Does this O2 sensor look toast to yall?

[BlackGMC]

I am trying to help a buddy get his truck running after years of down time... Sorry i don't have the tune but this is a quick log he sent. You can see the Bank1 O2 sensor starts to switch like it should once the temp gets up, but the bank2 02 sensor is all over the place the entire log... Also notice the LTFTs of each bank...



8921

[BlackGMC]

anybody?

[swingtan]

The O2 switching looks very fast for the first section of the log. Both are doing it which makes me think there could be a wiring issue, or something like that.

At frame 1992, the O2 for bank 2 comes good and starts behaving as normal, at the same time the LTFT's drop rapidly. The O2 for bank 2 however still switches very, very quickly. Much faster than it should.

My assumption is that there is something interrupting the O2 signal voltage, which is telling the PCM that the engine is running lean (as a low voltage from the O2 = a lean condition). It could be that the O2's have blocked up a bit from siting for so long and me need a bit of a run to clear out the gunk. Then again, it could be that a number of cylinders are not firing correctly and are messing up the exhaust mixtures and the O2's are actually working fine.

If it's easy to get to the O2's, I'd pull them out and have a look. If they are a bit difficult to get to, I'd pull the spark plugs and check the ignition system first. Chances are though, that both will need looking at. I'm also assuming you have put fresh fuel in there, flushing out any old stuff.

Simon.

[BlackGMC]

thanks for the replies. I guess i should have added some more info... Both O2 sensors are brand new. my friend was having a hard time getting it started. So some bad gas made it's way threw the fuel system... He then flushed out like 3 gallons of super bad gas, threw the shrader valve on the fuel rail... Then he added 10 gallons of 93 octane. Then he finally got it started however it was running pretty rough, eventually it smoothed out, but it has a miss we you start to rev it up...

[Chuck L.]

"running after years of down time"...
Common problem[s] w/ "miss" & engines having set for yrs... Gummed up injs.
I see this frequently on junk yard engines. [The owner sends me his problem injs for cleaning]
Filter sock in the tank can be nasty.
Main fuel filter can be nasty.
Filter baskets in the injs are full of crud.
A quik check for major problems: Pull the injs and see if the tops at the o'rings are rusty. A rusted inj is JUNK!

A cheap test: Add some Seafoam, and see if the miss clears up. If so, it would be a good idea to have the injs cleaned and flow tested....