Car Question on the old LT1 pos!!!

[FBDragon]

My 93 T/A just quit on me with no warning or anything, it was actually instantainious (sorry for the bad spelling) I was at a stop sign and when I let the cltuch out and got half through the street it just stopped. I towed it home and the first thing I checked was to see if it had spark, it didn't and the best I can guess is that it is the ICM unit. Now I limited on tools and I have diagnostic equipment, is there a way to check the ICM to see if it is bad or do I jave to go and get a new one and hope I'm right. Money is super tight for me right now (still fighting for my disability) so I can't afford to waste money if you know what I mean.

Any advice or answers would really be appreciated !!!!!!

[Plawranc]

Instantaneous   

And no idea...

but hold firm, CAP shall be along soon to bring forth the solution.

[TequilaChaser]

Heya FBdragon,

I had my 93 Z28 six speed do the same thing to me years back........ I too thought it might be something in the ignition..... and it was since these were  non distributor type v8's it was the ignition modules/coil packs that I had to have replaced...... back then in '97 it cost me around $600 to have the Chevrolet place do the repairs

good luck on your SSD and also on your T/A

hope this helps

TC

[AAJagerX]

Probably that stupid optispark distributor that was used on those.  It's known to cause that issue.  You have to remove the water pump and the crank pulley to replace it, but the good news is that the part isn't terribly expensive.  The problem is that it's a PITA to get to.

[CAP1]

My 93 T/A just quit on me with no warning or anything, it was actually instantainious (sorry for the bad spelling) I was at a stop sign and when I let the cltuch out and got half through the street it just stopped. I towed it home and the first thing I checked was to see if it had spark, it didn't and the best I can guess is that it is the ICM unit. Now I limited on tools and I have diagnostic equipment, is there a way to check the ICM to see if it is bad or do I jave to go and get a new one and hope I'm right. Money is super tight for me right now (still fighting for my disability) so I can't afford to waste money if you know what I mean.

Any advice or answers would really be appreciated !!!!!!

 doesn't that one have the dist. below/behind the waterpump? 9 out of 10 times what you described is that cap/rotor. if you replace them, do the waterpump too, since it comes off to do the job anyway. i can't remember for sure, but i think that system has an external coil don't forget to check spark between the coil and cap. got spark there, but not at the plugs, you're going digging to the cap. no spark from coil, then check ignition control module, and/or crank position sensors.

[AAJagerX]

doesn't that one have the dist. below/behind the waterpump? 9 out of 10 times what you described is that cap/rotor. if you replace them, do the waterpump too, since it comes off to do the job anyway. i can't remember for sure, but i think that system has an external coil don't forget to check spark between the coil and cap. got spark there, but not at the plugs, you're going digging to the cap. no spark from coil, then check ignition control module, and/or crank position sensors.

Yeah, it's that one...  They're prone to failure, as they're not really sealed at all.

[CAP1]

Yeah, it's that one...  They're prone to failure, as they're not really sealed at all.

 yep. i've seen a LOT of those waterpumps dribble coolant right onto the cap, which also works its way in there........and then things go pretty wrong from there.

[AAJagerX]

yep. i've seen a LOT of those waterpumps dribble coolant right onto the cap, which also works its way in there........and then things go pretty wrong from there.

Well, that's one positive...  He may have had a failing water pump too.

If I'm remembering right, you can get an aftermarket distributor that's mostly sealed and has a vent...

[CAP1]

Well, that's one positive...  He may have had a failing water pump too.

If I'm remembering right, you can get an aftermarket distributor that's mostly sealed and has a vent...

 you are remembering right. those pumps used to dribble through the seal on the rear side of the pump where the driveshaft sticks out. that's why even if it wasn't when i did those caps, i still sold the pump.....because they were like ford 3.8 head gaskets. if they weren't leaking now, they would be extremely soon.

[Captain Virgil Hilts]

The Opti-Spark is crap, and so is the water pump. Go find a place to get genuine Delco parts for the ignition since you're on a budget, and see if you can find a Sealed Power water pump.

If you didn't have budget limitations, I'd tell you to get the MSD stuff with Moroso wires and solve the whole problem once and for all.

[icepac]

I rebuilt a couple of optispark units recently and all had been filled with coolant.

There are at least two versions with one being "vented" which helps keep moisture from accumulating.

I've found that the mitsubishi optical sensor is pretty robust and is used in many a nissan, mitsubishi, and other japanese car for 20+ years without failing.

That said, the GM usage of the sensor puts it into harms way and it only takes a film of oil over the sensor to render it non-operational.

Most that have had water intrusion will also suffer bearing failure down the road.

A gm specific scantool or one that can read the datalist of pre-obdII GM ecus might be able to tell you whether it is having an issue with the either the high or low resolution outputs.

If the datalist shows no input of high or low resolution signal from the optispark unit, then it is probably bad but there is always the possibility that another sensor or a shorted or open wire in the car is compromising the optisparks ability to get a good signal out.

If the datalist shows both high and low resolution signals while cranking, you could have an issue with the ignition coil module which receives it's order to fire from pin B5 of the ecu...........or the coil itself.

[FBDragon]

yea guys, I've replaced the dam opti spark 3 times now. The waterpump is new. The main reason that I think it might be the ICM module is that when I had to replace the waterpump it had failed the day before on a trip  on the way back. I wasn't able to get a tow truck at 1am in the morning on a back road. So it was going 1 or 2 times down the road at a time and then letting it cool down over and over again. I pegged the temp needle a couple off times. After I replaced the waterpump shortly after that I started getting a miss, it was not a irratic miss but a steady one like a cylinder was down. I never got a service ingine soon light on and it didn't show up on the diagnostics. I think I cooked the ICM unit.   So any opinions on that I'd appreciate them, Thank You guys for everything!!!!

[AAJagerX]

May be the water pump shaft seal...  That would explain the multiple failures, even after replacing the pump.  If the shaft drive coupling is jacked, it'll fail again.  Did you replace the coupling as well?

Just a thought.

EDIT:  After more thought, I'd bet that's the issue.  It'd explain why you had to replace the distributor 3 times and are having issues again even after replacing the pump.  Anything else I'd think would throw a code that'd kick the check engine light.

CAP!!!  Your input pleez!

[Captain Virgil Hilts]

yea guys, I've replaced the dam opti spark 3 times now. The waterpump is new. The main reason that I think it might be the ICM module is that when I had to replace the waterpump it had failed the day before on a trip  on the way back. I wasn't able to get a tow truck at 1am in the morning on a back road. So it was going 1 or 2 times down the road at a time and then letting it cool down over and over again. I pegged the temp needle a couple off times. After I replaced the waterpump shortly after that I started getting a miss, it was not a irratic miss but a steady one like a cylinder was down. I never got a service ingine soon light on and it didn't show up on the diagnostics. I think I cooked the ICM unit.   So any opinions on that I'd appreciate them, Thank You guys for everything!!!!

Wait, you've had a steady miss, ever since you got it so hot it pegged the temp gauge?

[CAP1]

yea guys, I've replaced the dam opti spark 3 times now. The waterpump is new. The main reason that I think it might be the ICM module is that when I had to replace the waterpump it had failed the day before on a trip  on the way back.what had failed before the trip? the waterpump? I wasn't able to get a tow truck at 1am in the morning on a back road. So it was going 1 or 2 times down the road at a time and then letting it cool down over and over again. I pegged the temp needle a couple off times.ok. this changes the game. you overheated the engine? more than once? After I replaced the waterpump shortly after that I started getting a miss, it was not a irratic miss but a steady one like a cylinder was down.this sounds like you blew a head gasket. I never got a service ingine soon light on and it didn't show up on the diagnostics. I think I cooked the ICM unit.   So any opinions on that I'd appreciate them, Thank You guys for everything!!!!

sounds to me like you lost a head gasket. if your ignition control module took a dump, you would have either a total no-start condition, or you'd have a start/stall.
 if the cap/rotor are bad, you'd end up with either a steady miss, or a no-start. if a wire is bad, you'd end up with a steady miss on the cylinder of the bad wire.

 my problem, is that you're now saying you overheated the car several times. if that car came into my bay, and i knew it was overheated, the very first thing i'd be doing, is identifying the dead hole, pulling that plug, and checking the plug condition. while the plug's out, i'd check compression on that cylinder, and also do a leakdown on that cylinder with the radiator cap removed.