93yota$$

Hi all, I am new to the forum, below I will list details of the truck.

I know this issue has been discussed many times on the web, but I am having an issue finding the Culprit to my high idle problem. If I cover the hole in the TB for the iac valve the truck idles farely normal maybe a little too low when it’s cold, but still idles on its own. I have replaced the iac valve and still have a high idle, again if I plug the hole the idle drops down. I have checked the coolant lines they seem to be working fine... made a huge mess...

thoughts?

1993 xtra cab
22re from 94 truck
holley in line fuel pump
auto meter gauges ( no stock instruments)
5 speed manual
ford 9”, 6.0 gears moser spool
ford Dana 44 front hubs
35” tires, 15” wheel
long travel suspension (ask for details)

millball

Have you made any attempt to adjust the idle air screw on the top of the throttle body??

93yota$$

Thank you for the reply.

I have pinned the idle screw down does not make a difference, I have ordered I new idle screw, just in case mine is bad.

the truck was running great after I did the engine swap, then I let it sit for about a year, and went to start it and had this idle issue.

Do you think the aftermarket IAC valve needs to be adjusted? I have tried 2 of them ( one from Napa and one from Autozone,) the both seem to function the same

Dernation

Since replacing it isn't working, I'm not sure how your IAC is controlled but it may have a problem with being under vacuum/ not under vacuum, or have power/ not have power, or polarity reversed. Maybe a bad controlling system?

93yota$$

The iac, is controlled by coolant as the coolant heats up the valve closes, there are no vacuum lines going to the valve.

and I have checked for vacuum leaks and haven’t found any. And as mentioned above if delete the iac buy covering the hole, the truck idles fine.

my thoughts are, either the iac needs to be adjusted, or the secondary fuel injector is not functional, or maybe I am loosing fuel pressure somewhere, but I don’t know...

Dernation

So what are the hot and cold idle rpms?

2ToyGuy

Chances are, if the idle adjust screw makes no difference in the idle, one of two things could be the trouble.
First, are you adjusting the idle adjust screw, and not the big cover screw over it? A lot of first time idle adjusters mistake the cover screw for the idle adjuster screw. Not that *I* did that...ahem...more than once, anyway.
Second, did you make sure you screwed the idle adjust screw all the way down, so you could count the turns, and parts of turns, it was from the bottom? That way, you know where your starting point is. Then unscrew it all the way and see what the condition of the o-ring on it is in. The o-ring is frequently old and degraded, or disintegrating. You can pick up a set of o-rings at Harbor Freight, or most auto parts stores, that has an o-ring in it small enough to replace the one on the idle adjust screw. Put a thin layer of Vaseline or silicone dielectric grease on it before installation. It will make it last a lot longer, and get a better seal.

Cheaper than replacing the idle adjust screw completely, anyway.

Good luck!
Pat☺

93yota$$

Thank you Pat, I actually did replace the oring on the idle screw thinking that was the issue, but it did not help, if i pinn the idle screw all the way down, or remove the screw entirely the Idle does not seem to change. However the idle screw looked old and a bit rusty, so i ordered a new one, should be here soon. i just ordered the conversion plug for the toyota diagnostics to OB2, assuming the adapter actually works, i will report back with Idle numbers and codes.

my tach is broken, so as of now i do not know the rpm, but i have owned this engine for over 10 years and did the transplant about 8 years ago ( i was t- boned and the original truck was totalled) it sounds to me like it is idleing at around 2000 rpm, i have left the truck idling for 5 minutes to see if it would slow down as the coolant heated up, but it did not.

2ToyGuy

Could the air passage be clogged up somehow? Throttle bodies are known for getting gunked up, since the EGR goes into it with no filtration of any sort. Pretty easy to verify. Just pull the idle adjust screw out, and spray some carb cleaner into it, using the long red tube they provide. Good idea to pull the big air tube from the AFM, and put a rag in the big inlet in the TB to prevent any cleaner from going where it shouldn't. Probably a good idea, too, to pull the tube from the IACV, and plug it with a rag as well.
I would think that a clog would cause it to idle low, or not at all, but stranger things have happened, I guess.

Having said all that, another thought that occurs to me is that the stop for the throttle cable is mis-adjusted? So that the throttle plate is held open further than it should be. Or the throttle plate is sticking just slightly open, thus bypassing the whole idle portion of the throttle body. Could one of those be a possibility as to why the idle adjust screw has no effect?
Just a thought. I get so few any more...

Pat☺

snippits

Sticking dash pot was causing my 92 22RE to have high idle. Bought a throttle spring from NAPA, and that fixed it, but it changed the feel of the gas pedal. Finally, uninstalled the dash pot, and that was the end of that mess. Did that round about four years ago, and it runs just fine.

2ToyGuy

I put a second, heavier spring on my 87 4Runner years ago. It really helped with the feel of the gas pedal. Until I did that, it seemed as though I would just touch the pedal, and the engine would over-rev before I could start letting out the clutch.
Granted, I have big feet, and they're mostly numb, other than the pain I feel, from diabetes, but I should have better control than THAT.
The secondary spring really made a huge difference. Now, I can bring the RPM up as I let off the clutch. In other words, properly.

Have fun!
Pat☺

93yota$$

Hey everybody,

thanks for all the input, turns out Patt was right. The air passage at the idle screw was pretty gunked up, I cleaned it, problem solved.

when I originally removed and cleaned the Tb, I did not remove the idle screw and clean the air passage. 🧐, the inlet side of the Tb was fairly clean so I was kind of surprised when I found the idle air passage so dirty. Specifically, I believe the issue was a generous build up of carbon on one side of idle screw “retainer” threads, and at the bottom of the “screw valve seat”, that was not allowing to screw to tighten down any further, leaving it open.

since this is an off road vehicle I’m considering removing my egr system, hoping to reduce this type of build up