Idle problem 1991 automactic

[happydays1951]

Hey you all, First time on this site, and really looking for some help.I have an 1991 atuomactic owned since new.194,000 miles and still going strong.No oil usage at all...Have not done any marjor work to this car,regular maintenance and such...I have just had it tuned and new injectors installed. Before the tune I had this miss at idle, to the point that the car would stall out at a stop.The mechanic that did the work told me that he has checked every code,nothing shows up and he has looked at the wiring as maybe a source of the problem. He was good enough to not charge me any labor since he could not fix the "stall" at the time he did the work. Does anyone have a thought on this problem.One comment made was that it could be a bad valve or maybe wear on the cam staft(194,000 miles).Where should I turn next? I really do not want to open this engine if I do not have to...As I said I have had no major problems at all besides the rough idle and stalling.... HELP !!!!!!!!!!!!!!! Thanks All, Rick

 

[92ghost]

Your throttle Body (TB) may need to be cleaned, and/or your Throttle Position Sensor (TPS) may need adjusting. I don't think either of these will throw a code. 196K is a testament to how well built these engines are.

 

[Hib Halverson]

194,000 miles....misses at idle with the engine tuned properly and with new injectors.

The person who suggested a burned exhaust valve or a camshaft going flat has offered some good advice.

I'd run a compression check looking for a burned valve, first.

 

[jsinga]

You can get compression test done now days without even pulling out the plugs with the right test equipment. They disconnect the ingition system and watch the current draw pulses on the starter. It doesn't show psi but it does show a relative value.
It could be igintion, some HEI rotors will short across the screws, also distributor cap.
You can have a lot of problems that won't set a code. It needs a scan tool to look at stuff.
I think stalling sounds like the Idle Air Control isn't working right anyway. Also there is a minimun idle adjustment that should keep the rpm at least 500 in gear.
I have a 210K mile 87 and it's still going and hasn't been opened up.

JS

 

[8388]

Is it a constant miss, or eratic idle ? If it can't hold idle, then more than likely it's the IAC motor located at the throttle body. also make sure you don't have any vacuum leaks.