Engine idle problems

[Joet]

Hi guys,
Having a problem with the idle of my 97' 1fzfe.

Slowly been creeping up to 1000/1200rpm hot and cold. Then for some reason after driving on the highway I noticed it was idling at 1600/1800!

So checked the following;
-vacuum hoses for leaks
-air intake hose for splits
-iac valve - cleaned it and can hear it working
-tps cleaned and seems ok
-maf recently cleaned
-cables and linkages all seem good
-taken the a/c belt off to check - same problem

Wondering if valves that need adjustment would cause this problem? Last checked them 30k km ago and a few were near the upper and lower tolerances.

Can't seem to find a big brass screw by the efi unit that I've seen mentioned causing idle issues.

Going to do the fault code sequence as described in fsm.

As always any input appreciated!

 

[ajax1]

Make sure your peddle isn't sticking next time iris revving high stick your toes under the peddle and pull up, if this is the case you needs new cable

 

[jonheld]

What @ajax1 said. Always check the simple things first.
There should be slack in the throttle cable when the throttle plate is resting on the idle end stop, and with the pedal floored the throttle plate should just be touching the WOT end stop.
If you or the PO installed a hand throttle make sure that is set up correctly as well.

 

[LuckySomer]

If you don't mind me asking. How do you clean the MAF on an 80? Picked up a can of MAF cleaner but the sensor looks to be buried in the Toyota unit

 

[ZumSteel]

I had the same issue with my 94 and wound up doing this mod http://www.lcool.org/technical/80_series/fast_idle/fast_idle.html it solved the issue, been working fine for 18k miles. I think i will eventually have to buy a new iac, but they are pretty expensive.

 

[Kernal]

LuckySomer: DO NOT OPEN that part, it is not a MAF and there are NO serviceable parts inside, if you attempt to open it you will pull a few wires off a circuit board and it will be ruined (suggest you start a new thread if you need help with diagnosing a problem ).

 

[doxster22]

I just had a similar issue with my 94. Finally tracked down the problem to one of the curved metal vacuum lines coming out of the throttle body. I took the throttle body off to clean it (although this is not necessary to unclog line but I didn't know what the problem was before I took it off) and found one of those ports completely clogged. I could not even force mechanics wire through the port to unclog it at first. I sprayed come TB cleaner and let it soak and then kept forcing mechanics wire through. Had to repeat this process three or 4 times to finally break it all loose and get a steady stream of cleaner to run through the port. Put everything back together, fired it up. It still idled high for about 10 minutes until it "relearned" the base idle. Since then, I idle at about 1100rpm when cold and 800 or so when warm. Before I did this, my truck would idle at 1900rpm when cold and over 1200 when warm.

Take your throttle body off and give it a thorough cleaning, especially if you have never done it before. Also, there is a port into the upper intake that will get clogged up with carbon, clean that out too while you are at it.