Hi, I have a 1997 trans am with an lt1. i bracket race the car on a regular basis. last year my electric water pump to a crap, and i had to install a new one. The car seemed perfectly fine after replacing it, but the times the vehicle was turning started to fall. by the start of this season the car was a half a second off what it ran before changing the pump. At the end of the season i went to pull the car off the trailer, and it seemed like it was misfiring at first then went away. i warmed the car up, teched it in, started it numurous times without the problem. when i went to do a burn out it felt like the car was laking power. i staged the car, brought the rpm's up, when i went wide open throttle the car bogged severly, and misfired the whole way down the track. Since then it has set a dtc for a random multiple cyclinder misfire, and will not run right even at idle. does anyone think that this is the opti failing, or do i have bigger problem?

 

is the check motor lite on?

 

good old opti spark

check compression for cyls?
do you get spark?

www.shobox.com is great for diagnosing problems

 

Multiple misfires:
Opti
coil module
coil
lean fuel mixture, check fuel pressure & pressure regulator
MAF dirty or damaged
Also check the O2 sensors with a scanner. Even though the PCM ignores the O2 sensors at WOT, it still uses the fuel maps that were updated during part throttle operation using information from bad O2 sensors.

 

yes, check engine light is on. Also pulled spark plugs and checked wires. the wires were fine, but the plugs were black from running rich. changed plugs but still same problem.

 

If you think it is running rich, check the O2 sesnsors and the fuel pressure regulator.

 

checked fuel pressure. It was fine. Did a compression test, it turned up nothing. finally i just took the opti apart. when did the cap and rotor looked fine, but when i took the rotor off to inspect the optical parts; it was full of rust and and had some radiator fuild in it. I think that i am going to replace the opti, the coil, and the o2 sensors just to be safe since it seemed to be running so rich for so long.