LT1 down on power and backfiring
03-20-2012, 07:30 PM
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LT1 down on power and backfiring Hi guys,
So I just bought a 1994 formula that was sitting for a couple months. It wasn't starting because it wasnt getting any spark, however, once I disconnected the MSD 6A box from it and just went back to the regular wiring it fired right up. I've left the box unplugged, however the car feels really sluggish and at around 2-3k rpms there are some isolated backfires. Another thing pertaining to the sluggish thing once it gets to around 3k rpm it is really slow to accelerate past that. In neutral you can rev it to 5k but actually driving it I haven't found a road that is long enough to get it to anything past 3.5k rpm. Do you think the problem pertains to the msd box not being plugged in (the guy said it was tuned for all the mods he had on it)? Let me know your thoughts. Thanks
So I just bought a 1994 formula that was sitting for a couple months. It wasn't starting because it wasnt getting any spark, however, once I disconnected the MSD 6A box from it and just went back to the regular wiring it fired right up. I've left the box unplugged, however the car feels really sluggish and at around 2-3k rpms there are some isolated backfires. Another thing pertaining to the sluggish thing once it gets to around 3k rpm it is really slow to accelerate past that. In neutral you can rev it to 5k but actually driving it I haven't found a road that is long enough to get it to anything past 3.5k rpm. Do you think the problem pertains to the msd box not being plugged in (the guy said it was tuned for all the mods he had on it)? Let me know your thoughts. Thanks
03-21-2012, 03:54 PM
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An MSD box is not required for a LT1 to run properly...I would leave it disconnected since it seems to be causing issues and is of no real performance gain unless boost or nitrous is involved. Sounds like somebody unloaded their "problem car" on you. Start by checking the fuel pressure....maybe the fuel pump is on it's way out? If that checks out, turn your attention to ignition components....LT1's are fairly problematic in these areas 
Wires, plugs, opti, coil and....IGNITION CONTROL MODULE....this little POS can act up causing random starting issues....I know all too well because mine kept dying randomly last week. It was the 3rd one I've replaced since owning the car 
Wires, plugs, opti, coil and....IGNITION CONTROL MODULE....this little POS can act up causing random starting issues....I know all too well because mine kept dying randomly last week. It was the 3rd one I've replaced since owning the car
03-21-2012, 08:10 PM
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Well I went and got a fuel pressure kit from my local auto parts store, and on a cold start, turning the key to the on possition the pump pressured the system to about 15psi...I turned the key off and then on again and it went upto ~32psi. When I started the car the pressure went to ~35 but fell down to 32 again. reving the car the pressure goes down by ~1 or 2 psi but comes back up again quickly. I then taped the guage to my window and went for a ride at WOT. The pressure jumped to ~40 or something in that range (couldnt really tell as it was taped at a weird angle) but it seems to be working normally right? Perhaps the fuel filter could use to be changed?
Or should I move on to ignition stuff? Thank you for the reply
Or should I move on to ignition stuff? Thank you for the reply
