I have an 87 Z-28/ 700r4 2800 stall/ with a rebuilt 5.7 TPI from a formula with about 20k on it. The problem I am having is the car runs rough, the warmer it gets the worst it runs. The car started out with a stall here and but ran strong and great then it would run good but if you took off fast it would bogg down and now its hard to start and it boggs and back-fires all the time. I bought a code reader and it showed MAF and TPS, replaced both and set TPS dead on. Car also has new plugs and I went ahead a replaced fuel filter after the problems started. Timing seems on and I can't find a vaccum leak. Any Ideals?

 

maybe IAC??

 

O yea! I unplugged the EGR valve and nothing in the idle changed. Maybe this is the problem????

 

Ok, like I said, yesterday I replaced the fuel filter and it still ran like crap, I checked again for vacuum leaks (intake etc...) and nothing. Today I check to see if any plugs backed out and none did so I started the car and was going to pull 1 wire at a time to see if I had a dead cylinder and try to go from there. Well I started the car and it ran great maybe a small hesitation when u stomp the gas but thats it. I took it out on the road and hit it a few times and no miss, no backfire etc. Then I put the code reader on it and its showing code 45 o2 sensor. Does this need replaced as well? everytime that damn code reader says I need a part I buy it and it don't seem to help. And does anyone have any idea why she is running good today even after heating up?

 

Just incase someone else is having this same trouble it was the distributor. Thanks all and goodluck.

 

wow thats wierd..i have almost the same problem...heres my deal..I have an 88 iroc and put a brand new 5.7 with the edelbrock set up, all of it was extrude honed..also a cam from comp!.Edelbrock headers and cat back system!! now the new motor has about 9000 miles on it!! just this past weekend its started feelin really sluggish!!..I would drive it and it would be fine for about a half an hour the all of a sudden loss of power..felt like it wasnt gettin any gas,or the tps wasnt reading right!! And same as u..also felt like the timing was way off!!!..so the distributor was faulty huh?? does this sound like what was happening with u??

 

Yea, thats what mine was doing, the ignition would get spark but i guess not enough at the right time. I thought it was timing as well. It would back fire and miss and all kinds of crazy stuff. I checked sensors etc...but when I pulled the cap off it was obvious. It hasnt run this good in forever. Goodluck.

 

good lookin out...i will definately see wus up with that!!...ill let u know if it was the problem!! thanks

 

well i figured it out!!!...it was the Mass Air Flow Sensor...finally!!!thanks for all the help!