I need help figuring out my idle problem
 

First off it's an 85' model 22RE.

I just did a cylinder head swap this weekend which is also nothing
new to me because I have done this 2 times before. I have everything
installed and connected properly. I have gone over every spot that there
might be a vacuum leak and can't seem to find anything that makes a
difference although it has improved and isn't idling as crappy as it was
before. I did find a few potential vacuum leak spots but they have been fixed.

It will idle perfectly sometimes or a little too high but most of the time
it will idle like it's got some huge cam in it and sounds like a race car
as well as shaking the whole truck back and forth, then it will
eventually die but starts right back up. Then it might decide to idle
perfectly smooth?!?!

The cylinder head is brand new, even the cam. I was thinking maybe since
it's gradually improving that the cam and cylinder head just need some time
to break in.

I'm out of options at this point besides maybe going with a
different spark plug. I was finally talked into buying Bosch Platinums but now
I'm thinking that might be the problem.

Any other ideas? Maybe Idle Air Control Valve?

Other than the idle issue, the truck runs great. Doesn't burn oil, has slight
increase in low to mid range power.

Overall a problem free upgrade except for this idle issue but I did have problems
with the truck idling low after starting it warm and if it sat for a few hours, it would
take a few turn overs before it would start to idle and that was before the swap.

Anyone? Or does no one want to read it because I typed too much? :D

Throw some NGK or Denso plugs in there first. If any other plugs besides one of these is used, the engine will most likely misfire and act up.

That's what I was thinking because that is the only thing I changed other than
the cylinder head which I doubt would cause this issue since it's running much
better than it did before but just can't hold a smooth idle below 1k.

Well it wasn't the spark plugs :bang:

yeah. I wish i could have warned you. Honest, the spark plug thing might cause a minor manual stick vibration but nothing like what you are describing. If you think it's a vacum leak, check for it using brake clean, or even better a bottle of propane and a small hose to isolate the leak.
You prolly already did this, so might i direct you to your throttle body to check the TPS. If you aren't familiar with it search for it and you'll see that many of the symptoms you have are parallel with that of a tps issue. Maybe not the shaking though, so don't go out and buy a new one! If you can get your hands on an OHM meter and a feeler gauge check it to see that it's functioning properly. It's more sensitive then the valves so take care with it. I'm battling with mine right now, odd idle speed, rough idle but not to the point where the truck dies.

Well it idled ok before I did the head swap. I did have this problem to an extent but nothing like this. It would hold an idle and slowly die when it was cold but with the new cylinder head, it does it quickly. Sometimes I don't even notice after it's warm and other times I have to give it gas to keep it going. I did take apart the IACV and poked at it a little bit during the swap because of the low idle I had before. I'm thinking it might be stuck and just barely moving or not giving out the proper reading.

The MAF meter had been opened up before I owned the truck and now with the new cylinder head working better might have thrown it off? I'm still leaning toward the idle air control valve because of the low idle I had before. The thing is, it would idle after I drove around before the head swap.

I think the TPS sensor is probably working properly because I can time the truck still and haven't touched it since I bought the truck. I have seriously gone over everything that could cause a vacuum leak and can't find anything else. I've even sprayed around.

EDIT:: Double post...stupid work computer :chair:

well if you cleaned your throttle body when you did the head with any corrosive cleaner save for throttle body cleaner (ie gas) you prolly up your tps. That's what i had done. It was nice and clean afterwards though :) well if your soo sure it's the AFM then you might wanna open it up, but be warned it's sensitive equipment as well and if the PO didn't mark the unmodified setting you'll have a tough time figuring out which tooth it was. Good luck.

TPS was perfect. I messed with the IACV again and my truck actually idles
more than it did before. I'm thinking the valve probably finally decided to stop
working. It does have 237k miles on it. Not matter if it's hot or cold, the valve
opening never changes...or at least, I've never seen it.

Did you check your DASH POT, I had this problem, and it turned out to be the dashpot

If the valve opening never changes, then the heating element in the auxiliary air valve is fried (make sure it?s plugged in though). I fried mine by cleaning out the passages in the throttle body without removing the hose. They're a little on the expensive side, but you can get them at a discount from 1sttoyotaparts.com.

yeah, again have you checked your DASH POT ? You keep on mentioning this IACV and I honestly don't know what you are talking about. I have had idle issues B4 it's been my TPS the DASH POT more than once and just recently throttle cable linkage after the Body Lift. So good luck, and wish i could have been more help.

The dash pot still works and hasn't been adjusted so I'd think it would still work.
IACV is idle air control valve. This thing http://www.autopartswarehouse.com/bi...1986+1987+1988

and it's the only thing I messed with/cleaned when I swapped the cylinder head. I also did the fuel filter but I'd think it wouldn't be the problem at idle only.

idle return spring? just an idea.

It's really not an IAC valve since there is no stepper motor continuously controlling the flow of air for the idle. That's why a vacuum leak causes the motor to stumble and stall in these trucks.

Anyway......that's the proper part you posted. You can get it off of 1sttoyotaparts for cheaper than that price. I have the original Toyota microfiche slides at home and I can give you the part # for the valve later on tonight.

You'll never get the idle to come down with the valve continuously cracked open. However, there is an adjustment on side (if my memory serves me correctly, the nut is a 7mm) of the valve and it can be adjusted to where the valve never opens and is continuously closed. Your right foot will have to be the cold fast idle for the first couple of minutes, but the hot idle will be normal.

Awwwww, memories of my toasted air valve:laugh:

I had that problem on my 89 and there is a small coolant line going to the throttle body and i took it loose at the throttle body and blew air into it from my air compressor and it fixed it. not saying it will fix yours but it would be worth a try. I had a guy adjust my tps and i told him what i did and he said he does the same thing at the shop to fix that problem too.
edit: my idle was to high also even with the idle screw turned all the way down and the engine loped but at times it wouldn't.
highway

I suppose I'll take it all the way off and check it out and clean the passages to
see if I can save the $100+

I found a really cheap one on ebay though.