merlot566jka

Because the transformer movies sure would have sucked if optimus prime was stuck on the side of the road!

Past week I've had a missfire, or ignition breakup at WOT in higher rpm. I figured it was the plug wires from my header install. After rerouting the wires some I thought I had the problem licked.

Yesterday morning on my way to work, a spirited climb into the higher regions of the rpm band yielded some bucking and a serious misfire. I throttled back and shifted into second to realize that I had no power. I gave the accelerator a push, and the car died. I coasted to the side of the highway, and tried to restart. No luck. Being in the navy, I knew if I wasnt at work in 1 hour my *** was grass. Frantically I tried everything I could think of on the spot. Everything seemed to still be connected, no codes, fuel pump is whirring, and it sounded like I was getting a spark every few hundred rpms.
I came to the conclusion it was either the opti-spark or someone spiked my fuel.
I walked back home and got my M35A2 truck, which isnt registered and therefor not legal on the roads, and drove the 43 miles to work. The base police told me "no way" when I attempted to drive on base. So I parked at a marina and walked two miles to the ship.
After work I went back to the corvette and gave it a little better of a look. I have air, fuel, and spark. Yet the spark was weak and I obviously couldnt tell if it was firing on the correct cylinder or not. The fuel smelled clean and the cap was still locked.

The highway was too busy to push the car back home, so I called a wrecker and had her towed back to the house.

To add to the complexity of the situation, I am not able to leave the ship today due to the "fast cruise" and will be going out to sea for a week or so. So further diagnosis is going to be delayed.

The plug wires look old, and are the expensive MSDs

I cant see the opti-spark, but the water pump looks fairly new, indicating its age and possible tell-tale of the opti-spark's age.

The coil is an MSD and looks new.

The ICM looks about the age of the car.

The plugs are less than 1000 miles old and are NGK TR55's

I am fairly certain I have a dead opti-spark. What do you think?

-Jonathan Anderson

87 vette 81 big girl

Remove the #1 spark plug wire & set it next to the header tube or Exhaust manifold.

Or better yet with a spare spark plug, install it on the #1 spark plug wire.
Set the spark plug steel shell on the header tube likewise.

Crank the engine over & verify if you have a hot bright blue ignition spark present or not.

If not,
Need to troubleshoot the Opti ignition system further.

Running late for work.
Been there too.

merlot566jka

I did the arcing test with the boot pulled away from the electrode connector on the #3 plug wire. I saw I had spark, but it was weak.

radar502

I didn't see were you ran a scan . Need to do that the scan don't tell you it's the OPTI but will help ... I checked my 96 out for two days doing about the same thing..The GM OPTI SPARK was about 2.5 years old ..Hair line crack in cap.. Inside all green water just from the hair line crack... Have it scaned.. go from there..

merlot566jka

Scanned?
I have an obd2 code reader, I had no codes. Nothing stored as history either.

Unfortunatly only the optical side of an opti will generate a code. The hv side will not throw a code for a failure.

Now if you are referring to using an oscope to watch the spark signal from the opti... Then I have yet to do that. I am an advanced electronics tech in the navy, so I can grab one from work and give that a try, when I am back from being out to sea that is.

radar502

Sounds like a spark timeing thing or a short or a part going bad.. Can be just the wire comeing out of the OPTI.. I just work on mine and had good luck doing so...Lot's things to check Eng.module Ect. just keep asking and somebody has the answer . I always just start at the OPTI and work my way out I have the big book to look at and avery big stack of printouts and on and on...If you are going to trade it in I would just see how much it would cost to have it fixed and trade befor it went bad... It takes years to learn how to work on a C-4 ..I would let somebody fix it and move on you don't need the head pain ..Been working on them for 10 years takes a long time to get it right C-4s can be a pain.... Got to love it...

merlot566jka

I am not going to trade in, sell or get rid of my Corvette. I am also ASE certified, I have owned 3 C4's and I would never pay anyone to work on any vehicle of mine when I can do it myself. I can't get to the car to further diagnose it, which is why I am here asking if anyone thinks that sounds like a typical opti-spark death. I appreciate your help, though.

1963SS

That sounds like it could be a HV problem with the Opti. I have 300,000 miles on the original in my Impala and 150K on the original in the Vette. Both have been through water pump failures and engine washes. I have never had to baby them......maybe I'm just lucky. I have put the MSD cap and rotor on both. One had carbon tracking internally and the other I just did as a preventive measure. The one with carbon tracking still ran but it did have a bucking misfiring issue.

I'd find it hard to believe that there would be enough carbon tracking internally to just shut the whole thing down but anything's possible. The miss should have been evident for some time before it got bad enough to completely kill the engine.

Did this start just after the header install?

STL94LT1

I've had two opti failures, but no sudden deaths. Mine would cutout and die when the engine was hot, as soon as things cooled down it would restart and run like a champ.

radar502

OOOOPS..Sorry It's the heat I was reading another thread and got mixed up..The other guy was trading in his vett... Get to find out why lot's people stay away from the C-4s Opti thing.. Easy to check the igition module some shops set up to check lot's people just forget about them and they don't get changed out not cheep eather.. There is a wire that comes out of the Opti spark it plugs into the thing it can go bad.. A bad plug wire will not keep one from runing just miss ..It all goes back to the OPTI spark and the wires and moduls that support it.. .. If it was were you could get to it the first thing you would check would be pop the cap off spark thing to see if it was ok ..Not on this so the first thing we have to do is check all the other things that work off the Opti so we have to work back to the opti...If you are going to keep the ride dive in ..In the last five years I have changed three Opti Sparks on just two vetts a 95 and 96 one was 2.5 years old and all the stuff that that help make it work ..People who say I have 150,000 miles on my Opti Spark and look at you like your crazy there day is comeing.. I drive a vett with an Opti Spark I have AAA.. Best tool in the box...Good luck...

merlot566jka

Yes it started just after the header install. Never noticed it before that.

I am fairly certain this is the OEM opti, with 164,000 miles on it.

merlot566jka

Cause of failure found.

It was an MSD cap on an unknown Opti-spark. The rotor screws came undone and were fliping around inside of the optispark. The screws did not have any sort of loctite, and there is slight damage to the cap, more damage to the rotor than anything.

I tried another ICM just because I had it laying around and it was easier than pulling the opti. Turns out that caused a P1351, which is proving impossible to get rid of... something like 40 consecutive warmup cycles to get it to go away.... holy crap batman.

I am sure the old opti could be repaired with a new rotor, but I went ahead and replaced the whole thing with a CMS opti. The previous owner labled the plug wires on the opti end backwards for the drivers side. That was a huge mistake not to double check his work. Took an hour to take off the tensioner, pull the plug wires, trace them out and connect them properly. Also found #1 and #8 wires were missing thier metal band that aids the wire to connect to the opti. I used a drill bit that was just under the diameter of the opti connections, and inserted it into the metal clip and used pliers to make the clip opening the size of the drill bit. Then I filled the boot with dielectric grease and it snapped on fine. Seems to be holding up, but will replace all of the wires soon.

Just thought I would let everyone know what happened and how it was fixed.

Oh and CMS did raise their prices for a week, but they are back to where they were. He raised the prices due to low stock, but as soon as a shipment came in, he dropped the prices right back to where they were. I found out its best to contact him through his eBay store.

mfi

First thing i did when I replaced my opti was loctite the rotor screws..they weren't that tight....

ninetyfivevette

Yep, sounds like your rotor fell off. It has happened to me twice this summer..

mfi

I just don't understand why these things aren't loctited from the factory..or by who ever the hell puts them together..seems like a no brainer...

PLRX

why? because it is designed to fail for us to buy a new one before 100,000 if the car is poorly maintained.

Remember, the money maker is the sale of parts.

mfi

Yeah but these things are failing at 2K miles.....

merlot566jka

Cost, thats the reason its not done from the factory.

I used some procedures and tricks I have learned in the Navy to make sure those screws dont come out again. Its amazing to see how they assemble things for aircraft where FOD is a serious issue. Its a wonder they dont trickle down to the automotive world, could save millions of dollars in repairs.

helphos

Glad you found your problem. I replaced my Opti last week- what a pain!
Turns out the cap was full of carbon tracks. I replaced it with a new opti from Chandler. I probalbly could have save a few bucks by just replacin the cap, but oh well.
Anyway, it runs better than ever! And, oh, yeah, I did the loctite thing.
Good luck with your ride.