Help! Same problem is back!
Thread Starter
Racer
Joined: Dec 2004
Posts: 429
Likes: 0
From: Midddleburg FL
Help! Same problem is back!
Three weeks ago I had my 95 in the shop because of a misfire. Cap and rotor change on the opti was the fix (we thought). He also changed plugs and plugwires since he had it all apart anyway. The car ran great when i got it back. 1100 miles later and the same problem is back. Is it possible that opti is bad and causing the cap or rotor to go bad? What else can cause this. Please give me ideas before it goes back to the shop. Thanks in advance.
Want to wish everyone a safe and Happy new Year!!!!
Want to wish everyone a safe and Happy new Year!!!!
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Check each plug wire with an ohmeter. They should be about 5000 ohms per foot and wiggle each end to make sure they aren't intermittent. I had new wires and one went open circuit after 2 days of driving. New doesn't guarantee good!
Thread Starter
Racer
Joined: Dec 2004
Posts: 429
Likes: 0
From: Midddleburg FL
Haven't got any codes yet, hoping to see one. Plugs and plugwires are without a doubt under warranty, and my wrench guarantees his work, so if that's the problem, no problem. How could the o2 sensors be the problem? Its only been about 3 weeks and 1100 miles since I got it back. Would the cap and rotor change "hide" the problem for that long? Once again, thanks for the input. I want to give my mechanic as much info as possible, so thanks for the response.
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Originally Posted by tm1995c4-LT1
Haven't got any codes yet, hoping to see one. Plugs and plugwires are without a doubt under warranty, and my wrench guarantees his work, so if that's the problem, no problem. How could the o2 sensors be the problem? Its only been about 3 weeks and 1100 miles since I got it back. Would the cap and rotor change "hide" the problem for that long? Once again, thanks for the input. I want to give my mechanic as much info as possible, so thanks for the response.
Changing the cap and rotor will not cure an optical sensor problem within the opti unit.
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
Right, but since everybody in the world swears up and down that it's the high voltage side of the opti that fails he probably didn't think to change that.
Just my $.02, take it for what you will....
If you think it's the opti, it's probably not.
If it is the opti, it is hardly ever the high voltage side unless your car has 100k plus on the original opti.
Just my $.02, take it for what you will....
If you think it's the opti, it's probably not.
If it is the opti, it is hardly ever the high voltage side unless your car has 100k plus on the original opti.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Opti 101:
The opti has 2 parts. High voltage and optical sensor.
If you are getting codes 16 and/or 36, then you have an optical problem, and the ONLY fix is a new unit.
If you are getting a problem with wandering idle or a high RPM miss, it's high voltage.
Other causations - if the unit has been exposed to lots of moisture, the internals of the cap and rotor will start to carbon trace at a rapid rate. This is what causes the wandering idle and high RPM miss.
Other things to check
1) The harness lead into the opti. They can become corroded.
2) The coil and ignition driver.
3) Coil wire.
The opti has 2 parts. High voltage and optical sensor.
If you are getting codes 16 and/or 36, then you have an optical problem, and the ONLY fix is a new unit.
If you are getting a problem with wandering idle or a high RPM miss, it's high voltage.
Other causations - if the unit has been exposed to lots of moisture, the internals of the cap and rotor will start to carbon trace at a rapid rate. This is what causes the wandering idle and high RPM miss.
Other things to check
1) The harness lead into the opti. They can become corroded.
2) The coil and ignition driver.
3) Coil wire.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Thread Starter
Racer
Joined: Dec 2004
Posts: 429
Likes: 0
From: Midddleburg FL
Thanks everybody for the input. Now I have a stupid question. Will I get a fault code without the check engine light coming on? Is it possible for the opti to cause the cap or rotor to fail/malfunction?
Thread Starter
Racer
Joined: Dec 2004
Posts: 429
Likes: 0
From: Midddleburg FL
Originally Posted by bogus
Opti 101:
The opti has 2 parts. High voltage and optical sensor.
If you are getting codes 16 and/or 36, then you have an optical problem, and the ONLY fix is a new unit.
If you are getting a problem with wandering idle or a high RPM miss, it's high voltage.
Other causations - if the unit has been exposed to lots of moisture, the internals of the cap and rotor will start to carbon trace at a rapid rate. This is what causes the wandering idle and high RPM miss.
Other things to check
1) The harness lead into the opti. They can become corroded.
2) The coil and ignition driver.
3) Coil wire.
The opti has 2 parts. High voltage and optical sensor.
If you are getting codes 16 and/or 36, then you have an optical problem, and the ONLY fix is a new unit.
If you are getting a problem with wandering idle or a high RPM miss, it's high voltage.
Other causations - if the unit has been exposed to lots of moisture, the internals of the cap and rotor will start to carbon trace at a rapid rate. This is what causes the wandering idle and high RPM miss.
Other things to check
1) The harness lead into the opti. They can become corroded.
2) The coil and ignition driver.
3) Coil wire.
The cars idles fine and at high rpm theres no problem. At idle when i rev the engine up between 1500 and 3000 RPMs is when it has the misfire. When the engine is cold it doesn't do it, but when the engine is warm it starts misfiring. When I'm driving at a normal speed and I start to accelerate to go 10-15 mph faster is when it occurs, light acceleration not enough to make the transmission downshift. The car has 117,000 mile on it and if I had to guess, I would say that this is the original opti. Thanks again for all the help.