cardo0

I see you got to the source of the problem. Congratulations on that and you have my sympathies for what it took to find it.
Good luck with the TorqHead 24x conversion and I hope you continue to post your experience with it.

Myself I will continue to struggle with Opti in my camaro. My current Opti is throwing code 36 - high resolution failure. So a new Cardone is going in soon. We will see if that can work. I also have a 12VDC aquarium pump and a 1 liter flow meter I'd like to try and convert to a positive pressure vented Opti - but that won't happen soon.

Good luck.

grandspt

I thank you! Don't get me wrong the original Optispark lasted 21 years and 41,000 miles so I am not too upset with it failing but I can't understand why the aftermarket cannot produce a quality replacement. And shame on GM for not manufacturing quality parts anymore, this is one reason why I will not buy another new GM product!
I talked to Paul at Torquehead on the 15th and he told me that he has been very busy trying to fill orders. He told me that he should be able to get the entire kit out to me before the end of next week. My car is down until then.
If he can't get it to me by then I will probably forego the Torqhead setup. Then I will be back reinstalling a new Optispark and take my chances.

grandspt

Looks like I am sticking with the Optispark setup. I purchased a Petris one from ZIP Corvettes. Wish me luck.

cardo0

Just FYI I'm going to try wrapping the Opti "pancake" all around the edge with self sealing tape - stuff used for radiator hose leaks and there are tapes made for electrical self sealing also.

Good luck.

1993C4LT1

Any update OP?

grandspt

Yes, sorry I have not updated my findings/repair. It has been a long diagnoses.
So the Perris Optispark cured my spark issues. Idle smoother, easier to get to redline. But I still had my hard starting, and my random misfiring. My short and long term fuel trims didn't look too bad. I then started to get a new different symptom which was pinging on heavy acceleration. It was very audible and could be felt. The computer was pulling timing. So after some octane booster which didn't help, removing spark plugs for the 3rd time and reading them (note Lucas octane booster turns spark plug electrodes and porcelain orange). I replaced the AC plugs to NGK Iridiums. Still pinging and missing!
I went back to the shop manual and rechecked my fuel system. The new Delphi fuel pump I bought from Napa Auto was bad. I had plenty of fuel pressure but when I turned the ignition key off my pressure dropped immediately. It would not hold pressure.
I removed the Delphi pump and purchased a new Deatchwerks (200) 255lph pump with a Holley Hydramat. The Hydramat was to eliminate a fuel starvation problem that this car has had since I bought it new. When the tank gets below half the car bogs when driven hard around a corner or even in a straight line.
The Deatchwerks pump is a very complete kit. There is one made just for the C4! It comes with the tank gasket, screws, thicker gauge wiring harness in the tank, filter sock (which I did not use because I used the Hydramat instead).
The car ran perfectly after the install!!
Instantly starts, idle is great , no more misfires and pinging. I can drive around corners aggressively with only one bar left showing up on the fuel gauge (something it never could do).
I am extremely happy with the outcome. The pump and Optispark were the issues for my problem. I think the Optispark contributed to part of the problem but the fuel pump made the biggest difference.
The Hydramat (although not related to my original symptoms) was expensive and a bit difficult to install. But was well worth the effort!

grandspt

Also the ICM I am using is the Borg Warner. All others throw codes. I bought two (spare).
I also left the larger heatsink for the ICM with my own harness connected. It keeps that ICM nice and cool.
I did leave the OEM one mounted on the cylinder head in tact but left it disconnected. This way if the ICM fails on my large heatsink I can just unplug the harness and connect the original ICM mounted on the cylinder head.

1993C4LT1

Very interesting on the fuel pump. Glad the car is running and pulling properly now
Bit off topic. But weren't you doing the torqhead swap a while back?

grandspt

Yes, I had it on order but I started to read about actual installs (which seemed easy and straight forward) and issues they had getting them running properly. Seems like there were some people with tuning issues, driveability issues, there was a YouTube video of a guy with an Impala SS that did a nice 3 or 4 part video. At the time he still had it at a tuner and never got it running right.
I didn't want to be a beta tester so I changed my mind and went with the Optispark.
In the future I may go the TorqueHead route. The owner seems like a real nice guy he answered all my questions and I think he has a nice setup. To me the replacement ECM that he modifies for the C4 Corvette might be an issue (just my opinion).

jayjones

This is one of 2 sticking points for me on the TorqueHead system. An LTx harness to LS computer adapter would be an easier sell than modified LS computer. Torquehead and EFI connection almost have an ideal conversion split between them:

• TH pros: can use existing harness, very nice packaging for manifold-mounted coils, bundled HPTuners, easy to install
  • TH cons: external reluctor, uses re-wired LS computer instead of off-the-shelf with adapter
• EFI pros: crank sensor built into timing cover, internal reluctor, can use standard LS computer
  • EFI cons: must use standalone wiring harness but don't offer one for Ybody, higher install difficulty

RichS

I finally got mine out to ECS to have it tuned with the new motor and Torquehead setup. Doug had no issues accessing and tuning the computer. The car is running great except for one issue. I have a "SYS" still for a code 81. I want to run the car and go to a few races, then Paul is going to look at things over the winter to try and resolve it. It made 442rwhp/560tq. Next test is the track where it really matters.