i need help, my 86 cougar is idling a little rough, almost like the miming is too slow, but the manual says that the idle is controled electronicly and cannot be set. would a failing ignition coil cause this? i ask because it is also taking longer to start than normal. I was on my way to Neb. this weekend and it started cutting out and "bucking" I was afraid it was my transmission, but after stopping at a gas station, i barely got her started again. once i did i headed home, grabbed the ranger and took off again. Tonight, after i got back, i replaced the plugs, wires, rotor, cap, and fuel filter ( i have had issues with filters in the past, and it was due for a mini tune up anyway) It runs better, but i'm not happy with the idle, seems rough. any ideas?
well for starters the first thing you always wanna check with a bad idle is what controls the idle--the IAC, Idle Air Control, motor, which is attached to the side of your throttle body. Thats why "it cant be set". If its really dirty/gunky inside clean it out WELL, i think you should also lube the stuff you can see through the two holes with 3 in 1 oil or something (wait for more replies not sure on that but i thought somehwere somebody mentioned oiling it)
once youre sure the IAC is functioning right, then move onto other stuff.
good luck!
Mmmm...that's the big clue. I sense a failing fuel pump, as longer start times is usually one of the warning signs (and sometimes there are no signs at all, so maybe you got lucky). You could try cleaning the IAC and EGR, see if that helps.
The idle is controlled by the computer, generally. This depends upon readings from a few select sensors, like the IAC/idle bypass valve, the TPS, the EVP/EGR system, and the MAP/BPS sensor. If one or more of these sensors fail then the computer reverts to a set of predetermined values. That means the car will run and try to idle, but maybe not greatly so. Therefore you need to look to those sensors first. If everything is okay and they are within operating parameters then other things have to be considered: clogged converter, clogged charcoal cannister, or fuel pressure, things like that. You can have your fuel pressure tested, too...that would probably be a wise thing to do soon.
Run codes before you swap any more parts.
will it show codes even if the engine light isn't coming on?
Yes
thanks, i will try that.
Does a CFI have an IAC?