Missing. idling rough, and pinging '95
Thread Starter
3rd Gear
Joined: Nov 2003
Posts: 3
Likes: 0
From: Orlando FL
Missing. idling rough, and pinging '95
My 95 LT1 (120,000 miles) started idling rough, missing, and pinging under acceleration. It seemed to run pretty good at higher RPM. I thought I had some bad gas so I drained the tank and refilled (my Ford truck liked the Vette fuel just fine).
Same problem. And no trouble codes in the computer. I checked for spark with an inductive timing light and found 2 cylinders had no spark, #'s 2 and 5, which are on opposite banks. I pulled the wires, ohmed them out, and found no problems.
It seems strange to lose 2 cylinders at once on a single coil ignition. I'm just hoping I don't have to mess with the that dreaded distributor.
Any thoughts?
Thanks.
Same problem. And no trouble codes in the computer. I checked for spark with an inductive timing light and found 2 cylinders had no spark, #'s 2 and 5, which are on opposite banks. I pulled the wires, ohmed them out, and found no problems.
It seems strange to lose 2 cylinders at once on a single coil ignition. I'm just hoping I don't have to mess with the that dreaded distributor.
Any thoughts?
Thanks.
Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
Well, the coil works fine for 6 out of the 8!! SO I think your coil is not the cause. Unfortunatley, sounds like it may be your Opti. Has your current Opti pushed your Vette around for all 120K miles?? If yes, that's a lot of miles for the high voltage components in your Opti, ie the cap and rotor...... 
Thread Starter
3rd Gear
Joined: Nov 2003
Posts: 3
Likes: 0
From: Orlando FL
Originally Posted by MikeC4
Well, the coil works fine for 6 out of the 8!! SO I think your coil is not the cause. Unfortunatley, sounds like it may be your Opti. Has your current Opti pushed your Vette around for all 120K miles?? If yes, that's a lot of miles for the high voltage components in your Opti, ie the cap and rotor......
Yes - it's all original. I replaced the water pump about 20,000 miles ago and should have checked the opti guts. I'm still curious of how spark for 2 cylinders dropped out together.
Thanks.
Thread Starter
3rd Gear
Joined: Nov 2003
Posts: 3
Likes: 0
From: Orlando FL
Originally Posted by MikeC4
Well, the coil works fine for 6 out of the 8!! SO I think your coil is not the cause. Unfortunatley, sounds like it may be your Opti. Has your current Opti pushed your Vette around for all 120K miles?? If yes, that's a lot of miles for the high voltage components in your Opti, ie the cap and rotor......
Yes - it's all original. I replaced the water pump about 20,000 miles ago and should have checked the opti guts. I'm still curious of how spark for 2 cylinders dropped out together.
Thanks.
Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
Originally Posted by blueskyfl
Yes - it's all original. I replaced the water pump about 20,000 miles ago and should have checked the opti guts. I'm still curious of how spark for 2 cylinders dropped out together.
Thanks.
Thanks.
Symptoms of failing Optispark:
* Car suddenly dies and won't restart
* Starts but immediately dies
* Extended cranking to start
* Rough idle
* Sputtering
* Backfiring
* Trouble reaching higher rpm
* Black smoke from exhaust
* Poor performance with car warmed up
* Weak plug wire spark
* Codes 16, 36, and 42 may be set
let's wait for others to chime in on this one.....
Thread Starter
3rd Gear
Joined: Nov 2003
Posts: 3
Likes: 0
From: Orlando FL
OK, I'm convinced its the opti. What will likely have to be replaced? New cover/rotor - or whole new unit? I guess I could start the car with the water pump off to check repairs, but I want to get it right the first time.
Thanks.
Thanks.
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Originally Posted by blueskyfl
OK, I'm convinced its the opti. What will likely have to be replaced? New cover/rotor - or whole new unit? I guess I could start the car with the water pump off to check repairs, but I want to get it right the first time.
Thanks.
Thanks.
At that many miles I would replace the complete unit. The optical wheels has many small windows cut into it to form the sensor ring. If any of these are fouled and or if the optical sensor itself is on the verge of going bad, you will regret having to do it all over again. The cap and rotor kit costs over 1/2 of what the complete unit costs.
Check out this site for the best prices:
www.samtaylor.com
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Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
Originally Posted by blueskyfl
OK, I'm convinced its the opti. What will likely have to be replaced? New cover/rotor - or whole new unit? I guess I could start the car with the water pump off to check repairs, but I want to get it right the first time.
Thanks.
Thanks.
http://www.houston-f-body.org/tech/optispark/
If you are so inclined to spend additional $$, the Dynaspark unit has significant improvements over stock unit.
http://www.dynotech-eng.com/dynaspark.htm
Good luck...
