Quick Question
 

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Do you by chance have a water pump leak? Coolant and opti's dont go well together and it somehow manages to get inside an opti thats not brand new. Other than that, I would say check yer pigtail to the opti. Check fuel pressure is adequate, might have a pressure regulator issue under load. Other possibility is a clogged cat. See if you got good exhaust flow while someone revs the engine, after its hot of course since thats when yer having issues.

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Have you checked for a faulty ignition switch?

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It looks like you ignored a lot what the trouble codes were telling you. There was no need to replace every sensor and some of those other things. I don't see where you refer to spark plug wires or plugs. That would be the first place to go with multiple misfires. You should also have looked into changing the O2 sensors. The code for the AIR system is a common one and is usually just a blown fuse.

Clear all your codes and when the trouble returns, scan again to see what comes back.

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a faulty ignition switch wouldnt allow the car to turn over would it? the security light isnt staying on. it comes on when u turn the car on but when u go to crank it, it turns but wont start. so im not thinkin its a switch issue....am i wrong?

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When I asked the question about the ignition switch, you had not made us aware that it cranks when you turn the key. You indicate the car shut off and would not start. My question was based on the limited info you supplied. You left us with the impression it was an intermittent problem.

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yeah that was my fault. it will turn over but not crank. im kinda stumped. considering everything ive replaced. i just dont know....

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Turn over and crank really mean the same thing (to most people).

Two basic questions...does it have good fuel pressure (assuming it has good fuel) and is it getting spark to the plugs?

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when u turn the switch on. the fuel pump pulls up and when u press the shrader valve it shoots gas on the inside of the hood. first thing i checked when it quit running. getting spark to the plugs.....not sure about. i work alot so i have very little time to work on it. i was gonna use a digital multimeter to check connections but honestly...i have no idea on how to use one. ive got one that reads AC and DC, but i dont know anything about the settings on it or how to use them.

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The correct way to check the fuel pump is to measure the pressure with a gauge. The pump primes ("pulls up"??) but will not continue to operate unless the PCM provides the signal to the fuel pump relay. The PCM will not do that if there is a problem with the theft deterrant system, or a problem with the low resolution pulse signal from the Opti. If there is a code for the IC Module, the PCM will not activate the injectors. Presence of fuel peeing out the Schrader vavle does not confirm the engine is getting fuel.

The codes for the Opti and the ICM typically do not turn on the SES light. Might be worth scanning for codes again.

You can check for spark by pulling a wire off a plug and holding it near the block to see if there is a spark.

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+1 need to check spark, and i might add since our wires are so hard to get to, u can just check right from the coil wire first. If u have spark from coil to opti, then try a plug wire itself to see it spark making out the opti. Question, where did you get the opti from and was it new or reman?

If yer security light stays on its an issue with the VATS. I was unclear of your response that it comes on when you cycle the key. If not operating properly it will crank, but not start. Does it come on and stay on, or go out? Listen to what were telling you, u got some of the best lt1 experts here trying to help you, but if you dont listen we cant help you.

Oh, and ive yet to see an lt1 jump timing. Ive put 400+ hp through a used timing set many times. Not to say it couldnt happen, but ive never seen it.

Basic engine driveability, you need fuel, compression, and a correctly timed spark. These engines like to pop head gaskets, but usually you are aware this has happened when u start overheating. Assuming you have compression and this is not the case, first thing I would do is check for spark. If you have spark, id spray some starting fluid in the intake through a vacuum port (MAF must be hooked up to intake tube to run). If it runs, you know its a fuel issue.

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ill use the gauge on it. but like i said. the car wont run. so im not sure how i would get a steady reading on the guage.

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ill check the wires and let ya know how that went. i bought the opti online. it was suppost to be new. the security light goes off after a few seconds when u cycle the key. ive tried spraying starter fluid in the intake. it wont even try to run. when the car tore up last year. i tried the starter fluid and it would run for a second and die. but this time. it doesnt do anything. so im assuming it is a firing problem.

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