Hokie07

Hi All,

My A4 is misfiring when under load as I'm running the APR Stage 1 93 program. When I put back into stock mode, I cannot get it to misfire. It doesn't misfire enough to throw a CEL (it's usually only one or two in a row). I hooked up the Ross-Tech software and it looks like it's primarliy cylinder 3 that is misfiring (when I tested it cylinder 3 misfired 14 times and cylinder 1 misfired once). I had the dealer change spark plugs about 8,000 miles ago - do you think I should switch out the coils to see if that's the problem?

_Stormin_

Coils could be the issue, but you should see that problem under stock programming as well...

If you're competent and comfortable enough to change the coils (sounds like you are), it wouldn't hurt to test the theory.

If APR is easy enough for you to contact, you may want to reach out to them to see if they have some known issues with the program and need to adjust anything.

Moviela

A bad coil pack or sparkplug would misfire more than once or 14 times. Prior to switching coil packs, I would move the sparkplugs. Be very careful about disconnecting the primary connector on the coil pack. Cooking on top of the engine the plastic retainer tang becomes quite brittle and is easy to break. Without the retainer micromotions caused by heat and vibration will cause fretting of the terminals and a poor connection that is very intermittant. Examine the coil pack carefully with a magnifying glass. Any crack, defect in the epoxy, carbon track, or corroded terminals makes it a candidate for disposal.

A treatment with Techron might help with any carbon build up, or a bit of debris in the fuel injector causing low fuel charge. Try changing filling stations. So many fast buck artists running stations will bribe the tanker driver to drop 89 octane in the 93 tank. So many "old country" habits die hard.

Then I would inspect the condition of the secondary circuit of the coil packs. The metal tube and internal parts of the high voltage section need to be cleaner than the silverware in your kitchen. The deep recess where the plug lives also needs to be clean, and the exterior of the plug itself. Even fingerprints can harbor arc paths to ground. Remove any dirt, oil, or gasket sealant with alcohol. Shine a bright light down the hole to make sure it is clean. The smallest amount of dielectric grease on the plug terminal will make it easier to install the coil pack.

Hokie07

Thanks guys, I will check it out. I might start with my APR dealer because they recently reflashed my ECU after the Audi dealer updated my ECU following part 1 of the oil consumption test. I checked for faults again and I am now getting this:

1 Fault Found:

4629 - ECM Power Relay Load Circuit: (J271)
P068A 00 [032] - De-Energized Performance Too Early
Intermittent - Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00100000
Fault Priority: 0
Fault Frequency: 0
Reset counter: 0

I ran a log of misfires while I drove around last night and I am misfiring on all cylinders while in 93 mode, but only under load. I still don't misfire in stock mode. My car only has 40,000 miles so it makes me think it was something the APR dealer did when then had to bench flash my ECU.

Hokie07

Well, turns out it was a bad fuel injector. I was driving yesterday and my car started misfiring like crazy, and the CEL began flashing. I had to pull off the road and get the car towed to the dealer (free thanks to Audi roadside assistance). They're working on it now, and my car is still under warranty. Hopefully I don't have any more problems after this. It's just surprising that a fuel injector could go bad after only 40,000 miles.

willydimes

just out of curiosity, does your dealer know you have APR programming? Do you switch to stock when you bring it in? Thanks

_Stormin_

The blessing that is the factory warranty...

Hokie07

Well Audi rejected my warranty claim for the fuel injector. The dealer knows I have APR tuning and doesn't care, but the "TD1" code came up so when the dealer submitted the warranty claim, Audi of America said they won't pay for it. I talked to the tech who worked on my car and he said there is no way the APR tuning would effect my fuel injector. Unfortunately, even though my APR program was locked out, Audi still found out about it because they use a software that checks for the file size of the ECU software. I apparently was the first person at my dealer to have this happen, lucky me. Because my fuel injector failed open, it sprayed fuel everywhere so I had to have my spark plug and coil replaced for that cylinder, which also wasn't covered. I'm just lucky I didn't damage my catalytic converter. It was a $700 out the door, merry Christmas to me. I'm fighting this with Audi of America, someone is supposed to get back to me next week.

Hokie07

Ok I don't know what's going on. I put my car back in 93 mode with APR and it is misfiring again, on all cylinders, only while I'm accelerating. I also hear a clicking noise while it's misfiring. Not enough to throw a CEL though. It's not misfiring in stock mode so I'm going to keep it that way until I can figure out what the problem is. Does anyone have any ideas??

_Stormin_

The fact that it's only misfiring under the APR program, after the repair, really pushes me to believe that it's a program issue. And oddly enough, the fact that you had a single failed injector, but were misfiring on ALL cylinders, doesn't make a whole lot of sense in general. Was that injector somehow feeding fuel to the other three cylinders as well?