoon. I couldn't find any faults in the harness other than the #1 harness plug has a broken locking tab. Still pushes in all the way... just doesn't click in the locked position. always stays plugged in solid like the others.
the plugs all look good, other than maybe it running a little rich, but my o2 sensor is really old and i have kinda poor mileage...so i have a new one on order anyway to hopefully take care of that.
all cylinders look nice and dirty... so that's a good thing right?

can i test the injectors at home or do you need special equipment for that?

[Disturbo]

Re: how to test the coilpack harness on 1.8t a4?

A bad 02 will cause the car to missfire and get poor mileage. Swap the injector from cyl 2 to 3 and see what happens

[clover168]

Re: how to test the coilpack harness on 1.8t a4?

Most likely bad fuel injectors.

Sent from my SGH-I317M using Tapatalk

[graham_f]

Re: how to test the coilpack harness on 1.8t a4?

How is the condition of #2 connector and harness?

after trying many things, i finally gave in and cut away the nice coilpack harness rubber. I was hoping to avoid this before having some real evidence that its the issue.
Everything looked good but once i opened it up i found many bare wires with cracked insulation all over the place.
I peeled the insulation back until the wires looked new and clean, replaced a section of the crappy wires and insulated and taped the harness back up.

Now my regular driving is back to normal. no misfires, pulls nice and smooth.

But my start up misfire hasn't changed at all... if anything its lasting a little longer when the car is first fired up.
the cel flashes but goes away after the misfire(about 25 sec. long) stops.

once this has happened the car runs and drives like new, until the car is parked for a few hours. Then its back.
any ideas?

Edit: i should add that the flashing cel is not being recorded and when i scan with vcds no faults are found.

[onceover]

Re: how to test the coilpack harness on 1.8t a4?

Hate to say it but thats what my car was doing when the head was cracked. Coolant would get into the cylinder after letting the car sit for a while and would then burn off after restarting

[100%VAGitarian]

Re: how to test the coilpack harness on 1.8t a4?

how many more people need to post fuel injectors before you bother to look at those? seems much easier than assuming you have a cracked cyl head on a normally good running engine. with no loss of coolant. just saying.

[Lars]

Re: how to test the coilpack harness on 1.8t a4?

I'm gonna say bad injector also.. Probably leaking down when car is sitting and after running it pressurize's and holds a charge of fuel in it while running.

[hooddub]

Re: how to test the coilpack harness on 1.8t a4?

how many more people need to post fuel injectors before you bother to look at those? seems much easier than assuming you have a cracked cyl head on a normally good running engine. with no loss of coolant. just saying.

To be fair he did solve half the problem but I would agree with the leaky injector. Good place to check anyways.

[graham_f]

Re: how to test the coilpack harness on 1.8t a4?

how many more people need to post fuel injectors before you bother to look at those? seems much easier than assuming you have a cracked cyl head on a normally good running engine. with no loss of coolant. just saying.

im sorry, you'll have to forgive me for not doing as you say right away.


ive been going through and taking care of the known issues i have and reading about the things i don't understand. Since i don't have an injector flow/leak tester sitting in my garage and i dont have a spare set of injectors, i thought i should try a few things before moving into unknown territory.

and to be clear, i never assumed my cyl head was cracked...it was just another post i found while researching. The comment was actually quite similar to yours.

anyways, thanks for the help