Cylinder 3 Misfire, Too Rich, Help Please

white 2g awd · 06-04-2004

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!

TheBlizzard · 06-04-2004

Not having a second O2 sensor will not make the front one read any different, it should throw a CEL though. I don't remember if you are using a logger or not, but if you are do some low throttle pulls and log them and see what it is doing. You can't really trust the stock O2 sensor anyway but it will give you an idea where you are. Sometimes you have to lean it out a lot to see some results, it sometimes seems like it is not doing anything but it might be that rich. So is the car missing at low throttle? When is it running bad? Is it boost related? Be more descriptive.

Just a little pointer, you should give your lists of mods to people, it will help you get answers to your problem.

Craig

white 2g awd · 06-05-2004

sorry, had my mods listed in my profile, but here they are full dejon hard pipes, 1g bov, walbro 190, 550's, safc, keydiver chip, rnr o2 elim. dp, thermal catback, evo 3, act 2600, hrc smic, the car misses at idle, and low throttle, wot is good, i start getting the cylinder 3 misfire at cruise on the interstate usually. basically should i lean it out more till i get knock on low throttle, then richen it some to take it out, so that its on the verge (can't spell) of knock, or what?

Dustin

TheBlizzard · 06-05-2004

You can do that if you think that it is a rich miss, however it might not be fuel related. If the car is not knocking right now you can play with the AFC and see if you can tune the miss out of it. Just keep a mental note of your original settings so that if it is not the problem you can put the AFC back to its original state.

Try to tune it out as if it were a fuel related problem, if thats not it, then repost what it did when you messed with fuel and we can take it from there.

CRAIG

**Goat Blower** · 06-05-2004

Do a compression test on cylinder #3.

white 2g awd · 06-05-2004

allright, well i tuned it out, not getting any knock, i had a compression test 3 weeks ago, scored almost perfect, so i know its not the valves, took the car on my road trip today, and well, me and my dad will be taking his truck and car trailer on a 150 mile drive tomorrow, i'm probably going to put some new spark plugs and wires on it, if that doesn't fix it, i'm selling the pos and buying a camaro. it was puffing white smoke like there was no tomorrow, fuel trims were -14% both stft and ltft when it was doing it, i turned my safc all the way to -15% and didn't do a thing. so i'm going to assume that my #3 spark plug wire is bad, try putting in some new ones.

Dustin

oh yea, i tuned so that both fuel trims were 0 before i took it on the road trip.

white 2g awd · 06-07-2004

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

**JET** · 06-07-2004

It is not real common to have a bad injector in a DSM. Especially if they are Denso's. RC's aren't quite as good, but still pretty reliable. Are you losing any coolant? It sounds like it could possibly be a blown headgasket too with all of the white smoke. Wires go bad pretty often on DSM's, so that is definately the first place to start.

white 2g awd · 06-07-2004

i haven't checked the coolant yet, but with a blown head gasket, wouldn't the compression be worse since it was blown??? and i know its leaking tons of oil, my oil return is leaking a little bit, i will have mitsu check that tomorrow though, and i had them put in some new spark plugs and spark plug wires today, cause they were the only ones in des moines that had any of either in stock. i hope it's not a blown head gasket, most boost i've ever run on thsi was 19psi with my evo 16g that i have now. thanks for the help, also, do you think that this injector could be the problem, it kinda seems logical to me, cause the mitsu guy said it was spraying all the time, that it was just stuck open, and every time this happens i can't start my car, i pop the hood, and i can smell the gas, in the engine bay, like its not getting burned, does this sound right? thanks for your help.

Dustin

**JET** · 06-07-2004

All of the symptoms seem to support the bad injector theory. I would give that a shot if the wires didn't work.