T/A-Bob

My T/A has just 58K miles on it and has had 3 opti's. Each time was a genuine GM/Delco, along with a genuine GM/Delco water pump. Each time the car ran much better after... for 2 or 3 years. Mechanic A did the first two and Mechanic B did the third one. I am unable to work on my car anymore.

The car is now running like crap... a major "miss" at any RPM including idle. I'm bringing it in for a diagnosis, and if it's the opti (AGAIN) I'm going to be a very unhappy camper.

Any advice here? Why so many opti failures? And if I need another new one, do I go with the MSD "vented" cap? (I did some searching on this board). Seems that a true conversion is a very big deal.

This episode may be the deal breaker as far as me keeping this car. I simply cannot afford to be replacing opti's every 2 - 3 years.

Thanks.

lymlyt96

I was having the same problems, within 40k miles of driving I had replaced 3 opti's before switching over to the msd billet one. It held up for about 5 years but just recently went out. Right now I'm running a cheap opti with a lifetime warranty until I get enough cash to do the conversion which seems to be the only way to have any peace of mind with the ignition system.

shoebox

What was the postmortem diagnosis of the failed optis?

T/A-Bob

Getting my memory in order here... my opti has been replaced twice, not 3 times.

The first opti (Opti #1, original with the car) was replaced to fix severe stumbling at lower revs. The mechanic replaced some oil seals on the front of the engine (wish I could remember exactly which) and installed Opti #2. I remember Opti #1 seemed to have oil, actually greasy dirt, on the outside but when I took it apart out of curiosity I don't remember oil being inside.

Opti #2 removed 90% of the stumbling... but after a couple of years it got harder and harder to start the car, and finally impossible to start it in cold weather. I brought the car to a different mechanic (first one moved away). This mechanic was kind enough to play with the car for more than a week trying different stuff. The thing that fixed it was a new Opti (#3) plus a new GM/Delco coil**...

With Opti #3 and the new coil the car ran great... best ever. Three weeks ago (very hot day), I pulled up to a red light and the idle quality went all to hell. I continued on my way - had no choice - with a heavy consistent mis-fire at pretty much all revs.

The car has sat since then. I've started it once or twice since then and it does start after a little cranking, and the idle is quite rough as before.

I don't know if it's the opti again or not, just trying to figure out what to do if it is.


** I put in an Accell factory-replacement coil somewhere during the life of Opti #1 for the stumbling. It seemed to help a little. That coil remained during the entire life of Opti #2.

The mechanic who put in Opti #3 questioned that non-factory coil immediately. When he put in Opti #3 he said that just replacing the coil -or- just replacing the Opti, did not fix the problem. He needed to replace both to make it work.

Injuneer

Has any of the Opti failures set a code? Have you been able to pin down what went wrong with the Opti - burnt rotor, carbon tracking, disintegrated rotor, rust buildup, optical module, bearing?

What you are describing are the symptoms that lead you or the mechanic to decide to replace the Opti. But what Shoebox is getting at, is what was wrong with the Opti? Why did it fail?

mrmint69

I hear opti's being changed more than almost any other part on the car. It is almost the most expensive part, so you would think other things would be checked and replaced first. Very few are taken apart and checked to see if they are bad. I really don't think gm opti's are dying as fast as they are replaced. Definately if soon down the road it needs replaced again and again. Installation error would be one that could cause them to fail before they should. Also a different cam and mods that raise the HP above stock.

T/A-Bob

Fred, Rob, thanks for responding. Unfortunately I don't have any solid post-mortem information. I can't say for sure what was physically wrong with either opti.

I know the first mechanic diagnosed an opti problem based on scoping the ignition and seeing something in the waveform(s) going to the spark plug wire(s) that he didn't like, when he blipped the throttle.

In all honesty I believe the second mechanic diagnosed it based on instinct and intuition.

I don't know if Opti #3 is in fact the problem, just worried that it is due to the past. The car runs just like one spark plug wire is broken/dead... but I don't know.

I'm hoping to be able to give my mechanic some useful information either when I bring the car in, or after he's looked it over. I know this is pretty vague... I mean, if Opti #3 is dead, is it better to go with GM/Delco or the MSD? ... or is it impossible to say, since we don't know exactly what has failed in the past... ??


EDIT: @mrmint69, I agree with what you're saying, but all I can tell you is that replacement of the opti made a very significant improvement both times.

T/A-Bob

Update...

Yup. Wire to #7 no good.

Opti is OK

Tokuzumi

Looks like you have your issue resolved.

If you have to change the opti again, you might want to look at converting to the 95+ opti. I have only changed the opti once on my car, and that was when I did a tune up (plugs, wires, opti). Not because it needed it. I have changed out a water pump that dumped coolant all over the opti, and it hasn't had any problems with moisture.

T/A-Bob

I did some research on this board before going in (so I had some ideas on hand, just in case) and I decided that a full 95+ conversion would be too expensive for me. However, that "somewhat vented" MSD cap for 93/94's looks like it might be a good compromise.

But right now, my opti is OK and I'm very happy about that.

bw_hunter

Hi Bob,
Long time no see....

Anyway, I did the conversion to 95+ opti, mostly to upgrade the timing set and run a later (larger diameter center hole) camshaft. The conversion, with all new parts, was pretty expensive. If it's venting you're after, I think there is a write up on a corvette site where they modified a non-vented OPTI. It was well written up and fully illustrated. I mention this simply because I'm as anti MSD as can be. I've never had an MSD product I liked and wouldn't go with their parts on anything I use. I forgot this and put an MSD coil on my 94....turned out to be junk as well.

Good luck!

T/A-Bob

Hi man!


Thanks for the info about MSD.

I'll be sending you over a PM a little bit later...

Injuneer

http://www.corvettefever.com/howto/16758/index.html

GREGG 97Z

Fwiw, I have never had a single problem with my original 14 year old, 63k mile opti. GM obviously realized there were problems with the non vented version which was why they changed the design. Most all of the posts I see about opti issues are with the older non vented style. I did install an MSD cap & rotor when I changed the cam 3k miles ago. I wasn't even having any issues with the opti, just figured I might not have the motor apart for a while, just did it to freshen things up.

T/A-Bob

Thanks. I'm going to have this on hand just in case there is a "next time."