GREENC493

I have a 93 vette with 81000 miles. The original opti started cutting out and backfiring so I replaced it with and MSD unit and a set of their wires and new AC plugs. This set up ran ok for about 6 months and then the mileage dropped off about 3mpg. I read one of the treads to check for wire arcing by checking the wires in the dark and when I did this I noticed a blue glow around the coil and did notice the arcing on the wires. Contacted MSD and they sent a new set of wires which did the same. When I called back they asked about a ground;so, I attached two grounds to the frame rails and the heads with no change. Wondering if the problem was in the MSD wires, I installed a new set of ac wires and plugs arced a little at first and a couple of weeks later worsened. I have tried the plug gaps at .050 and .035, multiple wire sets, plugs and grounds. My next step would be to clean the plug treads on head side of any old anti seeze and try again. No codes and the plugs are clean when I pulled them.

GREENC493

OK so last night I spent about 3 hours on the passanger side pulling the plugs cleaning the threads on them (with wd40 which worked well) and reinstalling them finger tight and removing them again to clean the treads to try and remove anything on the treads that might prevent the plugs from grounding to the head. I also double check my routing of the wires and wrapped each wire with loom. I started the car and listed to it idle smooth until it warmed up a little. The wire loom seemed to work. I could not see any arcing from wire to wire: however, I did notice a random flicker at the spark plug boot. The blue glow around the coil was diffrent as well. One side had a constant glow and the other side would flicker (maybe with the random plug mis). I still have multiple spark jump from wire to wire on the driver side, so , I will have to work on that this weekend. Has anyone else had this problem?

jimg's'93

I had some major arching when I first bought mine, but that was fixed with new wires. Not too sure what's going on with yours, but you might want to post this in the Tech/Performance forum. Not a lot of people read this forum much.

GREENC493

Thanks for the reply, I am on my third set of wires and it is better after I covered all the wires with loom: however, I can still see random arc at the plug boots. I am going to try a new set under warranty.

larry00

Please continue to post results as this problem likely exists with many of our cars with aftermarket parts on them.

Many people recomend using goop to prevent plugs from welding themselves to aluminum heads but the factory did not to my knowledge.

You gave me the idea to look at mine in the dark as I have electrical gremlins in my Hot Rods Ign. that are interfering with my Opti's signal.

As I have yet to wire in the Accel Gen. 7 computer with the required computer friendly wire and silver connectors I could be wrong.

I hate electrical problems !
Check with your FSM and find your eng ground strap and try to clean both ends.Corvettes and grounds are a long standing problem !

GREENC493

I did trace the batt ground behind the engine to the block on the driver side and found another ground running from the flex plate cover over to the frame rail. I will have to pull the fender to check the connection under the batt: however the the ground on the block was clean. I am planning on putting the new wires tonight and if I get time, check the ground under the batt.

mitchcole

I had the arcing coming from one of the 90* boots on a set of Taylor wires. I went over to Napa and bought a straight boot (wrong color) and a new crimp end. It's not pretty - but it works great.

Straight boots are much longer and prevent the shorter pathway that can lead to an arc. It's amazing to see a stock ignition system draw an arc more than a half inch long!

GREENC493

Wierd, I can see spark jump wire to wire, wire to head or wire to dip stick. I just can't get it to jump the plug. I have tried several ac 41-906's and a set of denso's. The grounds have to be good if it jumps wire to head, it just hates the plugs. Even at a .035 gap same troubles.