MX-3.com

Ok so i went out of town for a week and my car was running good slight idle issue. when it was warmed up it would flucuate (i know its not spelled right) between 500-1000 RPMs. now i got back sunday and it is a really rough idle almost cut off on me yesterday. i have recently changed the PLUGSS, WIRES, ROTOR, CAP, And FUEL FILTER. i was talking to someone about it and they said maybe the throttle positioning sensor. Does this sound right or does anyone have a better idea of what it might be. I could really use a hand hand here so thanks for any help

First thing to do would be to check for CEL codes. Rather than just replacing stuff and throwing money at the problem.. see if you can figure out what the problem is.

Rough idle is usually a result of a vacuum leak. Fluctuating idle can be caused by numerous things.. dirty throttle body, vacuum leak, bad coolant temp sensor, sticking IAC valve.. etc.

Start by checking CEL codes.

Tunes67

Ok so i tryed to pull codes from the CEL but i didnt get any. then looked closely at the intake tubing and found it was not tight. After tightening it started to run alot better however when it is warmed up it still goes from about 1000-500 RPMs i checked to see if there where and vacum leaks any where else but could not find any. So where do i go from here.

ok so i read the thread that kingfd started about his idle problem and it seems that everyone is having this problem so iam am going to try the coolant temp sensor and see if that solves my problem. wish me luck

you may also want to check that large ribbed intake tube that goes into the throttle body. check the ribs for cracks. that's what happened on my escort gt (it was throwing codes though).

If it was your coolant temp sensor.. it would throw a code 8.

Tunes67

Mine only does the idle search every once and a while. My main problems when it was bad ->
1. Leaking air in intake tube
2. Leaking air from tube going into the brake booster
3. Coolant temp sensor (didn't throw a code for me - I changed it and it helped a lot. Cheap too. Then tested it at home and it was indeed bad.check manual for testing instructions)
4. Idle was not set right.


after I fixed all that, it runs good at about 700 to 800 rpm at most temps. Rarely does the searching idle, and never stalls or even close too.

I plan on getting the head reman'd but that's later in the season.

I would bet the actual problem was the air leaking from the brake booster; that would kill your idle big time...