What should I be idling at?

[Markek]

I have a 2001 Sport Trac with 82,000 miles. I purchased this awhile ago for my son so I'm not the daily driver.

Was in it today and when stopped at a red light it pulses back and forth from 500 - 600 rpms. This seems low to me. Otherwise it feels like it runs pretty good. Was wondering if anyone had any suggestions. Just had a complete exhaust put on but I think it was idling this way before the exhaust as well. Thanks.

 

[koda2000]

Around 600-650 is pretty normal for the SOHC. If the idle varies, it may be time for a tune-up. If the idle is high it could be a vacuum leak or intake gaskets/O-rings.

You can start by cleaning the IAC, MAF and Throttle body.

 

[gtyates]

Is your low idle condition a cold weather issue only? My '05 idles around 600 in cold weather (below 40 ambient temp) but otherwise idles @750. When idling at the lower 600 it feels a little rough and honestly doesn't feel right to me, but it is a steady 600 and otherwise drives great. My truck has done this every winter all 6 years I have owned it. I have replaced various minor things like the IAC, MAF, coolant temp sensor, and cleaned throttle body, but no difference on cold weather idle. So I say all of this to simply respond that if this a cold weather low idle issue only then it may be normal for your 'Trac. My 'Trac had 55k when I bought it and now has 111k.

 

[Markek]

Right now it's about 29 degrees but I don't think it's a cold weather thing because I don't recall it being like this before. I did clean the IAC, MAF and Throttle body this summer.

I think idling at 600 feels pretty good to me but when it pulses down to 500 it feels like it may stall.

Tune up could be the answer.