i just bought an 85 t/a and it has an idleing issue every once in a while . sometimes it will fire up and idle nice and smooth at about 600 rpms and sometimes it will start up and idle like it has a huge cm in it and it will be a dog off of idle. could this be timing or some kind of sensor ??thanks

 

I would check the 02 sensor and adjust the TPS. Is it a TPI car or an LG4?

 

its a TPI and the on sensor is brand new i will start messin with the TPS also when it is idling rough the rpms are at like 3 or 400 rpms could the idle need adjusted? i know how to drill out that little cap i did it on my 92 firebird

 

sounds IAC related to me, possibly all carboned up and sticking in the bore

 

so what should i do take the throttle body off and scrape it out. someone also told me it sound like an injector going bad.

 

No, you can leave the TB on, if you remove the IAC get some Valvoline Syn cleaner and spray it up in the bore and into the little passage ihe pintle seats in. Also spray the IAC if it appears to be carboned up. The valvoline cleaner eats carbon like candy and leaves no residue.

It could be a bad injector, but to pinpoint it you'd need to either do an injector balance check or, when the engine is running rough and idling low like you describe, remove one injector connector from the engine and see if it gets worse, when you get to one that doesn't make it wirse or shut off the car, mark it as bad and keep going until all the injectors have been done. mark all injectors that don't make the engine worse or shut it off.

 

thanks alot ill try that tomorrow morning but any other suggestions are welcom just incase this isnt what it is