lt1 cranks no start.
11-04-2012, 07:29 PM
#1
Staging Lane
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lt1 cranks no start. my car is a 96 firebird with a lt1 swap new opti, and coil. it backfires then just cranks. its seeing 40 psi fuel pressure. the spark is there just really weak. i tried 3 different used icms with the same result. it has the vats bypass module aswell. firing order has been triple checked. Its my first big project ive done so i am at this point totally lost. any ideas?
11-05-2012, 05:37 PM
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It sounds like you didnt line up the opti correctly maybe. Or you bought a bad egg.
Take off the opti and double check, you shouldnt have to force it in, it should slide on and have no space between the opti and timing cover. And check cam sprocket on the opti(whatever the technical term for that is), and look for any signs of the cam dowel sliding in the wrong spot.
Take off the opti and double check, you shouldnt have to force it in, it should slide on and have no space between the opti and timing cover. And check cam sprocket on the opti(whatever the technical term for that is), and look for any signs of the cam dowel sliding in the wrong spot.
11-05-2012, 06:01 PM
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When I installed it we used a sharpie to mark the gear and the weld on the dowel. Slid on no problem lining them up. But I can't really rule anything out at this point. Any other suggestions I could try first?
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11-07-2012, 11:05 AM
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How about a bad crank sensor? Or bad fuel pump? What's the psi at the rail? Try spraying half a can of starter fluid in the TB. Even with a weak spark, it should ignite the alternate fuel source. If the engine starts and then dies, (you know the crank sensor isn't an issue), it's then fuel or spark related.
11-08-2012, 07:15 AM
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CPS on 96-97 LT1s is just used for misfire detection.
It definatly sounds ignition related not fuel. Dont over look the basics bc im sure youve checked the wires a hundred times. Check and double check all grounds, ICM conn.,Coil and OPTI connectors. When I was testing my opti, It wouldnt spark or the injectors wouldnt pulse. But the one time i got them simultaniously it backfired something nasty out of my intake. Now I have a new opti coming in the mail.
It can be a number of things,get out your multi-meter and start testing
It definatly sounds ignition related not fuel. Dont over look the basics bc im sure youve checked the wires a hundred times. Check and double check all grounds, ICM conn.,Coil and OPTI connectors. When I was testing my opti, It wouldnt spark or the injectors wouldnt pulse. But the one time i got them simultaniously it backfired something nasty out of my intake. Now I have a new opti coming in the mail.
It can be a number of things,get out your multi-meter and start testing
11-10-2012, 05:49 PM
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so found out i didnt have the ground strap from the coil to the frame rail, fixed that then discovered i forgot to ground the battery to the block. still same results will scan it monday for codes.
11-11-2012, 02:17 AM
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yea... not having the motor properly grounded pretty much results in no spark... as well as a host of other head scratching issues.
