Quazz

iTrader: (1)

Hello all... I searched but didnt find much on this.


I noticed on the way home from work today that my 94 Z was misfiring under load. I got all the way home without issue, but I couldnt find anything wrong. At this point, it did not have a SES light lit.

I drive it around today, and noticed it was severely lacking in power, and was still misfiring. I noticed the #6 plug wire up against one of the tubes on the Pacesetter headers, so I ziptied it up and out of the way. It did not appear to be melted though. This did not change how it ran, however.

During one of my test drives, all of a sudden the SES light lit and the car immediately ran better. I shut down the car, and restarted it immediately and the SES was still lit. I let the car cool off, started it, and the misfire was back and the SES was off. After 5 minutes of driving around at low speed, it lit again and the miss seemed to dissapear again.

BTW, the SES light is STEADY after it lights, it is not flashing.

The car has had the following done recently:

Brand new Opti
Plugs
Wires
grounds checked and cleaned

It had a misfire problem shortly before I bought it, and it turned out that the opti was the culprit. I kind of doubt that two weeks after it was swapped, it failed again ( I know its not unheard of, but its not likely)

I tried to check codes, but because its a 94, it wont flash with the terminals jumped, and both types of scan tools at Oriellys will not connect to the computer when initialized. I know I could by a Moates Port to USB adapter and run Tunerpro to read the codes, or I could just go to a dealership I guess.

The plug wire that was up against the header was not melted hardly at all, it maybe took off the first thin grey layer on the spot it was touching. Is that enough to make it misfire? I started it up tonight in the dark and didnt see any arcing at all.

I appreciate any help, I'm pretty new to LT1's and GM as a whole (I'm a ford guy) but im a quick learner!

An NO, the opti did not get wet, I didnt go through a car wash, and I didnt pressure wash the engine bay. I know thats a big No-No.

Gojira94

iTrader: (4)

Try replacing that #6 wire with a spare and unhook the battery for a few minutes to clear the code and see how it does. Ultra low-tech, no cost first step...

Quazz

iTrader: (1)

My only issue with that is the fact that after it runs for a while, the SES light comes on and it runs without a miss. That seems like the PCM is taking a sensor that is malfunctioning out of the loop....Ill try it though!