gentry20

my 91 pickup runs really good but when it warms up it idles high then low constantly. i was told it was one of the sensors. please help thank you.

pwd

I'm gonna hijack this thread for a bit, but it also might get the OP some answers.
Last night, I started up my truck and it was doing the same thing as described in the first post. I did have my truck in a wash during freezing weather, so I figured something might had frozen up, but it would mostly be under the hood right? The same thing happend this morning too and I notice the temp gauge was immediately warmer than normal running temperature. (I did have the block heater plugged in but it doesn't warm it up that much). Then it started to rev lower by about 1000rpms then jump to +100 rpms then back etc.. I was frustated and had to go to work so I took off even with it running like that. When I finished work, it seemed to start just fine and the temp guage was ok.

So my question to everyone would be, what could be the cause?

Things I'm going to check eventually include:coolant level and worn hoses

By the way, I accidently backed out of my driveway a few nights ago forgetting to unplugg the block heater, is there a way to know if the block heater still works?

toyota4x4907

Most likely you have air in the coolant lines due to the lack of coolant. Mine did the surging idle when my radiator blew.

go here: https://www.yotatech.com/forums/f116...ogging-157101/

pwd

Well after a very quick inspection, I did see a few drops of coolant under the truck. I popped the hood and noted the coolant seems to have sprayed out of the end of the upper rad hose which is practically new. I added some coolant to the reservoir. The next thing I should do is tighten the clamps on the hose. I will see how it starts up tomorrow. Its supposed to be -37C or -35F over the next few days so I plugged the battery warmer and block heater in.

pwd

Today I decided I would fire the truck up and see how it ran. There was still a small bit of slush in the rad overflow. It did the crazy idle thing, but not quite as harsh as it was about 10 degrees C cooler out. When I was driving, the temp show up to the RED right on H. So I pulled over a bit down the road and it cooled off a tad. It never did that before, so I checked underneath and it was leaking coolant, an almost constant stream. I shut it off for a few minutes and could hear a hissing sound which was coolant sort of leaking out of the back of the motor, very small amount but it was sort of coming out in bubbles. I topped the rad off with some water and drove it to a garage. It seems like my problem has gotten worse. My worst case estimate... a leaky head gasket. Unfortunatly I have no motor experience so I wouldn't know what to ckeck for. The garage is going to look at it on Tuesday and I'll see what they come up with in regards to the leaking coolant and crazy idle. From what i've read around hear, the off temp gauge and idle could simply be cause of low coolant level. By why the leaking antifreeze/ slushy antifreeze?

toyota4x4907

Head gaskets typically leak on the inside, not saying its impossible its an external leak, but internally is where most of the heat is at. It could be just a hose at the rear of the engine. Lets hope for that, ya?

Was the anti-freeze slushy after you drove it? If so, I have no idea. If it was slushy after sitting over night, then thats pretty normal. As far as I know, modern anti-freeze can't freeze solid, its the water you mix it with that freezes. The slushy anti-freeze is just from it getting cold.

kenbo53

v6 or 4cyl, my v6 has done the same thing and it was just air in the cooling system like toyota4x4907 said make its full then run it till its up to temp for awhile so the thermostat opens up then check it again once it cools back down enough. it took my several cycles to get it completely full but it fixed the problem and btw where did u find a place to stick a 10in sub all ive managed so far is to sony 4 1/2 in the factory locations but i cant thing or anywere to stick 2 6x9 where they wont be in the way of something

pwd

I had the truck at a garage yesterday, and he told me it "ran like a top". So I asked him if he wouldn't mind checking again, and he said he would. I went over to pick it up and it really did run just fine, no coolant leaks or anything. It ran fine today too, so maybe a combination of very cold weather and low coolant level caused all my grief. Hmm, well thats kind of a relief, at least I didn't have to pay for anything.

If my oil looks ok when I change it next, I'll think about getting a compression test done to see what kind of shape things are in. Anyone have an idea approx how much compression tests run?

araiza444

Hey Dudes!!


I also had the same surging idle problem. It first began by surging when I applied the brakes on my Toyota. Later on the problem progressed and moved on to my A/C. Every time I used my A/C it surged so if I pressed the brakes while the A/C was on, the surge would multiply. Finally the problem escalated to a continuous surge, but thanks to forums like this one, I was able to finally find a solution and understand what was actually going on with my truck.

I found that the surge is triggered by excessively high idle. This can be due to an incorrect timing setting on your distributor, faulty Air Flow Monitor (AFM), clogged EGR valve or clogged or malfunctioning idle air control valve or just an incorrect idle setting!

A couple of the items I have just listed were contributing to my issue (such as a clogged EGR valve). But my main problem, which I suspect is the same as most other people experience, was a clogged and malfunctioning Idle Air Control Valve. This thing caused me a fair amount of head aches for almost a year.

The purpose of this valve is to allow more air to enter the throttle body when the engine is cold, thus helping warm up the engine when needed. Once the Engine reaches a good temperature, then IAC valve shuts and allows the throttle body to regain control of the air management.

When this IAC valve is stuck open or clogged, it can maintains the open position, thus an allowing excessive amount of air to enter the intake and forcing the idle to increase to a point where the computer looses control. This causes the Toyota computer to repeatedly scan for an appropriate idle, fuel, timing, combination to compensate for this excessive air coming into the engine, thus never finding an appropriate combination and scanning forever in an infinite loop. The higher, the air coming in through the intake, the faster your idle becomes and the faster the surging or computer scanning will occur.

If your Toyota truck is surging uncontrollably and doesn’t seem to respond to any sort of idle or air adjustments, then first look at your Idle Air Control Valve. You can verify that your IAC is either working properly or not by disconnecting your throttle position sensor and then starting up your truck. If your engine idles excessively high with the throttle position sensor disconnected and is still un-adjustable, then there is a good chance that your IAC valve is not working properly. If your engineer continues to act up with throttle position sensor disconnected, then maybe your problem might be due to a clogged EGR.

You can clean your IAC valve and get your idle back to normal (without having to spend $130 +) by removing it from the throttle body and soaking it into a carburetor/pars cleaner solution for a few hours and then blowing out the valve and both coolant passage tubes with compressed air. Then reinstalling it back on your throttle body.

You can also use this method to clean a clogged EGR if necessary, just be sure that you don’t soak the vacuum valve part. I’m not sure, but I don’t believe it will like the cleaning solution!!!

Anyway, I hope this stuff will help at least one person. When researching a solution for this problem, I found many, many people experiencing the same issue, but never really finding a solution.

pwd

Thanks for that reply araiza444! That looks like some great information. I'll have to try cleaning my idle air control valve. Glad you came to Yotatech.

Bako88

Does the 22RE have the same type of idle air valve? Isn't it mounted below the intake with a 5/8" - 3/4" tube running up to the TB?

Bako88

I tested the temp sensor located at the front of the intake (truck won't run when unplugged) and want to see if anyone in this forum knows if my results are normal. I took only 2 readings. Cold = 3.4 K ohm & Normal oper temp = 0.2 K Ohm. I read some where that cold should be 1.4 and warm should be 0.2.