no start issuse and is not making any sense
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Joined: Feb 2012
Posts: 26
I have a 91 z28 5.7 tune port, it has been bored and camed. Built for 1/4 mile, roll cage and all. Built from the ground up. Most parts on it are aftermarket proformance. It will not start under its own power. I can pray either in it and it will start and run, not for very long and does not run well. Does not sound like its missing thou. Just running rough and ideling up and down. It will not start without being eithered. Sounds like a fuel issue right......But its not. I have replaced the fuel pump, even thou it has had constant and correct fuel pressure. I also replaced the ignition control module, cap and rotor, coolant temp sensor, redone the intake gaskets and cleaned the injectors, and replaced the key and switch. I have noid lighted the injectors, I have tested the compression on one clyinder and it was good. It turnes over really good. The problem just don't make sense, seeing as it will start and run on either, but not on its own. I'm a diesel/auto mechanic so I have covered the basics, I.E fuses, battery, vats. Any advice would be great. I'm at a wall here........
check fuel pressure, should be about 45 psi. when its running, how is the power, fuel consumption, coolant temps? the hypertech chips are junk, mostly just an altered fuel curve or timing curve. try getting a stock ecm for the car and see how it runs, or get a custom chip burned from PCMforless if you know what the mods are. if can, check the timing as that will cause idle issues like you described. low fuel pressure or a lean condition can cause a bad idle, which will make it run warm and get good gas mileage
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