I have been having some trouble with my 93 z28 lately. Some other post i have done will show more info,.. so ll try to make this short . I just cleaned my throttle body out. Took it off and cleaned it with valvoline carb and throttle body cleaner. I also cleaned the IACV with it. It says its safe for o2 sensors and CATS so i thought that it might be ok. I forgot to take my TPS sensor off... i know dumb *** me. Anyways i put it all back together after i cleaned it all and it started up ,idling fine for a minute then i revved it up and then it came back down to idle at 1500rpm . Restarted it a couple of times and still the same. Now it wont start. ? My other question is since IACV is different on the 1993 models and i dont have to re tighten the spring down or anything . Could i have just killed the IACV ? or even the TPS sensor while i was cleaning it ?

 

The IAC is delicate; you might have damaged it during the cleaning. If it is fully closed this would likely cause the engine to die. I also found that the TB blades can "hang" and not close all the way after cleaning. This isn't the source of your no start condition but likely why your RPM's wouldn't drop below 1,500 RPM. I dabbed a small amount of oil of the rod that the blades mount to where the rod enters the housing. This solved by sticking blade issue.

 

one more vote for the IAC. it could have been stuck open after lceaning, raising your idle, then it just shut completely, and now your engine wont start. try keeping your foot ever so slightly on the gas when starting the car, and see if that works.

 

ok will try thanks for ideas guys

 

Scan it for codes.... you may have a problem with the TPS.