Well a couple years ago my water pump sprung a big leak, car started misfiring really bad, figured 90% chance it had to be the opti so I replaced it (and got a new waterpump)

Car ran excellent for about 3 weeks, then it started to misfire again. Took it to a shop, told them to fix it as I was frustrated. They said they found a small leak from one of the hoses (darn hose clamps!) They put a new clamp on, but didn't fix the issue. (Wanted me to take it to a different shop, they didn't do much work on fuel injected cars)

I decided to then just park the car and deal with it next year. Couple years go by and I finally get the urge to get the car running again. I figured with that small leak, and 3 weeks with a new opti, that it HAD to be the opti so I got a new one (delphi one from thepartsladi $300.

Well, I replaced the opti, and it is still not running perfect. Idle seems fine, it revs up good, still lots of power. NO misfires if I'm heavy on the throttle. (Will do a 0-60 run with no misfires) It misfires when there's a heavy load and I'm light on the throttle (acceling in 2nd gear at the pace of traffic, just a couple misfires) If I stomp on the gas while going (Say going in 3rd gear at 2k rpm if I stomp on it it 'stumbles' for a half second then picks up)

6 out of 8 spark plugs were replaced when I did the opti, so they have 1000 miles on them. The two passenger rear plugs I couldn't get at and the ones I removed looked fine, so I left them. (I did them 4 years ago, maybe put on 20K miles) I did the wires about 30K ago, they are 9mm OTVC wires. Car is stock other then azizona speed and marine midlength and a borla exhaust. (No cats)

Fuel filter has 35K on it. Fuel pump has 15K on it.

Thanks!

 

Have you scanned it for codes? Have you checked the fuel pressure? Have you popped the hood in the dark to look for arcing wires? Have you checked the inlet elbow, to make sure its not torn, and not folded under on the bottom, and not on the throttle body?

 

It doesn't have a CEL so would there be codes? Have not checked fuel pressure yet, nor to look for arcing plug wires (not sure if I'd be able to see them, as it's only under load, perhaps the engine is twisting and touching a wire??)

Inlet elbow should be ok, it looks like it's sealed all the way around the throttle body. There is a small tear, but it shouldn't be leaking through it. (It's where the 'clamp' is.)

 

Yes, there are codes that do not turn on the SES light.

 

Took the car to a Corvette shop and they put it on a scanner. No codes, everything looked good on the scanner, ran it for a couple minutes. Went into closed loop, still nothing. The gentleman suggested I put some dialectic grease on all the spark plug boots, look for carbon buildup in any of them, and possibly replace a spark plug wire. (Said it looked a little burnt)

That sound good to everyone?

 

I can't see how anyone can sell a real Delphi Opti for that cheap.I just bought a new one for my 94 and it was $423.We buy about $250,000 worth of sheet metal a year from this G.M.dealer so he gave me a deal and also told me that was the price G.M. sells to him.I'm thinking bootleg.

 

I highly recommend running it in the dark and looking for arcing wires, particularly the coil wire. Mist some water in the area and look for little blue arcs going to your water pump or anything else metal. I've also had the same issue under the same circumstances in the past, and the coil wand ICM were faulty. Coils are a cheap replacement, unless you ruin the ICM by being too aggressive while drilling out the rivets that hold the stock coil in place (ask me how I know.) You could check fuel pressure too, but I think you'll find the answer in the wires, coil, and/or ICM.