TImmy_Jones

iTrader: (4)

So the dreaded lean code, could be SO many things....


I want to make sure the P0174 is the passenger side, correct? Strange it is only on 1 side, so i am ruling out vac leak FOR NOW, as I sprayed some carb cleaner near the lines and felt no changes.

Here is the quick story...header install, zip tie melted, O2 wires fell on header, burnt the wires and unfortunately the clip, so I cut wires upstream, run new wires down and splice in. Unplugged the battery and fire up the car...

Get the two codes, do you think the O2s were so bad and dumped so much fuel, it fouled out the plugs?? This diagnosis fits for the P0300, but does it make sense for the P0174? Should I replace plugs first (brand new with header install and new wires) car ran perfect until about 50 miles ago when I investigated and found the melted wires.

Possible the O2 sensor is bad? it was covered in black soot when I pulled it, but wouldn't explain the misfire...

Where to start? Pull a plug and check it, would plugs coated in gasoline/ran rich for 50+ miles 'foul' and cause a misfire/lean code?

Any insight would be great! All mods in sig, with frost mail order tune.

Headers are about 200 miles old and tune is about 30-60miles.

TImmy_Jones

iTrader: (4)

So I pulled the front plug on the passenger side and it is BLACK, covered in soot. Fouled plugs??

I cleared the SES light and it has yet to come back on, after warming up.

The car has a slight mis or like chugging sound to it, I guess I have to man up and try and tackle those stupid plugs.

Gonna pull the AIR system and coil packs today.

Am I wasting my time? Should I buy new plugs or clean these ones?


the plug looks like this::

RPM WS6

iTrader: (3)

Those codes could have been due to poor readings or poor A/F management when the wires melted. I would assume they were left-over DTCs from the damaged wires when you first got it running again. They may have been pending before the restart.

Now that you've cleared the PCM, I would only worry about any new codes that you see with the repaired wiring.

In the mean time, I would just get a new set of plugs. That's extremely carbon fouled, and could certainly cause some rough running.

TImmy_Jones

iTrader: (4)

Old plugs out and they all look like that on passenger side. Pulled #1 from the drivers and it looks clean, phew! All new plugs ready to go in tomorrow. I'll report back.

Thanks RPMs, nice to hear from the big dogs on here who know their stuff.

Frost

iTrader: (45)

The dark plugs on one side mean you found the side with the misfire (and possibly the root of the lean code). The PCM is a bit stupid here... When a cylinder misfires, it sends unburned oxygen out of the exhaust vale and it makes it's way down to the O2 on that side. The unburned oxygen 'looks' lean to the PCM so it adds fuel and adds fuel and adds fuel because it thinks it's trying to fix a lean condition, but it never can. What it CAN do is cause serious over-fueling on the side with the misfire if it's driven like that. That's what you are experiencing.

TImmy_Jones

iTrader: (4)

Well, found some NGK TR55s locally, gapped em at .060 and they are going in tomorrow. Hope to report back with some good news.


Thanks for the re-assurance Frost, also incredible turn around time on my PCM, can't wait to actually enjoy it with a car that runs right and not dumping fuel in for nothing.

TImmy_Jones

iTrader: (4)

New plugs installed, car runs awesome!

No hiccups, pulls hard, sounds better, idles smoother.

Thanks for the help. And Frost, thanks for the tune!

TImmy_Jones

iTrader: (4)

And for anyone afraid to tackle a plug/wire job on these cars is crazy, everything was done with a regular plug socket and a small swivel extension, just remove the AIR tube and the front 3 are easy, backs can be done form under the car.

Maybe headers makes this install easier??

RPM WS6

iTrader: (3)

Glad you got it sorted out.

The #8 plug is something I've always done from the top, with or without headers. I just pull the AIR tube and remove the coil rail ('99+). For the '98, I don't even remove the coil pack.

Honestly I don't see how people do it from the bottom. That seems impossible to me.

TImmy_Jones

iTrader: (4)

How tall are you?? I would have to have arms like a drinking straw to get in there, haha.

I am only like 5'10 and I have some skinny forearms and COULD NOT get in there.

Honestly, of all the plugs the #4 plug was the hardest and the back one was the easiest once the car was in the air and the tire was off.



I don't know who said this one here, but someone was like, "just stand on the battery for the #4 and #6 plug", holy crap did that make it easy, seriously the angle lets your arm slide right in, I even hand my second arm in there, under the plug to guide it in.

jblack245

i kept having this problem after my header install. this would happen to me once a year on average and only on the passenger side. i was running with the corvette bosh 02s and that was my problem. they work for some but not me. i have a scanner and every time this would happen the passenger side 02 would die. i changed out thoes with denso 02s and never had the problem again.