when i did my 3.suck rebuild i bypassed the IAC/TB coolant line, i used some steel braided hose and took it up and over the phlenum so the flow would not be interupted. now... i did this because i wanted to keep intake temperatures down and i saw that running hot coolant through the TB as the key heat source in the system. the IAC operates on coolant temperature, so does anyone know if the IAC not getting coolant would be harmful? heres my guess:

the IAC stays open longer and after the TB heats up indirectly then the IAC should heat up and close, just causing a longer high-idle after start up. but.... the indirect heat may not be enough to close the valve causing poor gas mileage perhaps?

:/ anyone else have any thoughts on this?

 

I think it would cause a surging/bouncing idle if it is idling too high. The ECU will see the engine at operating temp and see the idle too high so it will start cutting fuel. Low coolant level is a major cause of this problem, and I would imagine no coolant would cause the same problem.

Have you been running it this way for a while? No problems with idle surge?

 

yeah for like 1500 miles now. i noticed my idle screw doesn't do anything anymore and my idle is usually 900-1000 but when its warm it will sometimes drop to 500-600. i'm probably going to switch it back to how its supposed to be lol.

 

im not sure how your 95 works, but if its the same as mine it uses the coolant and a bi-metallic strip.

 

I ran my 22re w/ that line looped. At cold start, the idle was about 500rpm. I had NO cold start high idle, which made the truck take forever to warm up at idle. I put the lines back where they should be and enjoy a cold start high idle.

 

so i put those coolant lines back today... had a few too many before i went out in the garage to do it... and i was sitting in the 4runner trying to start it afterwards.... crank, crank, crank. no start. my dad came out and noticed my EFI fuse on the work bench... DOH! i forgot i pulled it so the ECU would re-map.



my idle doesn't surge anymore and i notice better throttle response.

 

Go figure.