Alright, so lately I've replaced a few sensors (o2 sensors, IAT sensor, knock etc) and had a new tune from lt1pcmtuning.com put on. The car is running nearly perfect.

I just got everything ready for the races today, drag radials on the back, going to the shop to pull my sway bar, etc. I pull onto the last road, give it some revs, and feather the clutch out to a perfect street launch. Not even to the top of first gear and the car shuts off. No pop, hesitation, smoke, NOTHING. The car still has full power from the battery, turns over perfectly, etc. I check for spark, nothing from the spark plug wires and nothing from the coil. I check power to the coil, 3 wires, one wire is 2 volts, the others are 0. I'm advised to put a new ignition module on it. Nothing. I check power to the ignition module, no power at all. All the fuses and relays check out fine, all the connectors look to be connected, and I've tried resetting the ECU.


Any ideas? Anything I've missed, anything I need to double check? I really have no more ideas and I need some help guys, the car is on the side of the road!

 

sounds like theres some kind of resistance.

it looks like with a quick google search 12v power is supposed to be the pink wire. find that wire, and follow it. there is a source of resistance somewhere in the circuit.


heres a schematic i found.



look for any sources of resistance in the circuit. remember, this could also be a ground issue, so check the black wire at the module.

 

also, this is clearly not a component issue, so dont buy any more parts.

 

im gonna go out on a limb and say its the opti spark unit. i had a 96 impala ss with the lt1 do the same thing........after testing everything even the wiring it ended up being the optical sensor inside the distributor.............. it would be fine when it was cold but if you ran it once it got hot it would act up.........eventually it would be a constant issue... new sensor in place the car ran excellent

 

check for any low reference signal codes too i think its a p1332 or something

 

i wouldnt go out and buy an opti until you figure out why you're only getting 2v

 

Was it acting up when it got hot because the coolant started to drip on the opti?

BTW OP, have you got a chance to check fuel pressure?

 

I would remove the ICM from the passenger head and have it tested.

 

no it was completely dry. i pulled the distributor off after testing and checking everything......once i had the dist apart i had the key on and manually spun the distributor shaft which spun the reluctor wheel for the optical sensor to pick up the revolutions. nothing happened..... hooked up another unit. worked excellenct...... retested the optical sensor.. it was definitely no good.... problem solved..... repaird the vehicle...... customer was happy

 

Could it be the opti if it's not even getting power to the coil or ICM?

Also, it cranks up and shuts off at random times? I've been able to get it to run and idle for 15 minutes straight, no problems. Shut off by me, then cranks right back up. Other times it might run for 20 seconds before it shuts off itself, then won't crank back up... hot or cold.

 

yes it can. those are the exact same symptoms i had with the impala ss with the lt1

the pcm is not seeing a signal from the optispark so therefor it will not send a signal to the ignition module and wont allow the coil to do its thing either


the optispark send a signal to the pcm which send a signal to the ignition moduel then to the ignition coil

 

how about a check engine light or any dtc's???

 

No check engine lights, it was throwing 2 DTCs, low res fail and (I think the other one was...) MAT or MAL something (I can find out for sure, if neither of those sound familiar or if they both sound familiar)

 

the low res circuit fail... bingo.......dtc 16..... i beleive low resolution circuit malfunction which is the red/black wire from the pcm to the optical sensor in the distributor............

 

So it's an opti-fail situation? GREAT!

 

from what you described yes . and thats the same scenerio i had with the impala ss

 

optispark units arent that bad to replace.. if your goin to replace the unit while your in there would be a good time to do plug wires too...... the dtc should be a (16) let me know for sure what you have for codes tomorrow or something... but im pretty sure it an optispark unit failure

 

i would double check your ground wires for any resistance and make sure the have good contact also would be a good idea to check the wiring from the distributor to the pcm use a good digital volt meter check for high ohms readings shouldnt be any higher than .005-.008 if you see 1.000 or higher then fix the bad wire before you go any further

 

More about the money that I don't have to spend on a new unit.

it was definitely a #16, and the plug wires are new, luckily.

All the grounds on the motor look great, as I was having some other problems that made me check them. Just run a resistance check between the pin on the pcm harness clip to the opti, to check?

 

yes if the wiring is good from the pcm connector to the opti connector then id say youll need to replace the distributor..... napa sells em for 165.00 or so......