I'm having problems with my iroc running it has the 5.7 tpi automatic trans. It runs good only on short drives on longer drives it will idle rough and act run rich and also have a power loss. Now these are the only codes that are being thrown by the ecm. With this being said would the oxygen sensor be bad or is there something else I should be looking at before I nickel and dime myself to death lol. Thanks to all that help

 

you should check your spark plugs for a lean condition first. white ashy looking deposits indicate a a lean condition.

 

I will do that asap. One more thing I noticed is while I'm driving at let's say 35 to 40 mph the engine sounds like it drops a cylinder or leans the fuel out. Now it does this when the car is at operating temp but before the car is at operating temp it runs liked a raped ape lol. But I t doesn't through a code right away it will do this a few minutes then throw codes. When the car sits and cools off I can start it right up and it runs like new then after its warm back to running like crap.

 

whats the back ground on this car. how many miles? all stock or are you running any mods? recent work done? last tune up?

 

The motor has about 130 to 140 thousand. Last tune up was less than 6 months ago. The only mods to the car are smog pump has been removed. I replaced the maf,fuel pump,cap rotor,and coil all within the last 6 months oh and the tps as well. I don't think I have the tps adjusted right but I'm not getting any codes for a tps problem.

 

it wont throw a code if its not properly adjusted. just wont run right. this might do it to because, i beleive a maladjusted tps wont cause an issue untill the ecm goes closed loop.

 

I think your right on about the tps. It seems that when the engine acts ups is when its warm but doesn't throw any codes. I believe a mis adjusted tps is messing up the o2 sensor after a longer drive and causing to read lean somehow.