93 Lt1. I hope someone has expertise with fuel issues. I replaced the Opti, water pump, coil, wires, plugs and the check engine light finally went out and the car ran fine. I even wound it up to 6K a couple of times in several gears, all was well. About ten miles into my drive the gas pedal felt strange like a dead spot or response delay. It got worse to the point of getting out the number for AAA but it never died. It does not sputter, cough, backfire or stumble, it just responds slowly. From a light at %50 throttle it picks up speed so slowly that horns start blowing. At about 3K RPM it takes off like nothing is wrong but labors less than that (all gears). I replaced the fuel filter but no change. I put a gauge on the shrader valve and it has 38 PSI at idle and jumps to 42 with any amount of throttle. I drove it with the gauge attached and it did exactly the same driving, even during lagging. What the hell is this? The only code is 12 which means nothing wrong.

 

If your fuel pressure is holding at 38-42, you have adequate pressure at the rail. It might be injectors, but not too likely. Sounds electrical, perhaps the Opti.

 

How old are the o2s? Is the cat plugged?

 

The sensors are factory from 93 but wouldn't it show that code if it was one of them? If this thing had a carb it would be a stuck float and/or needle valve. It surges and goes flat and surges again. I just removed the air intake tube from the Mass Air completely and it does all the same. I thought it might have a restriction from the filter. UGH

 

My o2s never showed a code. I would change the filter and bang the cats while under there.

 

I would test the output of the tps.

 

Check your TPS and your MAP sensor with a scanner, to make sure they are reading correctly. A 1993 does not have a MAF, it is a Speed density system and uses the MAP and TPS to control fueling along with the O2 sensor.

 

optispark problem.

when mine was bad, the car would t accelerate when hot under load.

if you had it in too high of a gear or even windload (at triple digit speeds), it was just like hitting a wall

 

I will throw in my 2cents. My problem was pretty close to yours, after the install of 24lb injectors from Jon it runs like a raped ape.

 

car fixed, new Opti was defective. 3K in unnecessary parts and labor, 3 months of horror.

 

sorry to hear about the problems happy you got it working.

which brand optispark is working for you?

 

Can I ask what brand of opti? We need to know which brands have the most problems.

 

I put in a Petris and so far so good now for the op's answer.

 

He found a NOS Delco to put in and all is well, thankfully. This was a nightmare and a real learning experience for an old wrench like me. What was eye opening was the lack of knowledge in the industry which boiled down to my car is too old for current devises and specs, but too new for old non-scanning type devises and mechanics. When I threw up the white flag and started taking the car to 'experts', my local garage said it was a computer issue and he knows squat. I then went to the Chevy dealer. They said take it away as it is too old for the scanners/computers there. They did recommend new MAF and TPS which wasted more of my money. FB's used the same distributor etc, but they refused to accept the car for all the same reasons. They told me there was a shop 20 miles away that only works on plastic cars, specializing in Super/Turbo charging. Those guys have some dandy C6's being upgraded but told me C4 is too old. In desperation I found "Corvette Paramedics" in Mount Holly about 60 miles farther. They re-checked everything and finally recommended changing my 'new' opti for a NOS. THAT WAS IT!
So six months, 3K, twenty years of anguish, 5 full days of my work, 5 different repair shops, and the loss of use for this entire summer. Now I have the unholy task of trying to get some compensation from Cardone who sold the defective "rebuilt Delco" opti that started all this. I hope I get a couple of days to enjoy the car before I have to put it back in hibernation for the winter.