I just bought this can and did the mods in sig because the car had been sitting with a blow head gasket. This is my first LT1!! After putting the motor together it fired right up. I did not have a tune for it yet but i watched it on datalog with stock tune and drove it with open headders to get the exaust put on and it started mising and acted like it was loading up befor i got to the muffler shop. After i got the exaust put on it was still doing the same thing put it cleared up after 1 or 2 mins. It was lean a WOT and rich at cruise so i drove it easy back to the house. The car ran fine on stock tune so a few days later i drove it to a friends house to get it painted and it was fine did not mis or any thing. I left it there and he has only pulled it in and out 4 or 5 time and it was fine. Saturday he when to pull it out of the shop and it was mising and it would go died if he did not give it some gas. Sunday it went to pull it out and it would not start not even hit at all so i went over to check it out and it would not even hit. I checked the spark and it has a good spark so i got the 30lbs injectors and put them in and loaded the mad tune and still the same thing so i changed it back to stock with 30lbs injectors. and still nothing so i checked fuel pressure and it has 41lbs so it good but still want even hit a lick .... Can anyone tell me what i need to check. I would not think it would the the opit spark sence i and getting a good spark.. The only code it had was a (42 EST Grounded) i reset the codes but the only code i was getting when i tuned it over was the 42

 

Bad ignition control module. I had a similar problem with mine about 2 years ago.. I was out driving around with some of my friends, and when I went to take off from a light, blam, fell on its face and started to run like total crap.

It only got worse.

Happend not to long after I changed my opti, so I pulled it back out like 3 times in one day trying to figure out what was wrong.

Tossed my buddies snap-on scan tool on and got the same code. Replaced the ICM and I was off the trailor and cruise'n in minutes.

 

If the ICM is bad would i still be getting a spark when i stick a screw drive in the wire?? i did not pull the plug to check?? The ICM the thing the coil is mounted to and bolted to the head?? Like i said my first LT1

 

I changed my ignition control module and the car still will not crank?? Could it be the opti spark?? It still not hitting one lick and it getting fuel and when i check yesterday it was getting a spark...

 

Its been a while but I know on the older MPFI cars if you touched the gas when they started hard it would flood the plugs pretty bad and you would have to replace them. If you have spark at the wires and fuel in the cylilnders it should run. I would take some flammable carb cleaner and spray it in the TB whiel cranking to see if it fires. That would tell you if fuel is hitting the cylinders (unless of course you pulled the plugs and there soaked) check for good spark at the plugs.

 

I did pull a plug to day and they was a little gas on them and i could smell gas. The plug was black but i know yesterday it was getting fire at the wire but i did not check today..

 

Plugs may be fouled. Try holding the accelerator to the floor while cranking. The computer will go into "clear flood mode" and cease injector pulses. This may allow any excess fuel to be cleared out. It may help as FI cars can be a real booger to get going after they have been flooded.

 

Thanks SHOEBOX that what i tried after i made the last post. I pulled a plug laid it on ground and there was no spark the plug only had about 50 miles on them. I had a extra set of plugs (NGK TR6 4177) so i got one of them and laid it on ground turned it over and i had spark.. So i changed 5 plugs the ones i could get from the top (jacks broke) then i tuned it over and it fired right up still missing because of the 3 bad plugs i could not change from the top... Thanks for the help!!!!!!!!!!!!!!!!!!!

 

Yah just like the older MPFI cars if you touch the gas while cranking it shoots in a big bunch of fuel and fouls them beyond being useable. Happens alot up here in the cold winters of Maine. Older people pumping there FI cars to get them to start.