Idle speed fluctuating

[formula]

I've noticed that my idle speed has some level of fluctuation. Seems to be linked to temperature. I never paid much attention to idle speed until the installation of the POD's, at which point I had to lower the idle after adjusting the fuel screw. Piers said to set idle at 850 to prevent lugging the engine when stopped in gear with AC on, etc. I installed the injectors in july when temps here were in the 80's. Now with the colder weather my idle is creeping up to almost 1000rpm. Maybe this is due to the KSB timing advance kicking in. But when I unplug the KSB the idle only drops about 50rpm. I've heard that strange idle speeds can be an indication that things are going bad inside the pump. Idle is very smooth, fuel filter is new, WOT is , everything else seems to be functioning fine.



Any input is much appreciated.



SP

 

[nascar mark]

KSB is only activated when engine temp is below 90 deg at start up. If engine temps are warmer then that and you take ksb wire off and notice a drop in rpm's, then the sensor at top/ back of intake is cycling on and off, which is not normal. Sensor could be bad.



mark

 

[formula]

The temp sensor and wiring harness for the KSB are new. The sensor went up in smoke a couple of months ago along with the little wiring harness that connects it to the KSB and the shutoff solenoid. So, the temp sensor and the KSB solenoid are functioning properly. Oh, also, after posting this I went and checked the locknut for the idle speed screw (just in case) but it's nice and tight.



SP

 

[nascar mark]

Wouldn't be the first time a new part was not working right. With warm engine pull wire to ksb when you notice high idleing. If rpm's drop then senor is shot. Worth a try.



mark

 

[formula]

Just got home from work. After 30 mile drive on the highway with everything nice and warmed up I checked the KSB. It's about 35 degrees here right now so the whole intake manifold and the KSB temp switch were cold to the touch (probably below 60 degrees). Engine was idling steady at 950. Pulled the wire off the KSB solenoid and there was a slight change in engine sound, about a 20 rpm drop and a bit more idle smoke. I'm assuming that this is because the KSB was on and the timing retarded slightly when unplugged. I did this same test in the warmer weather and KSB does shut off when the intake gets hot. Oh, this morning on the way to work, after the same drive, it was idling at 1000rpm. I'm going to try loosening the throttle linkage a bit and putting some lube on the breakover spring.

 

[glhs]

I've owned three 1st gen trucks and all of them idled about 100-150 rpm more in the winter once the engine is at operating temperature. They don't like the hot summer days.