hey guys-
just got home. the o2 sensor (singular, the other is ziptied out of the way, against the frame) is practically new. i drove all the way back from el centro to san diego (about 120 miles i guess) towing a trailer without boosting. it about killed me, i tell ya.
anyway, in el centro i swapped out the plug i had in #6 for a new plug, and since my wires were looking a little old (original set on an 01) i threw a new set on there as well, thinking that would cure the problem and i could go merrily on my way to making fresh Glamis tracks.
No dice.
the stealership in el centro only had the stock plugs for the 5vz, so that is what i installed, but the plug i took out looked in perfect condition. (it only has about 3000 miles on it).
it only threw a CE light once, a short time after the problem started, and not since then. I happened to have my reader and manual in the truck, and the code came back as "cylinder 6 misfire detected". I can feel a loss of power, mainly from the fact that when i get above 0 psi on my boost gauge, and i mean even 1/2 psi above 0, and the engine shakes so that it vibrates the whole truck. It very very very seldom happens below 0 psi while driving, but will miss while idling.
At idle it sometimes revs up and down, as if trying to find the proper air/fuel mix. could it be that the o2 sensor is telling the computer to adjust all over the place to compensate for the sometimes-richness that would come from a misfire?
I sure as heck hope it's not a cracked head, but i'm ready for anything.
i have a cylinder compression tester, and once it cools down a bit I'll check the cylinders and report back what i find.
FYI i've had that weird idle problem (sometimes revving up and down) for some time now, and I always attributed it to running 440 cc injectors and the ecu not being able to control them that well. Now the problem seems to be exacerbated and I'm ready to finally to figure it out once and for all.
oh one more thing...while this was going on, and the whole way home, fuel pressure was steady, oil pressure was steady, temp stayed dead center, and I checked the coolant for oil and vice versa. Both clean and at their proper levels. Oh, and the EGTs were right where they've always been...800 at idle, 1200 crusing, 1300-1400 TOPS when boosting...just as they were five minutes before this problem occurred. EGT reading taken an inch and a half from the exhaust port on number 2 cylinder header runner.
-Elsensei