hi i have the random multi cylinder misfire code ,my car is getting terrable gas milege 10 mpg and this is basically a stock car it has edelbrock headers and slp loudmouth exhaust.,you can smell raw gas ,um it has a bad miss and it pops pretty bad,it seems to do pretty good at wot ,but just normal driving it runs like crap ,here is what ive done,replaced the opti spark with a new gm part,coil,coil wire,plugs,plug wires, also every now and then the car wont start you have to crank on it for like 10 sec then it stutters and finnally starts,(this has only happend 2 times,and it was after i had taken a short drive and cut it off ,then a few min later tryed to start it)um i figured if i was runnin this rich i would have alot of black smoke,but i dont have that much,i have a guy comming monday to hook a tech 2 up to it,do yall think this will tell me my problem? and also try to give me some ideas ,

 

O2 sensors and a plug wire problem is possible,your car goes into open loop at wot.

 

what is open loop?

 

In open loop your pcm ingnores all sensors and uses set programming for fuel and timing.I have had cars with bad wires run fine at higher speeds but off idle miss bad.I know you replaced them,might want to check and make sure they are all connected properly.

 

i have check my wired and they look right if i happen to have one wrong will the tech 2 tell me

 

I am not sure.does your car miss at idle? If so you could pull the wires one at a time till you find on that doesnt change the way it is running.

 

If you have someone with a Tech II coming to look at it, hopefully they will be knowledgeable enough to look at sensor readings while it is running and tell you what might be wrong. You might want to read Fred/Injuneer's write-up on sensors, readings and stuff.