misfire diagnosis help.
misfire diagnosis help. 94 trans am pacesetter headers(with ERG/AIR emissions)/ory/borla meziere electric water pump, when i replaced the headers i installed new plugs and taylor OTVC wires. Has a brand new opti on it. I did a spark plug/wire test and all the wires are getting spark. Fuel pressure is perfect at 43 key in "on", idling drops 3 to a 40. I am getting a bad misfire at both idle and at acceleration. I have checked and double checked all of my wires and everything seems fine but i have no idea what the problem is, this is pissing me off, i finally get the damn opti replaced and i cant drive the damn thing because of the misfire.
Come on guys, give me some ideas, it has a brand new coil, would not have a LT4 knock module cause the misfires? I seem to be running sluggish like im running on 7 cylinders but every plug/wire looks good and are clamped in tight. Would bad O2's cause this? im not throwing any codes, would i need a tune or something? Come on guys im getting desperate here.
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Fuel filter, and yes the LTs usually cause a knock from clanging against stuff. O2s also would cause it. So many things to do, but w/o having it scanned and/or data logged, it's hard to tell.
Originally Posted by fergymoto
Check your firing order then check it another 3 times. Then go out in the dark and start it up and look for sparks, could have burnt a plug wire.
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okay here is my plan, what i think is going on is i am getting a boat load of knocking which is screwing up my timing, so i have an LT4 knock sensor on the way which hopefully will smooth things out, but i think my main problem is that the car is dumping way too much fuel in, because i can smell it and it is really rich, plus the car will idle for about 15-20 minutes without any backfires or anything and then just dies like it gets flooded or something. So i will see how the knock sensor goes and then maybe try a tune here and see how that goes.
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Some of you guys don't understand this lt4 KM thing. The lt4 knock module (not sensor btw) is something you can use to get rid of FALSE KNOCK, i.e. there's no real knock going on, the sensor just thinks there is and pulls timing. Basically, there is no problem with your engine, the knock sensor just creates an artificial problem.
If you have a misfire that you can actually hear/feel, then you have a real issue and an lt4 knock module will do absolutely zero to help you with that.
In summary, an lt4 knock module will not fix real engine problems. i.e. misfires, rough idleling, audible knocking, etc. The only thing an lt4 knock module will do is sometimes reduce knock retard due to a false knock condition, and even in that case it's usually less effective than tuning which is the better solution.
If you have a misfire that you can actually hear/feel, then you have a real issue and an lt4 knock module will do absolutely zero to help you with that.
In summary, an lt4 knock module will not fix real engine problems. i.e. misfires, rough idleling, audible knocking, etc. The only thing an lt4 knock module will do is sometimes reduce knock retard due to a false knock condition, and even in that case it's usually less effective than tuning which is the better solution.
i had the same problem on my dads lt1 and we found that one of the pins on the opti wire harness had pulled loose and was not seating properly. just some thing you might want to look at.
Originally Posted by infinitebird
Some of you guys don't understand this lt4 KM thing. The lt4 knock module (not sensor btw) is something you can use to get rid of FALSE KNOCK, i.e. there's no real knock going on, the sensor just thinks there is and pulls timing. Basically, there is no problem with your engine, the knock sensor just creates an artificial problem.
If you have a misfire that you can actually hear/feel, then you have a real issue and an lt4 knock module will do absolutely zero to help you with that.
In summary, an lt4 knock module will not fix real engine problems. i.e. misfires, rough idleling, audible knocking, etc. The only thing an lt4 knock module will do is sometimes reduce knock retard due to a false knock condition, and even in that case it's usually less effective than tuning which is the better solution.
If you have a misfire that you can actually hear/feel, then you have a real issue and an lt4 knock module will do absolutely zero to help you with that.
In summary, an lt4 knock module will not fix real engine problems. i.e. misfires, rough idleling, audible knocking, etc. The only thing an lt4 knock module will do is sometimes reduce knock retard due to a false knock condition, and even in that case it's usually less effective than tuning which is the better solution.
Mike, thanks i will check out the opti harness tomorrow.
Originally Posted by GGPC
Did you set the timing to dead center zero when you put on the opti? Even though it is slotted and can only go on one way, The #1 cylinder needs to be all the way up. Old school way of doing it.
Originally Posted by transambandit
yes and the header install i did could very well show a boat load of false knocks thus causing the engine to run rough, i dont intend for it to fix the misfire, i believe the misfire is probably related to needing a tune because my car is running very very rich. But the LT4 will definitely help make the car run smoother if it is not sensing a butt load of knocks from the headers. Eventually i will get a tune but i want to do an LE2 or LE3 head/cam so i would waste my money doing a tune now, unless i buy my own software and tune it myself. that is.
Mike, thanks i will check out the opti harness tomorrow.
Mike, thanks i will check out the opti harness tomorrow.
well i started it again tonight and looked ever so closely and i did notice i am getting a slight spark from #4 on the passenger side, so either that is my problem right there and it needs a new plug/wire or im still going to be up **** creek without a paddle. I do know that it is very close to the header there so maybe that is the problem.
