eteller

Ok, here's what I've got:

2000 T/A A4 54k mi. w/LT headers, no cats, cat back, new Frost tuned PCM (same problem with original PCM), lid, ported TB, roller rockers, NGK TR55 plugs, MSD wires. Car is in great shape, and runs great normally.

Driving home in the snow a few weeks ago, car developed a bad miss at idle every other day or so. It clears up at about 1/3 throttle. Changed plugs and wires, no help. Washed the car and engine the other day and it is now almost constant. Occurs a few minutes after starting and will go away once warmed up but will reoccur on restart warm. Figured I got something wet so disconnected everything and sprayed the connections with MAF cleaner (cleaned MAF too). Checked all vac/pcv lines, plug wires and looked for arcing, everything looks good. Same problem today. Have new 13111 O2 sensors on order as mine are spliced but it's not throwing any 02 sensor codes just P0300. Ideas?

Big Black WS6

I'm currious to see what fixes your situation.. I recently put on LT's (no cats) and ran it through my old exhaust. I also am using MSD wires and NGKTR55 plugs, New Bosch o2's in the front, none in the back. Getting a tune from frost tomorrow. I was throwing the air/egr rear o2's P0300 and mass airflow.. Just got my parts in, SLP MAF and SLP loudmouth catback. I have the exact same symptoms your having.

eteller

All my emissions crap has been tuned out. My 02 sensors are suspect as their spliced by the previous owner but I do not see them getting wet from washing the engine from the top. It's weird because the throttle is like a switch now, it hit's a certain point and it's normal. It makes me want to change the TPS but their are no codes for it and it looks fine with a volt meter. It seems very temperature dependent too. It will not start missing till the engine it somewhat warm (Hmm, that does point to the 02 sensors, I think they kick in once warm and it goes to closed loop, right?).

Big Black WS6

Personally I would double check them, especially since they were spliced by a previous owner. If you do need new ones i would go with the Bosch replacements. In fact i had wierd issues concerning weather. In the early mornings (below freezing) it would run fine, but after work (40+) it would run horrible. But I also have constant misfire...

eteller

Got a new set going on Saturday, Bosch 13111's via Amazon. I have no idea the condition of the ones on the car, but I do see electrical tape where they were spliced, prolly when the LT's went on.

eteller

Forgot to add the car has had three cans of Berryman's B12 through it since November when I got it, a new fuel filter and fuel pressure tests at 55-60 psi.

eteller

Alright got some data of sorts! HELP!!!! Now that the issue is easier to duplicate I got home (it started after about 3/4 of a mile then quit when I goosed it for the rest of the 15 mi ride home) cranked it up and waited a few minutes, it started. I have a temp gun and the whole passenger side headers were at around 215-240F the drivers side was 450ish. Unplugging the gray coil plug for the whole bank that did nothing, as did unplugging a few injectors I could reach (2 and 6). I tested #2 by putting a bolt in the boot where the plug goes and it jumped a 1" to ground (although I shut off the car to rig up the test rig so I'm not sure if it was missing then or not). I'm thinking it's the passenger side 02 sensor telling the bank to go full rich and cooling the headers down? The exhaust kinda smells like gas and my mileage has not been great.

Big Black WS6

Well, today I got my PCM back from FROST and got my SLP Mass airflow on and all I can say is WOW! It's a whole different animal! No more P0300 Code, Air/EGR, and rear o2's... I'm not sure if this helps at all, but it seems to me it was more of a MAF problem on my end.

eteller

Glad you got it fixed. 02 sensors will be here tomorrow, hopefully that's it.

eteller

FWIW Looks like it was the 02 sensors, one was loose, both were sooty black.