Weird idle

[nicnmike]

I've got a 1990 3vze with about 170k on the clock. I haven't had the truck long, and it wasn't exactly in great shape when I got it, so I've been nursing it back to health these past few weeks. I've just about got the idle dialed in, but it's doing a weird thing. This morning it was around 40 F out. My truck started off around 1200 to 1500 rpm when I first started it and stayed that way for a little bit. It slowly came down as it warmed up, but never really dropped below 900. I thought that was a little high, I had adjusted it last night to around 750-800 rpm. This afternoon, it got to be around 75-80 F, so much warmer. After driving around for a bit the idle settled down to about 500 rpm. It idled fine there, so I didn't worry too much, but is this normal? Should the idle fluctuate based on ambient temp?

 

[4runner86]

Have you checked to ensure that all of your vacuum lines are connected? Also I am not sure if you know about the 3.0, but it seems to require a lot of attention. It does last a long time, but it will nickel and dime you to death. Mine does the same thing man, I kinda just roll with it. I figure seeing how it gets 13mpg, maybe the low idle is good for it once it heats up. Also just for some future concerns, the transmission does not shift into 4th until the engine is at operating temp. So if you happen to notice it wont shift into the high gear until your 5 miles down the road, its normal. You vacuum diagram in under the hood.

 

[crutchy]

It should idle a little higher when cold, but should even out at about 800 when warmed up. I just went through this with my new one. Vacuum lines, clean VAFM, throttle body, seafoam it, plugs, wires, cap, rotor, new coolant temp switch, set the timing. Seems like a lot, but the cost is minimal and it only takes an afternoon at worst. Mine started idling anywhere between 600-2000 and getting 10 mpg city with little to no power (265k on the clock). Now she idles dead at 800 up to 15 mpg city with some decent power. Good luck man.

 

[mikebontoft]

check your throttle linkage... Mine will stick (but I can't find where, I suspect still in the throttle body somewhere) and if you give it a light push to close the throttle it will sit there where it should.