When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hello I have a 1992 LT1 I bought last year with 34k. Car is all original except for tires. Ran great last year and took her out back in April after a long cold winter. Drove her 3 times and put maybe 200 miles on her and then back in May went out and got about a mile from my house and it started idling rough and backfiring. Backfiring only on acceleration but it's more like a pop then a backfire and doesn't happen all the time. Rough idle always though. I see a lot of posts on here about the opti spark problems with these. Was hoping for some advice what to check for before just going out and replacing the opti.
Thank you Jim.
This is where low miles means way less than High years. If the car is really all original, there are a lot of parts that are 26 years old.
All original is great if you plan to trailer it and show in preservation class, for a driver not so much.
I've had my 92 for about 18 months and have gone through most of the major stuff.
New opti, wires and plugs
New fuel pump, fuel filter, injectors
New water pump, heater core (was leaking) all new hoses, thermostat, radiator cap and radiator. TB bypass installed.
New rotors and pads
Tires were already new (less than a year per the date codes)
New weather stripping
New KYB Shocks (Bilstein fans throw rocks now)
All new fluids from front to back.
Hatch struts, found out it should fully open on it's own
One seat track, other one doesn't work but the passenger can deal with it.
This is where low miles means way less than High years. If the car is really all original, there are a lot of parts that are 26 years old.
All original is great if you plan to trailer it and show in preservation class, for a driver not so much.
I've had my 92 for about 18 months and have gone through most of the major stuff.
New opti, wires and plugs
New fuel pump, fuel filter, injectors
New water pump, heater core (was leaking) all new hoses, thermostat, radiator cap and radiator. TB bypass installed.
New rotors and pads
Tires were already new (less than a year per the date codes)
New weather stripping
New KYB Shocks (Bilstein fans throw rocks now)
All new fluids from front to back.
Hatch struts, found out it should fully open on it's own
One seat track, other one doesn't work but the passenger can deal with it.
You are absolutely right! Never thought of it that way. Wish I came to this site before I bought it. I thought by getting something with low mileage and I paid top price for it, that I would have better luck then buying one with a lot of miles. I guess I will just start replacing parts slowly and start with the basic maintenance stuff first. Again thank you for opening my eyes.
Fuel filter could be full of junk. Also feel the coil wire. Bend it slightly between your fingers. If it feels "crispy" under the insulation, time to replace it, the cap & rotor, and the plug wires. I must have replaced the coil wire five times in the 15 years I owned my 96 impala. Probably replaced the cap & rotor 3 times.
You are absolutely right! Never thought of it that way. Wish I came to this site before I bought it. I thought by getting something with low mileage and I paid top price for it, that I would have better luck then buying one with a lot of miles. I guess I will just start replacing parts slowly and start with the basic maintenance stuff first. Again thank you for opening my eyes.
Hope I didn't discourage you. I did all the work myself and spent around $1500 for everything listed. Plus I know a lot more about my car.
JMO, but the first purchases you need to make are a factory service manual. Available on CD or paper. If you have a laptop get an ALDL cable and download tuner pro. With those two items and the help of the people here you can work through most any problem.
Since you have a 92 you can pull maintenance codes through the Speedometer display. Might tell us what's causing your problem.
Hope I didn't discourage you. I did all the work myself and spent around $1500 for everything listed. Plus I know a lot more about my car.
JMO, but the first purchases you need to make are a factory service manual. Available on CD or paper. If you have a laptop get an ALDL cable and download tuner pro. With those two items and the help of the people here you can work through most any problem.
Since you have a 92 you can pull maintenance codes through the Speedometer display. Might tell us what's causing your problem.
BelarieBrian is spot on; low miles does not always mean better condition, Often it means "swap everything."
However, do not throw money at your car. You will go blind trying to fix problems that don't exist.
You lean condition (as stated above) is most likely fuel starvation. My suggestion is to "fix it the right way":
1) test your pressure on the schrader valve. If you don't see at least 40, then...
2) swap the fuel filter. If you don't see 40 on the test, then...
3) Pull the fuel pump and check the strainer. Clean if necessary and bench test the pump.
First thing to check and it won't cost a dime.....injector resistance. If your running ethanol fuel its only a matter of time before the original multec injectors fail....not if...when. If your vette is all original thats where I'd place my bet.
Since the codes begin with H they aren't active
H=History
C= Current
Only one, the 33, is engine related it's a MAP sensor fault, but again not current.
You drove 200 miles in April, so you either left the gas tank near empty, either could have introduced water into the system. So you may want to try one of the water encapsulators on the market.
Did you wash the engine?
Anything might be a clue.
If car is back firing it is the opti. At the same time removing opti change water pump.. Components do not fail because of mileage its the heat generated by the motor hood being closed. . Open hood if possible every time you stop,also do not drive thru deep puddles or wash engine this gets water into your opti (distrubutot) and corrodes the cap and pits the rotor over timeAlso strive for a new water pump because the design is poor and you need every edge to keep your car running when you need it The gas filter is paper and running your fuel to reserve scavanges fuel and will plug the filter in your tank (Fuel pump) and under neath the passengers fender on a 92-96 model .
Since the codes begin with H they aren't active
H=History
C= Current
Only one, the 33, is engine related it's a MAP sensor fault, but again not current.
You drove 200 miles in April, so you either left the gas tank near empty, either could have introduced water into the system. So you may want to try one of the water encapsulators on the market.
Did you wash the engine?
Anything might be a clue.
I drove the car 3 times in April Each time about 75 miles and each time topped off the tank with 93 before going home. The last time before this started I wanted to see what kind of ***** this car had so I went up the street about a mile and turned off my asr and smooked the tires a little :-) brought it home and the next time I went out I got about 2 miles from my house and that's when the misfire and backfire started happening. Could something have come loose ? Ive checked the best I could all connections and all seem fine. I did notice yesterday one injector is not vibrating when you touch it. Not sure if that means anything? I'm not mechanical at all. Also it is running rougher now.
I drove the car 3 times in April Each time about 75 miles and each time topped off the tank with 93 before going home. The last time before this started I wanted to see what kind of ***** this car had so I went up the street about a mile and turned off my asr and smooked the tires a little :-) brought it home and the next time I went out I got about 2 miles from my house and that's when the misfire and backfire started happening. Could something have come loose ? Ive checked the best I could all connections and all seem fine. I did notice yesterday one injector is not vibrating when you touch it. Not sure if that means anything? I'm not mechanical at all. Also it is running rougher now.
If you can check the resistance of each injector. They can fail other ways, but sometimes the windings in the coil can open and the injector stop working.
I drove the car 3 times in April Each time about 75 miles and each time topped off the tank with 93 before going home. The last time before this started I wanted to see what kind of ***** this car had so I went up the street about a mile and turned off my asr and smooked the tires a little :-) brought it home and the next time I went out I got about 2 miles from my house and that's when the misfire and backfire started happening. Could something have come loose ? Ive checked the best I could all connections and all seem fine. I did notice yesterday one injector is not vibrating when you touch it. Not sure if that means anything? I'm not mechanical at all. Also it is running rougher now.
So it is the optispark. Does anyone have any suggestions on where to buy the parts?
Please help misfire backfire
Pull the codes if there are any.
