Opti replacing time i think.

[95LT1Z28]

Ok, i was crusiing in the car the other day and it felt like it didnt have the power it usually did. So im driving and it just shut off completely, then would just crank and wouldnt fire. I guess its time to do the opti. Im torn between the GM performance one or the MSD. I want one that will last so i dont have to do this job again. Any info would be appreciated.

[Fixxer99TA]

What are your future plans?

[Tyler Wheat]

The GM optis are tried and true, not to mention they can support quite a bit of power. I haven't had any experience with the MSD, but there have been a couple of people claiming problems. Whether it was an install error or an actual manufacturing problem I don't know. I really don't think you can go wrong with either one.

[Z28pr0jekt]

check the icm first... when my cam swap was complete we let the car idle for about 25min.. all a sudden it just shut off

we thought it was the coil, replaced it and the car fired up, we shut it right off then went to start it again a few min later and it wouldn't fire.

Replaced the icm and coil and it's been fine ever since

[joelster]

Why do you think it's simply the opti? Did you do any diagnostics?

[fuels94]

check the icm first... when my cam swap was complete we let the car idle for about 25min.. all a sudden it just shut off

we thought it was the coil, replaced it and the car fired up, we shut it right off then went to start it again a few min later and it wouldn't fire.

Replaced the icm and coil and it's been fine ever since

I'm with z28projekt check out the icm. I had one do that sometimes the car would fire up, or sometimes it wouldn't turn over.

[95LT1Z28]

When I first got the car (only had for a month or two, it did the same thing to me while idling in my driveway, I replaced the coil and icm and it still would only fire sometimes and stay running. Then it was good for awhile, after putting about 50 miles on it this happened, so my next guess is the opti? or maybe the PCM? Or could i possibly have gotten a bad icm?

[Tyler Wheat]

How do the plugs and wires look?

[Blubird]

if you do end up having to replace the opti, i would go with the msd unit, i installed mine april of 07 and havent had any issues,it has better connecting points and is sealed better than any other opti out there, yeah it sucks its $500 bucks but its a damn good unit

[95LT1Z28]

Plugs I already replaced when i first got the car. The wires looks good. No rips or bear areas. I actually pulled a wire off on each side to se if i was getting spark and there was a little bit there, i tested it with a paperclip and the clip didnt even get warm, so the spark is hella weak. And Blubird, glad to hear the msd unit is working good for you, i dont mind spending more money on stuff that is a better all around product. Thanks so far guys, Anybody thinking maybe replacing the icm again? maybe i got a bad one? Or May the pcm be faulty?

[fuels94]

Plugs I already replaced when i first got the car. The wires looks good. No rips or bear areas. I actually pulled a wire off on each side to se if i was getting spark and there was a little bit there, i tested it with a paperclip and the clip didnt even get warm, so the spark is hella weak. And Blubird, glad to hear the msd unit is working good for you, i dont mind spending more money on stuff that is a better all around product. Thanks so far guys, Anybody thinking maybe replacing the icm again? maybe i got a bad one? Or May the pcm be faulty?

Do you still have the receipt? Some place part stores will give lifetime or up to a year warranty so it wouldnt hurt to double check the part if you can get a replacement for free.

[Tyler Wheat]

Have you done anything with the coil.? Its bound to be the coil or opti considering that's about all that's left to replace lol.

[95LT1Z28]

Well today, I re checked everything, still no start, but I pulled the coil plug from the dist. cap and tried to see if the spark would jump, and i didnt have anything. Now my guess either has to be the coil, ICM, or if those both check, could it possibly be the PCM. Would a way to check that be measuring voltage at the harness connectors for the coil and the ICM? What should the voltage readings be for these three connectors?

[kinglt1]

You can have the local parts store check the icm and coil! Autozone does it for free. BTW when you pulled the coil wire off the opti, did you stick a spark plug or screwdriver in the end of the wire and ground it to the block when you checked for spark?

[95LT1Z28]

I tested for the spark by oulling the wire off and holding it over the contact with the lights off and watching and listening for it.

[Tyler Wheat]

Put a spare plug you have got laying around in the wire just to make sure. It's alot easier

[95LT1Z28]

ok ill try that saturday. Thanks, If the coil and icm check good what should i invesigate next, power at the harness connectors for the coil and icm?

[Tyler Wheat]

ok ill try that saturday. Thanks, If the coil and icm check good what should i invesigate next, power at the harness connectors for the coil and icm?

If you have good spark to the cylinder, I'd start looking at fuel problems.

Check injector pulse
Check Fuel Pressure