OT: Fouled up spark plug ...

[Garry]

After getting my car out of winter storage, I've driven it twice ... one time some 120mi, the second something like 200mi ... on the first trip, I already suspected higher fuel usage, but attributed it to the fuel tank being not completely full when I put it up, and some starts in between ...
Anyway, on the second trip, I started out with a full tank ... I barely got 80mi down before the fuel gauge was down to 3/4 ... Now, I usually get well beyond 100mi (more like 120+) out of that first quarter (F-Body fuel gauges are very non-linear), so I knew I wasn't running right ... didn't feel like it had any problems though ... (apart from the WBO2 delivering weird numbers ... afr of 30-40 ... most likely dead)

Finally got the car on the lift yesterday evening and started by pulling the two O2 sensors ... driver side (stock NBO2) looked pretty much normal, no lose residue ... but the passenger side one looked black as coal, generous layer of residue on it.

I then took a look at which spark plugs I could pull from the passenger side, and the rear one is just about the only one I could manage to get out ... (d@mn long tubes ...) Turns out it looked pretty similar, black residue, but apart from that the plug looked fine. Also noticed some fuel on the treads of the plug. Gap is about 1.5mm, which I compared to one plug from the driver side, same gap there. And no residue. I now swapped the two as a first step to see whether the formerly fine plug from the left will also get the residue ...

I don't know the state of the other plugs on the passenger side, for now I just hope they are NOT having a problem, as it would most likely require me to pull off the header.

Any suggestions what might be wrong, what to check for?

Help appreciated!

[joecar]

Garry,

Check for airleaks in the PS header (from the head flange to about 12" past the O2 bung in the collector), and on the PS side of the intake manifold... extra air may be causing the PCM to add fuel to maintain trim... what does LFTF2 look like...?

Do you have some log files...?

Is your wbo on the PS (bank1) or DS (bank2)...?

If the PS injectors were leaky, then you would get a similar result but the wbo would show rich.

[Garry]

I'm running SDOL ... so I reckon the FT shouldn't mess up the fueling ...
WB is on PS ...

[joecar]

Then maybe there's a leaky injector on the PS.

If there's unburnt fuel then the wideband will show lean.

Attach a pressure gauge to fuel rail, and cycle key-on/off several times to build pressure, should stay steady for a minute or so.

[Garry]

Well, turns out the whole PS bank was running rich, due to the WBO2 being shot after all ... PCM saw the lean condition and added fuel to compensate (thought the O2 were off due to OLSD) ... car seems to be running fine again after I through out the WBO2 and put in the stock NB again ... guess I need a new WB ...