Alright, car was back firing bad, i changed the mass air flow and the o2 sensor fixed everything... except now the car shuts out at about 4 grand at wide open throttle. i know there was just a post about this but my car is a 305 tpi. i replaced the throttle position sensor but it didn't help so now it's up to ya'll.
thanks,
Derrick

 

c'mon ya'll are my last hope

 

okay by no means am i an expert mechanic but this is the very simple process i use to figure out problems. You need 4 things for your engine to work air fuel spark and compression. Id be willing to bet the as far as air and compression your fine obviously replace your air filters if theyre dirty but that wont solve your problem. Now to deal with fuel and spark. Spark wise id think it could be a failing coil due to the fact its only at rpms. You can take it to a mechanics of sorts (not sure how they test it) and they can test your coil and see if its okay or not. If your getting spark air and compression that leaves fuel. Again if its rpm related i would think its a dieing fuel pump that cant keep up when the needs are high.

If its fuel you should notice your engine leaning out at higher rpms. If its not leaning out check the coil.

 

btw someone else should chime in here because there are a lot of things that can happen in fuel injected cars that make things less simple then my diagnosis thats just the best i can do.

 

i appreciate the reply i'm prob goin to go ahead and replace the ignition stuff b/c it's prob not been replaced since it was new(exept for the wires) if that doesnt help then i guess i'll see about a fuel pump.
thanks

 

np id get your coil tested even if youre going to replace it just because then youll know for sure thats what it was. Helps for diagnosing future problems.

 

Those are both very good possibilities, but the first thing that came to my mind was ignition module. Usually they just die all of a sudden, but when they do "ease out" they get unstable at high rpm's first. Then they get unstable at low rpm's, then one day the car just won't start. It's cheap and easy to change, and it's a common enough problem. That's where I'd start.

Also don't get a cheapy (i.e. GP Sorensen.) They don't last long. Go with the AC Delco if you can find one.

 

thanks i'll go with the ac delco

 

just for s&g let us know when you figure it out.

 

did you find it yet? how many miles are on the motor?

 

i havent yet. i go to work today, so i will be able to get it tonight(i work at advanced auto) the motor has 100,000 miles on it

 

Also, I would have someone reve it while you sit in the engine compartment checking out the spark. Disconnect a plug wire and hook it to a brand new spark plug and ground the threads. You must get a blue flame or you have problems. Could be that you are not getting a strong enough spark that gets blown out at higher RPMs