Runs Great Until 5000RPM - Then Misfire
#16
ok. I did a rev with the clutch in, went right up to 6800 no problems, no misfire, nice and smooth. This is a decent indication that the ignition is up to the task (at least while not under a load, but I cant image that changes TO much for the ignition system). So no I am leaning a little close to fuel filter not being able to flow enough at that rpm under load.
But now i have other problems to chase, after that rev I lost all oil pressure. Started a thread in the LT1 section about that.
But now i have other problems to chase, after that rev I lost all oil pressure. Started a thread in the LT1 section about that.
yea when you got the throttle open it gets a lot more air in the cylinder and and more gas, then its compressed, that's more stuff making it hard for the spark to jump. more stuff resisting the transfer of electricity. I already have them gaped pretty small to try to save my opti and to prevent problems like this. its at .035"
if its harder to spark in the cylinder then it may find an easier path outside the combustion chamber.
if its harder to spark in the cylinder then it may find an easier path outside the combustion chamber.
#17
i have been out of the game a while. I am ASE certified, but I don't work in the field anymore. But I got to thinking about my schooling and I remember spraying ignition systems down with salt water trying to find a arc. We were instructed to load the engine (gas and brake with a automatic - for a short period of time, or on the dyno with a manual).
#18
i have been out of the game a while. I am ASE certified, but I don't work in the field anymore. But I got to thinking about my schooling and I remember spraying ignition systems down with salt water trying to find a arc. We were instructed to load the engine (gas and brake with a automatic - for a short period of time, or on the dyno with a manual).
cough...
well i can tell you from experience its your ignition system. Time to do opti, plugs wires and maybe a coil.
First check your coil see if its missing. spray the coil with some water and look for sparks coming off the boot. If you don't see any sparks that means that the wire boot is still nice there. I would say spray your opti too, but it would be dead for sure after that and you can barely see it. But either way that's your problem, the opti. While you're there might as well do plugs and wires. if you know what you are doing its a 1.5 hour job.
First check your coil see if its missing. spray the coil with some water and look for sparks coming off the boot. If you don't see any sparks that means that the wire boot is still nice there. I would say spray your opti too, but it would be dead for sure after that and you can barely see it. But either way that's your problem, the opti. While you're there might as well do plugs and wires. if you know what you are doing its a 1.5 hour job.
#19
#20
the wires all look good. I made sure the rout them out of the way of the exhaust when I put it all back together. I zip tied them all together, they are MSD wires I am unsure of the size. But being that its so easy to change them I think I will, and I will get the required brackets to run the wires above the exhaust from the valve covers.
#21
It ended up being excessive back pressure.. my exhaust was holding is back so much. I took my Y pipe off and ran open header and it revs perfectly to fuel cut off and fast to. I plan on installing my SLP loudmouth Tuesday and that should flow a lot better than the junk flowmaster setup I have on there now.
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Alex Barnes
LT1 Based Engine Tech
16
01-24-2015 10:21 PM