Idle performance?

[QUICK STORM]

changed plugs, cap, rotor, ATR black beauty wires, fuel pump, fuel filter, fpr. the truck still stumbles and idles rough, with the a/c on or off. and it feels like theres is a flat spot around 1500rpm. going to install a o2 sensor, an IAC, and a serpentine belt which is sqeeking on start up next week. my thought is the timing is retarded and needs to be advanced, which i will check. do you guys think the the map sensor and tps should be replaced too! any thoughts or do you guys think i'm heading in the right direction. btw all parts are ac delco. thanks.

 

[Syclone Rob]

yesterday I replaced all my vacuum lines and I can't believe how well my truck idles... (currently using UR5IX plugs-which are working great also) Now my truck has just under 25k miles on it. Maybe look at vac lines?!?!

 

[0966Sy]

There was actually a recall on some of the early model Sy's Eproms becuase a a rough idle. They had an updated prom that fixed it. I dont know about the Ty's in 92 though. I would try replacing all the vacuum lines with proper rubber sized hose and zip ties. Also you may want to try the Taylor spiro pro's instead of the ATR's. You should not need to replace the TPS or IAC unless there values on DM are out of limits. 25-35 at idle on the IAC counts and the TPS should get 4.2-4.5 volts at WOT. You can test with a DVOM and probe the conectors at the TPS with just the key in the run position.

Try cleaning out all the carbon with the GM "top end cleaner" if it's got some serious miles on her. Good luck dont forget to replace the PCV valves with the proper ones.

 

[GM TURBO]

Or...you could run Datamaster.