Osmosis

Hello from P300 hell! I was on a work trip, car sat @ a park and ride for 2 weeks. Got back in the car with no changes to the odometer but the car was running a bit rough. Once I got home, next day, sounded like the car had a huge cam. Obvious misfire. Then< finally got the code p300. Now, my car shudders @ highway speeds or idle. I figured it was bad plugs. changed them with plugs gapped the same as the old @ .028. No change with new plugs. Old plugs looked OK. Now I'm wondering WTF? Is it coil packs? I'm not getting any other codes? I'm using tuner pro rt. Any ideas how to identify what is causing the problem. A generic P300 code does not help much if anything other than a guessing game Help please

4Driver4

Look at the misfire counts for each cylinder.

Osmosis

tuner pro is only showing me P0300. earlier today, I did see two misfire codes from cylinder 2 and 5, but nothing other that that. After I got that code, all I get is p0300

Osmosis

Well, tuner pro sucks for my Audi, great for my truck.

Anyway, I was able to find an old laptop that has Vag Com Lite on it and pulled the following codes;

P0300
P0302
P0305
P0306
P1624

I assume that the 302-306 represent cylinder misfire in cylinder 2,5, and 6. I had changed the plugs to new plugs with gap @ .028 as I always have had in this car. Now what? How do I confirm the coil packs are working or not?

Thank you all!!!

Osmosis

Well, I purchased some coils off of amazon for 77 bucks. That...was a waste of my money! I was sure it was spark plugs, 45 bucks...Nope, then I thought it had to be coil packs. I cleaned the connections with Electrical contact cleaner, changed out each coil pack with no change.

Now, my car runs like it has a cam in it @ idle up to 2500-2800 rpms. Yes, I know the cam sound is misfiring cylinders for some reason. above 3K rpms, it seems to run OK.

I used some Mass air sensor cleaner and cleaned the MAS...still no change!
I also sprayed brake cleaner on connections looking for a vac leak, nothing found

I got a P0300 again with P0305 cylinder 5 misfire. At this point I have no clue and i"m tired of throwing parts at it.

I did gut my pre cat's and don't ever see an O2 sensor code error. I"m wondering if It is my O2 sensors?? Down stream in particular??

Anyone? I need some help!

meternerd

Downstream O2 sensors (Bank x, sensor 2) have nothing to do with performance. They are just for sensing an inefficient cat. If you aren't getting codes for O2 sensor 1, I'd look elsewhere.

johnkk

Assuming this is your 2000 2.7t.. For vacuum leaks, I use propane or carb spray to check. Not sure about brake spray.
If OK at cold start, but problems appear when warm and in closed loop, that points to MAF. Try unplugging the MAF and see what happens. If runs OK unplugged, replace MAF.
Maybe coolant temp sensor.
Swap spark control module connectors and see if misfires flip to opposite banks.

Osmosis

New Plugs and new coil packs on all cylinders. No change!
I spayed brake cleaner on vac lines, no identifiable changes.
I pulled the MAF connectors off and it ran worse, plugged them it and ran with no improvement. I purchased some MAF cleaner, hit the MAF and terminals with no change to the said problem

The car runs like it has a huge cam but it is all stock plus the APR stage 1 tune. I"ve swapped back and fourth to the stock and stage 1 tune with no change in idle quality. Once I get the car above 2800 rpms it runs smooth. Anything from idle to 2800, it shakes and shutters while driving.

O2 sensors are the only thing I can think of from here???

Anyone have any ideas?

drpancho

I would do a compression test, to rule out any hardcore problems before spending more money.

Harleyguy

As was mentioned by another, brake cleaner won't work. It doesn't have the volatility of carb cleaner and doesn't combust well under compression. There is also the possibility that you have wiring issues at the coil connectors. This assessment is based on the faults you detected because they specify individual cylinders.