Hi- 5.0 1986 cougar. It surges while idling. it kinda goes away after warming up a little. but when i turn the lights on it is extremely pr0nounced. to the point where it is on the verge of stalling. but it hasn't stalled yet. any thoughts?
My first thought was a faulty throttle position sensor, but it sounds like the alternator may be on its way out.
pull codes,,
tps x 2
but still, pull codes for sure.
Paper clip = code puller
see diy link below
Turning the lights on puts more load on the engine. It makes the alternator harder to turn.
Surging could be a vacuum leak.
But do pull codes as suggested.
thanks everyone. it's uncanny to have so much help available. i think i'm going to invest in a scan tool....... i plan on keeping this cougar forever. Forgive me for not yet being adept at searching yet, but once i pull the code and cross reference the code to what the code means, is there a source that suggests how to trouble shoot that code? for example- CODE XYZ- "first clean abc sensor, then check make sure the curent is .999 jigawatts, if not then get a new sensor."
the reason i ask is so i don't wear out my welcome here by creating a thread for every single little problem I encounter!!!!
Don't get a scanner just use the paper clip method. That's what I do. It's easy and most of all free vs the ~$40 for a code scanner.