2006 STS V8 1SF RWD
My '95 STS idles pretty rough in any gear, it ranges from 650 rpm to 1000. The interior lights and headlights both dim when the rpms drop or raise, what's up with my car?
ISC = Idle Speed Control. Earlier models used an ISC motor that extended a plunger to contact and push on the throttle lever to set idle speed. Later models use an ISC valve that meters the amount of air that bypasses the throttle plate to control idle speed.Azriel said:Hello,
Forgive my ignorance, but what is an ISC motor? Never heard of that, and don't know what ISC stands for or controls. Just curious to learn more.
Could it also be a vacuum issue that's causing unstable revs?
Please don't be so quick to wager your life on what might only be a loose battery cable.CadillacETC1997 said:. . . . Id bet my life its the battery
Ranger said:Not sure if the '95 uses an ISC valve or motor but if it's the latter, that may be the problem if the previous items don't help. One way to tell if it is going bad is note if the ISC motor (if yours has one) ratchets after engine shutdown.
Only reason I mentioned plugs/wires is I put in new plugs at 107k and my idle noticibly smoothed out. I did not get any misfire codes, they won't set unless you have a pretty bad misfire. This was just a slight miss. My plugs were between .065 and .070, with one around .075 when I pulled them.Eldyfig said:So, did you get all that? Let's see what has been tossed your way:
Plugs/wires.....if your plugs were bad enough to make the rpms fluctuate that much, you would be getting a misfire code. However, if a coil pack was starting to go out, you wouldn't get a code with OBD1.