New GM crate ls3 no spark from coils!!
Thread Starter
Joined: Dec 2009
Posts: 2,328
Likes: 29
From: Glennville, GA.
New GM crate ls3 no spark from coils!! Hey guys i got an issue with a customers ls3 2011 z06 vette. We ordered a brand new gm crate motor and installed it last week. Engine crank and ran perfect after 2 days of driving car shut off and hasnt started since! Turns over fine. Just no spark on either banks!
its been a minute since ive messed with a vette, but is there a rear head ground wire at the harness?? I installed the 2 on each sides of the block.
Here is what ive gone over and checked:
New maf since it was tuned maf only. Didnt work!
injectors are pulsing verified with noid light set.
im getting a reading for cam sensor counts.
im getting a reading for rpm around 250ish.
60psi fuel pressure.
Installed new battery with good voltage.
checked all underhood fuses and swapped around ign relay.
Checked accelerater and tb for response. Registered tps % on hptuners.
Im basicly leaning toward a bad ecu at this point. Or it could be a ground. But engine did run great when it was running. I checked coil harness and have 12v and ground. Basicly no signal from ecu. When we first got car running it did have a weak battery so we jumped it off and figured it would charge itself. Could the weak battery have fried ecu??
Also have 3 permanent codes stored.
P1682.
P2122
P2127
Any help would be appreciated. Thanks guys!
its been a minute since ive messed with a vette, but is there a rear head ground wire at the harness?? I installed the 2 on each sides of the block.
Here is what ive gone over and checked:
New maf since it was tuned maf only. Didnt work!
injectors are pulsing verified with noid light set.
im getting a reading for cam sensor counts.
im getting a reading for rpm around 250ish.
60psi fuel pressure.
Installed new battery with good voltage.
checked all underhood fuses and swapped around ign relay.
Checked accelerater and tb for response. Registered tps % on hptuners.
Im basicly leaning toward a bad ecu at this point. Or it could be a ground. But engine did run great when it was running. I checked coil harness and have 12v and ground. Basicly no signal from ecu. When we first got car running it did have a weak battery so we jumped it off and figured it would charge itself. Could the weak battery have fried ecu??
Also have 3 permanent codes stored.
P1682.
P2122
P2127
Any help would be appreciated. Thanks guys!
Last edited by brandon6.0; Jul 20, 2018 at 09:52 PM.
Thread Starter
Joined: Dec 2009
Posts: 2,328
Likes: 29
From: Glennville, GA.
Problem solved! Loose ground on driver side block. Some how bolt wasnt tight enough. Tightened it and car fired right up.
Codes are still present and want clear out, but car does run now. So well see what happins. Thanks guys!
Codes are still present and want clear out, but car does run now. So well see what happins. Thanks guys!
Thread Starter
Joined: Dec 2009
Posts: 2,328
Likes: 29
From: Glennville, GA.
lol well usually when I install an engine I make sure they are good and tight and usually wiggle the wire. Them corvettes are crammed and hard to get to places especially with headers and such. But good thing its running and customer is pretty happy!!
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I would have to double check, but usually an engine is grounded to the chassis in 3-4 locations. With the Corvette transaxle set-up, it might even be a few more. I would be double checking your other grounds as having 1 loose ground should not cut power to the whole ignition system. If that were truly the case, I would be running another wire from maybe where the engine mounts to the block to the frame.
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