Radcannon

iTrader: (3)

OK here is the issue. I just picked up a 94 TA Supercharged but it isn't tuned.

I was driving it took it home shut it off. Got in it the next day to do some data logging and backing out of the driveway I noticed the on my separate wideband sensor that it was running super lean on the driver bank. So i opened up my tunning software and the o2 voltage was at 60mV on the driver and 550 on the passenger.

I then started pulling plugs and checking injectors. I got the driver plugs out all but 1 and they are covered in carbon and the electrodes are all bent with some cracks on the center porcelain.

The passenger side all look normal and are not that carbon covered at all. No cracks and very minimal distortion on the electrode.


What the hell is causing this???? Spark is at 25 with 8.7 compression and 7-10 psi of boost. The thing hasn't seen boost though with me at least.

Should have compression results this evening.

gregrob

iTrader: (8)

fubar

ss.slp.ls1

iTrader: (36)

Exaust leaks?
Bad o2's?

Radcannon

iTrader: (3)

Its not tuned but that doesn't matter. Any serious differential between o2 voltage like that at idle or any speed is severely wrong. The computer will adjust ltm's and stm's to get the fueling around 14.7 and both banks of o2's to switch.

There are some exhaust leaks on the very lean side. The collectors are slip on collectors. And when i was just under the car looking things over i noticed alot of soot out of it and i shook it and it wasnt fully seated but I don't think its bad enough to read like that (I was thinking of trying a silicon sealer on it but I dont know). Because when I fired it up and let it get a little hot and sprayed it on the cylinders the back two were cooler than the front two by enough to take a while for the water to evaporate instead of boiling.

I am replacing O2's and plugs right now too.

ss.slp.ls1

iTrader: (36)

Nice. I'd definitely do something about those exhaust leaks. They could have made your car run rich and fouled out your plugs and o2, making the situation worse.

Radcannon

iTrader: (3)

Wow.... The biggest pain ever to change plugs and do a compression test. Took me 5 hours so much had to come off.

Compression check.
Cylinder PSI
1 130
2 146
3 128
4 140
5 130
6 140
7 127
8 145

Looks like bank one went a little lean and hurt the rings. I am going to check the rings tomorrow with oil. Will this be ok and should I just move on?

Also found that the o2 sensor connector to wiring harness fell out and hit the exhaust and melted it. I still don't understand why the car wouldn't dump fuel to compensate though as in why my wideband in that bank went lean too. Its wiring was fine so I know it was lean and yet my plugs were completely carboned in that bank. Anyone shed any light?

The only thing I can think of is that it shorted the heating circuit which it looked like it did and the computer was looking at the resistance and saying it was to hot or cold and doing something with fuel then.

Radcannon

iTrader: (3)

OK. completely solved. Engine is fine nothing to worry about large cam and maybe some slightly damaged rings but its ok. The wideband was running lean but spiked rich momentarily as the pcm compensated and then caused rich misfire to occur. The unburnt mixture then caused the o2 to read lean to because misfires will cause that.

Spark plug electrodes need to be adjusted so its on the top. A few of them hit the cylinder.