yagovoz

My car is a 2001 A6 2.8L. It started to intermittently idle rough on startup and display P0300 and sometimes P0302 and P0304. (random misfire, and cyl. 2, and 4 misfire) This happened once or twice a couple months ago. Now the problem is not intermittent, but constant. The car is hardly drivable. I was sure the wiring harness at the coil pack was the problem since someone had put dielectric grease all over it and insulation was cracked, exposing wire. I ordered and carefully spliced in a used harness in good condition. There was no change at all in my symptoms. Flashing CEL, and the 3 codes mentioned above. One time only I had a code P0352 (ignition coil (B) cyl. 2 Prim/Sec. Circ Malfunction. The Coil-pack and ignition wires were replaced 40k miles ago with OEM Bremi and look pretty new. Plugs also get changed pretty regulary.
Any guidance on how to go about isolating the problem? I have an electrical meter and VCDS available.

jseklund

I would swap coil packs 2 & 3 and then test. If the codes come back on the same cylinders, I would then swap coil pack 4&5 and then retest. My bet is you have one coil pack that has gone bad and it is throwing two cylinders off. If you move a coil pack and it moves to the new cylinder, you have your culprit. I am saying you should move one at a time and retest because you will find that maybe only one is bad this way....if you move them both, you may make it more difficult to diagnose.

My next step would be to swap the ignition coils and see if that makes any difference, but that may be difficult if they are both failing on the same cylinder in their bank...

yagovoz

okay, thanks for the suggestion, but I need a little more clarification.

My car has this:

rather than individual coil packs. How and where would I switch coils?

I might add, too, that 5 wires connect to this coil pack unit. Power, ground, and 3 wires that send the spark signals. Wire one services cylinders 1, 6. Wire two services cylinders 2, 4 and wire three services cylinders 3, 5. Might this make more sense as to why cylinders 2 and 4 are both misfiring? Could I have a bad internal connection or short in the coil pack unit? How could I prove it?

jseklund

Scratch everything I said. Sorry about that - your car has a totally different setup. My guess is the coil pack module has to be replaced, although I don't know if 40K is normal or not for those to go as I have no experience with that setup.

Either the coil pack is toast or those two wires are toast, my bet is on the pack itself...not sure how to test it in this case.

yagovoz

Unfortunately my ignition coil pack was bad after just 20 months and 32k miles. It was a new BREMI coil pack when installed, and has no extended warranty offered by BREMI. (wires and plugs were all new OEM too) The way these things go bad, I have to break with my usual philosophy that you get what you pay for and its worth spending the extra money on OEM. $125 for Bremi and $58 for Richporter Technology, who offers a 1-year warranty. At that cost I could replace this thing every year and still come out ahead lol.

There is no good way to swap coils with this setup, short of cutting the harness wires, re-splicing them AND changing the position of the ignition wires, while being VERY careful not to change the engine timing or firing sequence.

But, one useful test is to remove your fuel pump fuse, remove the ignition coil pack harness, and use a 12v LED tester to check for a signal with one lead on the brown wire and the other on the small signal wires, checking each one-by-one as someone keeps the key turned as though cranking the engine. If the Engine computer is sending a signal you will see the tester flash briefly about 2 times a second for each wire. This eliminates any problem with the electrical signal, i.e. from a cam position sensor issue.

SloopJohnB@mac.com

Replace your ignition coil with either a meyle or bremi coil from FCP Euro.
Lifetime warranty.