cylinder 3 misfire, too rich, help please.

[white 2g awd]

allright, took my car to mitsu, driving to work i got a cylinder 3 misfire, and it wouldn't start after that, so i had it towed, they said everything was fine, coilpack, plugs, wires, all that, they said i could probably use a new set of plugs and wires, but they said that it was misfiring cause i was running so rich probably. they said my fuel trim was at -4.7, guessing my ltft, cause that one has been off a little, now, i have 550's and a 550 injector compensation, i messed with it some more today, my low thr. settings on the safc are at -8% across the board, my stft is 0-3 fluctuating, and ltft is at 0 now, i've leaned out the hi a little as well, now my question is, should i keep leaning it out on low throttle till i start getting knock? (can view with knock conversion on keydiver chip). or should i just watch fuel trims, i'm going on a 300 mile road trip in 3 days, i can't afford to have it break down again on the road in the middle of bfe. and i can't rely on my o2 volts at wot, cause they are reading low, i'm not getting any knock either, o2 1 is reading around .90 to .92 with no knock, mitsu said since i have no cat, that the rear o2 sensor is getting screwed up, then in turn screws up my front one, is this true??? thanks for all the help, i really need to get this fixed soon!

Dustin

 

[1fast97gsx]

You shouldn't be throwing a light if you are only like 4.5% off. As long as stft and ltft are +-10% you should be fine. Maybe the injector is just going? I was getting a similiar code and my injector harness kept popping off because the tab is broken. If you changed the plugs and wires and the coilpacks and ignition module are fine all that leaves you with is a bad injector and some internal damage ... but if something was messed up inside the ecu probably wouldn't be smart enough to recognize it's cylinder 3 that's having problems.

 

[white 2g awd]

spark plugs were changed as of last saturday, injecotors have about 3k miles on them, compression tests perfect, harness is nice and snug every 3 or 4 times a day i check it, thats why i think its running rich also, they said my plugs were black, which my old ones were too, and i have about a 4 inch black circle on my bumper around my exhaust tip which makes me think its rich too. so should i lean it out more till i get knock, then richen it a tad, (just on the verge [can't spell] of knock)?? or just follow my fuel trims???

Dustin

 

[1fast97gsx]

low throttle you set using fuel trims. High throttle you have to log timing advance and O2. Just use the O2 to get in the balpark ( .92V imo ) and then tune for good timing advance. Try leaning it out more and more until timing gets pulled .. then richen it back up a tad. You are definitly running rich, however I don't think that would throw a "Misfire" code. It would come up as " O2 bank 1 rich condition" or something along those lines. A misfire code is only if it physically misfires, like either no spark, or no fuel. Nothing else I have heard of would throw a "Misfire" code. If new plugs and wires don't do it that leaves coilpacks, ignition module, injectors, and ecu. I guess just keep narrowing it down but try and lean it out a little and maybe it will fix it somehow.

 

[white 2g awd]

well did it again today, going to take my dad's truck and trailer on a 150 mile drive tomorrow, i'll try putting some new spark plugs and wires in it monday, if that doesn't fit it, then i'm just going to sell it and get a f-body.

Dustin

 

[kpt4321]

If you changed the plugs and wires last week and that didn't fix the problem, it won't fix them this time either.

 

[white 2g awd]

changed the spark plugs last week, not the wires, the plugs were shit platnum ones, thats all i could find anywhere near me, mitsu said that the platnum ones might run a little hotter, so it won't help, and it could be the wires, but i got to looking today, in the chiltons one cause of a misfire is wrong tension on the valve springs, this started when i got my new lifters and turbo put it, the valve springs will lose there tension while putting the new lifters in right? then put tension on them when putting the lifter back in? maybe they did something wrong along those lines, so i'll talk to them about that too, anybody know how much tension they should have?? thanks for everybodies help so far.

Dustin

 

[white 2g awd]

allright, found out today, my number 3 injector is sticking open, so mitsu thinks that its flooding that cylinder and not sparking, which would also explain why my car has been running so rich lately even with my 550 compensation, so i have some 650's coming tomorrow. Question though, an injector sticking open, is there anything that causes this? Or is it just a shit happens type deal.

Dustin