I have a 94 Vette, LTI, 6spd, w/35,000 mi on rebuilt engine, with new plugs, wires, cat, O2 sensors, and optispark. I drive 400 miles a week back and forth to work. This is my daily driver. I put in a OEM Optispark about every year, due to malfuntion. This year is a little different.

I travel approx 30 mi and I start to get misfire at about 2000 RPM or what it feels like when the Opti is going bad. I limp home not able to go over 2000 RPM. I lightly degrease and power spray the engine top and bottom, so it's clean to work on.

In the morning I start the car and drive and it feels like all is well. Why? Every other time the Opti went bad, it never got better, only worse.

I tested the coil anyway with a working test coil and drive for 2 days. and 100 mi with no sign of failure.
I switch back to original coil and drove for 2 days, and 50 mi with no failure. So I can't condemn the coil.

I then leave on my 200 mi trip home. 150 miles away, and the engine starts to cut out. I can't drive over 1600 RPM, and barely make it home.

If the car is off for 15 to 20 minutes the problem seems to clear up. Over night it is clearer but still stumbles from 1600 RPM up. Could some type of fluid be fouling the opti, intermittantly, then clearing up?

Question: Does this sound like the Optispark or has anyone seen this problem. I have seen a venting procedure for this year opti, anyone know if that works. Need help, I would like to get more than a year from the Optispark

 

That statement and Optispark should not be mentioned together
Opti has enough problems with water that naturally gets on it from day to day use ;
let alone Hi pressure water forced at it

Run this question over in C4 Tech section for better response

 

Don't wash the engine.

You sure it's gm optispark? Lots a fakes on eBay etc.

Opti should go at least 30-50k. Some go 100k?

 

If you keep good wires/plugs on the car and dont get the engine wet a delphi opti should easily go 100k miles. Check your vac lines to make sure you are getting a good vac on your opti and none of the hoses to/from are torn rotted etc. No way you should be replacing an opti every 30k.

If you can get it to start stumbling at home while idling or in your driveway try and diagnose it at that point. Check fuel pressure to see if its not getting low as the pump gets hot. Change fuel filter.


Check codes and also check the harness for the opti. I have seen some mild corrosion in the female ends of the harness that caused intermittent issues but they always resulted in a code for the low res circuit.

 

[QUOTE=Dr. Evil;1576192170]If you keep good wires/plugs on the car and dont get the engine wet a delphi opti should easily go 100k miles. Check your vac lines to make sure you are getting a good vac on your opti and none of the hoses to/from are torn rotted etc. No way you should be replacing an opti every 30k.


As an owner of a bunch of C4's that is not accurate at all. Very few Opti's EASILY Go 100,000 miles. Many die before 50,000.

I always had, good wires, plugs and never got my motor wet. A Forum search will show that many people replace Opti's well before 100,000 miles.

Is it a Delphi Unit? That is KEY. If you are buying "look alike parts" there lies your problem.
I know many people that change opti's several times because they bought cheap ones ($100) on ebay. They may look the same on the outside but internally they are much cheaper.

 

xlr8,
I've had a 4 or 5 opti equipped vehicles. All went to at least 100k except my 96 which lasted to 94k. In that case the rotor button came off at 6700rpms.
When I worked at the dealership it was rare that we saw a car come in with a bad GM opti under 100k miles on it unless it had gotten wet.
I'm just relaying my experiences and opinion. There are alot of owners here who do indeed have issues well before 100k but you and I do not know the true maint history and quality of parts used. YMMV

 

The earlier non vented ones have a much worse track record.
Just make sure you are buying a gm or quality opti, the cheap ones don't go the distance.

If you search forum, you will see the mileages when people are replacing opti. Doing certain things will kill it prematurely, washing motor, going through large puddles etc. Good luck

 

Thanks for the imput. Yes the Opti is OEM from GM dealer they seem to work. Also I was very careful washing the engine as I know it fouls the Opti. I work at Corvette Restoration AZ. but these C4's are a bit of a pain. My daily experience is mostly C1, C2 structural and F/glass panels, mostly complete frame offs.

The car sat all week. I started the car after my work week. And all seemed fine, except a hesitation barely noticeable at about 2000 RPM, the gauge lights fluctuated at the exact same time. also barely noticeable.
I will drop the waterpump and Opti this weekend and take them to the shop and do the venting modifications respectively. They need it anyway. I will check wiring at the coil. Also change the fuel filter.
I'll let you know after next weekend.

 

You put a new Opti every year?? Quit washing your engine.

 

We specifically list power washing and driving through deep water as possible failure events in our "save your optispark" thread. If you need one we sell units for around $100 with a good rep.

 

I just wanted to ask if you have ever seen an intermittent problem with an opti-spark. I thought they either worked or they didn't. I know about them causing a problem when wet, but after drying out can they be intermittent? Thanks

 

We had a buyer call us once and I suggested he let his unit dry out over a week and he followed up to thank us it was working fine. Its like a cell phone. You drop it in the toilet and if you try to make calls with it you're done for. But if you let it dry for a couple days sometimes you're OK.