fountain

I believe I have an IAC problem. The truck has been running great up until a few days ago. The symptoms lead me to believe it痴 the iac and I知 looking for confirmation. On cold start, the truck idles high like normal, but I知 getting a strong gas smell from the exhaust. It keeps a higher than normal idle when warm and will surge at times. From reading here and some YouTube videos, I知 seeing the iac as normally the culprit.

Coolant level is good as well and the heat works as it should.

2ToyGuy

Could the Cold Start Injector be staying on? Maybe the timer for it not shutting it down correctly? Maybe it's leaking?

Failing that, have you checked the Idle Adjust Screw for having a bad o-ring on it? The one under the large cover screw on the left side of the TPS, as you face the truck, looking aft from the front. After all, if it's factory original, it's 30 years old. It's a small o-ring, readily available in the kits sold in places like Harbor Freight, and most auto parts stores.
Make sure to count how many turns out it is before you pull it out. Just screw it down until it bottoms out, counting the turns, including fractional turns. Then, you can screw it out to check and/or replace, it's o-ring.
A note on that: Apply a very thin coating of Vaseline to the o-ring before you screw the ICS back in. It will make it last a lot longer, and make screwing it in or out much easier. This is a good idea to to to ANY rubber you work with. A thin coating of Vaseline will make things a lot easier. I put a coating on my door seals every fall. Prevents them from freezing closed on those really cold mornings, and my door seals are still in very good shape, even after all these years. I put Vaseline on ANY o-ring I work on, replacing them or not. Any rubber I work on, really. It really seems to do a great job.

If it IS the IAC, you can get a new one on line. Surprizingly they're fairly readily available. If you do go to replace it, it might be a good idea to check and/or replace all the small water hoses under the Throttle body. After all, THEY may well be 30+ years old too. Do it now, to prevent a rupture on the highway, or worse, when you're off-roading someplace no tow truck can get to.
Just a thought. I get so few of them, and they die of lonliness pretty fast...
Pat☺

87-4runner

The last time I had contrive valve issues the feds showed up and ask more than a few questions about the disappearance of 1.7 million in bonds that were allegedly in my possession. I hate it when the contrive valve goes south...

fountain

Ok, still looking into this and trying to diagnose it best I can without throwing parts at it. I checked for cel and got 42. Would that have anything to do with why it’s idling high when warm, surging and smelling like raw gas at high idle cold?

2ToyGuy

Are you certain it's 42 and not 41? I ask because 41 indicates a bad TPS. A very valid possibility. The 42 code indicates vehicle speed circuit, or the ECU. I am not certain how that could have the effects you describe, but I guess it could.

Did you take a piece of tissue paper, or even regular paper, and check all the injectors, including the CSI, along with the fuel filter, the fuel rail, and so on, for fuel leaks? Just run the paper around the suspect area, and the paper will pick up any leaking fuel so you can see it easily.
Another possibility I can think of is a leaky injector. You'll have to pull the fuel rail off so you can pull the injectors. There's a procedure in the FSM on how to check them for leaks, using the fuel supply from the truck to see if they leak.
Be aware that if you remove the injectors, you'll need a set of o-rings and so forth to re-install them.
Also, if you open any fuel connection that uses a crush washer, you MUST replace it. You can NOT reuse crush washers, at any time. You screw down onto a crush washer, even a little bit, realize you forgot something and loosen it back off, new crush washer. Always buy a number of washers for every fitting you might even consider removing before you start. No matter how careful you are, you will invariably need several washers for every connection you even look at.
Also, be aware that if you're down to the last washer for a particular fitting, when you go to install it, the washer WILL leap out of your hand, LEAP I say, fall to the ground under the truck, and vanish. They're quite malicious that way.
Same with the injector o-rings, and rubber fittings. Don't reuse them.

Hope you find the trouble easily!
Pat☺

snippits

Do resistance test on Thermal Time Switch and ECU temperature switch. Test them both on hot and cold coolant. They are right beside each other, and they are easy to test. TTS turns on the cold start injector. TTS usually sticks hot which means rough cold starts. If it's sticking cold, then it could possibly be keeping the cold start injector on, but it would fire right up cold. That's why you need to test hot and cold.

While you are at it test the throttle position sensor too.

fountain

I took the throttle body assembly off and cleaned everything the best I could and it seems better now. The 42 code could be relevant to the speed sensor on the tranny not working and the speedo not working maybe? Maybe it will continue run decent