Miss Fire
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Joined: Oct 2005
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From: Lexington, NC
Mis Fire I have a 94' Z-28 with 92000 miles on it. When running the car up in the RPM's it pulls hard up till around 5000 then the thing starts to backfire and miss. I am thinking that it might just be trash in the injectors or in the fuel filter or something and it just starving for fuel.
Another thought was the the spark might be retarded... not exactly sure. Anyone else had this problem with the LT1's.
Another thought was the the spark might be retarded... not exactly sure. Anyone else had this problem with the LT1's.
Last edited by bmccrary; Nov 10, 2005 at 03:27 PM.
optispark all the way.i am 99% sure optispark.my budy has a 94 33,000 mile trans am and his done the same last week and it was the optispark.changed it and now runs like top but someone might have different opinion.
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Joined: Oct 2005
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From: Lexington, NC
call me stupid, but what is opti-spark?
At about 50000 we had the crank trigger replaced because the waterpump was leaking back on to it and causing it to miss under any load, but it never back fired then.
At about 50000 we had the crank trigger replaced because the waterpump was leaking back on to it and causing it to miss under any load, but it never back fired then.
Teching In
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From: apollo beach florida
stupid hey mr. stupid, no offense, your optispark is what the cam driven distributer is, its called an opti because its optimum for the lt1 and the ls1 and all that, throw some injector cleaner in there for the hell of it, i recomend the lucas brand injector cleaner, redline products are backed by gm, so feel free go nuts, your opti could be goin bad but fix the cheaper parts first
The last LT1 I dealt with that had those symptoms badly needed spark plug wires. If they are stock, or just havn't been changed in a long while, do yourself a favor and replace them first, even if they "look" fine. Might as well get some new plugs in it while you're at it, they're cheap.
...to the person who said opti is for optimum.... uhhm, no. and they don't use them on LS1's either.
it's called an opti because the distributor uses an optical sensor inside it....
...to the person who said opti is for optimum.... uhhm, no. and they don't use them on LS1's either.
it's called an opti because the distributor uses an optical sensor inside it....
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From: Lexington, NC
yeah crank trigger, old drag racing term. I put some fuel system cleaner in it, and it seemed to help a bit, but it still acted up. Like I said though we had the opti replaced in it when we replaced the water pump. But I am going to go price some plug wires and plugs. Dad and I might possibly attept to change them out. I am expecting lots of language on that day.
Any recomendations on some good wires, MSD? Any others?
Any recomendations on some good wires, MSD? Any others?
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From: Lexington, NC
When I was at AutoZone checking prices on plugs and wires I came back to my car and the security light was on! Ignition was dead! I was pissed. I went into the store and asked what was going on, because I have never seen this before. He told me that I would have to call a hook because that was the only way it was leaving the parking lot. I walked back out there and it fired right up. He fed me what I felt was B.S. and I left.
If this happens again, is there anyway I can reset the computer so it will work. Will pulling the positive side of the battery loose reset it and shut that off if it happens again?
If this happens again, is there anyway I can reset the computer so it will work. Will pulling the positive side of the battery loose reset it and shut that off if it happens again?
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mine was doing the same thing except it kept on getting worse , i almost replaced the opti but my plugs had oil on them so it ended up being a bad intake manifold gasket which oil was getting into all of my ports, check ur plugs.
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From: Lexington, NC
Well today when changing the oil, I put some sea foam in the intake manifold and the rest in the fuel tank. I enjoyed foging the neighborhood for misquetos.. but the best part is that the missing has gotten better... instead of missfireing at 4500 or so, it starts at over 5000 and gets horrible and will not rev any higher than 5500. So I am thinking there is some fuel issues... maybe a injector colapsing?
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From: Lexington, NC
Last night when I went out for a drive, a buddy of mine went with me. I ran the car up to speed and made it cut out on me so he could hear what it was doing. I was listening as close as I could and watching the tac.
It almost sounds like it is leaning out! But usually when a motor is leaning out, it revs up high just before it dies. So I dont know.
Also the car for the past little bit has had some trouble starting sometimes. It will just turn over and try to light and sometimes it will fire up and immediately stall out. Then when I try again, it will light right up and run fine. I am wondering if there two things are connected?
Some one told me that the reason that the car wont start like that is due to a lazy oil pressure sending unit. When the computer is reading low pressure it will not alow spark. I thought about that some more later, and that makes absolutly no sense. If that was true, how would the car start after and oil change? When you fire a car up after an oil change there is no oil pressure for about 3 seconds, then you hear a click and the pressure gauge jumps up.
It almost sounds like it is leaning out! But usually when a motor is leaning out, it revs up high just before it dies. So I dont know.
Also the car for the past little bit has had some trouble starting sometimes. It will just turn over and try to light and sometimes it will fire up and immediately stall out. Then when I try again, it will light right up and run fine. I am wondering if there two things are connected?
Some one told me that the reason that the car wont start like that is due to a lazy oil pressure sending unit. When the computer is reading low pressure it will not alow spark. I thought about that some more later, and that makes absolutly no sense. If that was true, how would the car start after and oil change? When you fire a car up after an oil change there is no oil pressure for about 3 seconds, then you hear a click and the pressure gauge jumps up.
Originally Posted by bmccrary
Some one told me that the reason that the car wont start like that is due to a lazy oil pressure sending unit. When the computer is reading low pressure it will not alow spark. I thought about that some more later, and that makes absolutly no sense.
If you think it's leaning out, hook up a scan tool and check the fuel trims and O2 readings.
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From: Lexington, NC
Originally Posted by dhdenney
Is it just me or does it sound like this guy's dad jumping in here? Haha, I figured out my dad seems to enjoy it when my car has problems. Well the post is now gone but whoever it was was talking about how you should be studying and "we should talk about insurance rates." But personally, my dad gets a kick out of me working on my car all the time.
