My 94 Z28 is running horribly and sometimes when at a stop w/ my foot on the break, it tries to take off on me. I took it in to a shop this morning and they hooked up their scanner and said that it has a knock retard of 15 degrees so it could be the knock sensor. I told him it thought it might be a bad misfire becasue at night you can see some arching under the hood. Ive already taken it to 2 different places and they both thought it was due to the plug wires and i had the wires changed at both places. The arching is still there and in the same spot so I am pretty sure its not the wires. The guy I took it to this morning wanted to still do the wires even though i told him i had hem done twice already and he wanted $500. I dont want to do the wires again because i am pretty sure its not the problem. Anyone know if the knock sensor would cause this? Is this something i can easily change in my garage or do i need a lift? Also, if I bought a datalogger would it be able to tell me the exact problem? I also told the guy I have hypertech programming installed and i suggested we remove it before he scanned the car but he said its not necessarry. Doesnt the programming affect the timing? Are there any other reasons beside the knock sensor that it would be 15 degrees retarded? Thanks for any help.

 

When the KS dies the PCM will retard timing 15 degrees till its replaced.

 

Good to hear. Im going to replace the KS and see if that takes care of the problem. As far as the arching, I dont think it will ever be fixed but even with the arching the car has ran great in the past. I wonder if maybe the wire going to the KS is arching? Although i dont think the serpentine belt is the shortest travel distance from the KS wire so I doubt it.

 

It will retard the timing, but the amount is continuously variable from 0-15*, depending on other sensor readings.

Exactly where are the wires arcing? Have you checked the plugs to insure the gap isn't so large that its forcing the wires to arc, even if they are brand new?

When you have your foot on the brake, do the RPM's surge upp and down, or is the idle always high?

 

I havent checked the plug gaps, i guess i just trusted the dealer to know it needed to be set and the car ran fine for a long time after they were replaced. Can the gap of the plugs move over time?

The arching is taking place between the metal piece the alternator mounts to and the serpentine belt. This seems very odd to me but maybe the belt has metal in it? My first thought was the wires so I ha a mechanic replace all of them but the arching was still there in the same spot.

When i am at a stop with my foot on the break, the idle surges up and down and I have to press the break very hard to keep the car from taking off. Yesterday while it was doing this, it actually died for the first time.

 

Depends what kind of plugs you have. Platinum, in theory wears very slowly, so they don't open up very much. Non-platinum may open up faster. The stock AC/Delco platinum plugs have a tendancy to lose the little platinum pucks, and that leaves a huge gap, that can result in the spark firing between wires rather than across the plug.

There are 4 plug wires wedged between the front accessory mount bracket and the power steering pump. A spark at that point will jump from the bracket to the closest conductor.

Now its starting to sound like an Opti problem.

 

When I talked to the mechanic on the phone he was thinking opti also but once he looked at it he said he doesnt think so anymore. Plus I already had it replace because it seems to be the most common problem with this car. I know the wires are right there and I was thinking that was the problem so I had the wires replace but it is still arching in the same spot. As for the plugs, Im not sure what brand they used but i imagine they are Delco since it was done at the dealer.

This is seeming hopless. Coutless trips to the dealer and a few performace shops and nobody knows. How many times should I let them replace my wires before I can rule them out. Its not exactly cheap to pay for the labor to do wires on an lt1 as im sure you know.

If after several performace shops and several trips to the dealer nobody can figure ou the problem, should i just cut my losses and get rid of it?

 

Everyone has an opinion. If it was my car i would get the wires that are run over the top if it continues. This should eliminate the arching in theory. The only problem is it would mean redoing them again which i know you don't really want to do. I would get the 8.5mm Msd ones and do it myself and save the money for something else. I would also put different plugs in and use a different brand. I thought the arching was caused by a bad plug wire with a break in the insulation or the gap in the plug being wrong. I would bet you can fix it this way but its your call and maybe someone else has a cheaper or faster idea. Getting the plug wires in a different location could help. I think you want certain ones apart and maybe there to close. Just guessing.

 

I'm tired of replacing wires and optisparks so i have decided to convert it to this system...http://www.delteq.com/

NO MORE OPTISPARK!!!

Get it back tomorrow, crossing my fingers.

 

Experienced "driveway mechanics" should be able to install the basic system in an hour, plus the time required to run the new plug wires.

Sounds great and good luck. Be sure to respond back with your results.

 

You're tired of throwing parts at the problem, so you...throw more parts at the problem.

 

Yes, more parts, but hopefully better parts. By doing this, I believe I am eliminating all of the possible causes for the misfire/arching/stumbling.

Took forever to get the parts in but hopefully will still be done today. Will post results soon.

 

I think you made a great choice. It costs a little more but how can it not solve your problem. How much did you pay?

 

Doesn't it say you must correct current problems with your opti before you can install the delteq system?

 

The arcing from the belt is not ignition related, IMO. Arcing from the wires to the alt bracket would jump to the nearest conductor, true, but that is the engine block it's bolted to. You would not see it. Belts can build up a static charge in dry conditions, like a Vaqn De Graf generator, and discharge to nearby conductors. I suspect static discharge. Wires might be a wild goose.