psd_bullitt

Here are the symptoms:
The check engine light occasionally came on and codes would say random misfire but after a while it would go off on its own and there wasn’t any noticeable misfire or power loss. It would stay off for long periods of time and I didn’t notice any issues. Well driving to work a week ago it came on again but I didn’t fret too much. On the way home however it started to Flash (I’ve never heard of a flashing check engine light) and I noticed loss of power. It was knocking and running a little rough. I was almost home so I just babied it a few miles but by the time I was home it was definitely missing on several cylinders and running rough. Only code is random misfire.

I’m guessing it is ignition related and probably the Optispark Distributor as it has fuel pressure and MAF is clean and voltage is normal.

I’m having it towed to Corvettes of Dallas to check it out for me. I hope it is something simple. A friend says it sounds like the distributor but COD will diagonose it completely. The tech recommends an MSD Distributer over the GM if it is actually bad. I’ve read so many different threads about the Opti that my brain is fried. The original GM part has lasted at least 12 years so I can’t fault them too badly though it is an obvious design flaw putting it directly below the water pump. My pump does not appear to be leaking though.

Anyway, I’ve done some comparison price shopping on the web and found many options: There are probably many others but these range from $250 to $600. Is a $600 Dynaspark or $469 MSD really that much better than a cheaper brand like Accell, Jegs, or Delphi???

Corvette Forum Store:
Delco 95-96 OPTI SPARK DISTRIBUTOR
Product Number:M-3694 Price: $399.00

Delphi 95-96 OPTI SPARK DISTRIBUTOR
Product Number:M-3857 Price: $269.95

Ecklers:
MSD Performance Distributor Assembly, LT1/LT4, 1995-1996
Item# 51875 Price: $469.99 ea.

Accel LT1 Ultra Optispark II Distributor
Item# 59125 - Price: $299.99

JEGS
LT1/LT4 Distributor w/Vented Pin Drive
Item# 555-40011 Price: $249.99

Dynaspark.net
Dynaspark Distributor Gen II
LT1/LT4/L99 - Price: $599.99



EDIT:
Good News / Bad News:

Good News is that it is not the Opti Spark.

Bad News is they said I have a bad fuel injector in Cylinder 7 that was stuck open and has filled it with fuel. They recommend a complete set of new injectors instead of just replacing the single bad one. Justification is they are all now ~13 years old so I might as well take care of all 8 injectors now. Accel injector set ~$360 plus labor. They say the 26lb injectors are more then adequate for my mods and that there is still room for some growth. If I wanted to upgrade to a heavier flow injector I'd need to get it retuned. Ultimately I would make more upgrades if I was keeping the car but for now I guess I'll just go with stock size.

They also recommend replacing all the Spark Plugs but the wires are fine.

Thanks for the input on Optisparks. I guess its good news that I get to spend a little less money the I thought!!!

grinditout

I have have had all three in my hand, I have a Dynaspark on my car.

STL94LT1

I would stick with the GM replacement opti. You can pick one up from "thepartslady" on ebay for $245. I've seen too many problems with aftermarket units.

http://cgi.ebay.com/ebaymotors/95-96...Q5fAccessories

Normally when an opti is going bad it will throw a code. Since you have no codes present, I would check the crank position sensor first.

FYI: Don't drive a car far that is displaying a flashing SES. It could cause some serious damage to the engine or cats. A steady SES light is fine to drive on, it is just an emissions code.


-Mike

Redeasysport

Stay away from Accel haven't read too much good about them. IMHO the order of quality is
1.Dynaspark
2.MSD
3.OEM

That being said on your year you already have the improved opti and there is nothing wrong with it. Have your wrench put a good seal of "The Right Stuff" around the cap and put a hose on the WP (which you should change with the opti anyway) and you should be good for a loooong time.By the way Delphi and Delco are the same OEM units Dephi is newer manufacturing date.As stated thepartsladi sells OEM units. The Dynaspark is superior to the rest because it comes totally sealed with bearings(instead of OEM bushings) for the rotor and riveted rotor to prevent the rotor from coming off. The MSD is similar but you have to install the rotor with screws and put the cap on yourself. There have been reported issues with MSD rotors falling off possibly by bad install.

Kinkajou

I replaced my optisapark with an OEM from the partslady, but it failed at about 200 miles.
Rotor exploded. I thought that OEM was enough and I could save some bucks.
Wrong decision. I then used other system, can not remember the name but used a coil per cylinder. They had great customer service but did not work with my 94.

So I did what was needed in the first place. I got a Dynaspark. It has been the best money spent in my vette, it works great and is really waterproof.
It is a great investment considering the peace of mind it gives.

And by the way I saved a lot of bucks learning to change the opti myself wich would be a good option for everybody.

Good luck!

M. Schumacher

I narrowed down a similar problem to one cylinder by driving around with a code puller connected. Mine would get progressively worse as it warmed up. By reading the code immediately upon the light coming on I consistently got a cylinder six misfire instead of random misfire. It was a bad spark plug.

MikeC4

Regarding the OEM, that seems unusual that the rotor would explode after only 200 miles. Do you run at sustained high RPM's ??

BrianCunningham

You might get by with just a cap & rotor.
I did mine at 110k, I've got 140k on it now.

Dismantle it and have a look.

So far so good on my stock rotor & cap keeping together at the track.
Stock rev limiter setting though.

I bought an MSD for the new engine.

If you choose to buy one, take the cap off and put some locktight on the rotor, some have been loosing thier rotor at the track.

Good call on the weep line.
I'm going back to a mechanical WP, I've got an electric on it now.

pr0zac

tpiparts.net sells them cheap. i would do a gm or dynaspark. too much hear-say with the other brands for me to go with them. haven't really had a problem with gm ones that i haven't messed up from my own stupidity.

psd_bullitt

Good News / Bad News:

Good News is that it is not the Opti Spark.

Bad News is they said I have a bad fuel injector in Cylinder 7 that was stuck open and has filled it with fuel. They recommend a complete set of new injectors instead of just replacing the single bad one. Justification is they are all now ~13 years old so I might as well take care of all 8 injectors now. Accel injector set ~$360 plus labor. They say the 26lb injectors are more then adequate for my mods and that there is still room for some growth. If I wanted to upgrade to a heavier flow injector I'd need to get it retuned. Ultimately I would make more upgrades if I was keeping the car but for now I guess I'll just go with stock size.

They also recommend replacing all the Spark Plugs but the wires are fine.

Thanks for the input on Optisparks. I guess its good news that I get to spend a little less money the I thought!!!

Redeasysport

Get the Bosch IIIs or what he suggests from John at FIC he is a forum Vendor. See his sticky at the top of the tech section. I would stay away from the Accel injectors nothing but bad about them.

psd_bullitt

I called John and checked out his website.
His site has a great price. They are rebuilt but have a 3 year warrentee. He said the OEM injectors are not rated for the ethanol in gasoline these days so they start leaking and fail.
http://fuelinjectorconnection.com/sh...&productId=167

John confirmed that the LT4 needs 26lb injectors just like Corvettes of Dallas told me. According to the GrandSport Registry website the stock ones are 28lb for an LT4. It says LT1s have 24lb. I guess I'll ask Hutch at GSR what the deal is on that.

Thanks for the lead to this sticky thread for injectors:
http://forums.corvetteforum.com/c4-t...questions.html

.

onedef92

I'd go ahead and replace the wires, wire holders, and looms, too.

If you've got more than 60,000 miles on your car, there's no better time on and LTX engine to replace the ignition wires than now.

RoperC4

My water pump leaked all over my opti and it was an awesome time. Turned out all it did was solve problems I had been whining about on these forums for about a year with no conclusion.

I went with OEM unit I got off ebay for 100.00 (whole unit not just cap and rotor). And a new water pump obviously. I found a thread on here showing you how to use silicone and whatnot to seal the new unit better than it was from the factory. The reason I suggest and testify that is a good route to go is because I then sprang a seperate leak DIRECTLY over the opti again and it hosed it down pretty good and did not effect the opti whatsoever.

Good experience with stock unit replacement here.

RoperC4

PS: I agree its a dandy time to go ahead and do your wires, plugs, cleaning, etc.