newTOyotas

FWIW, it gets pretty cold here and has been the last few mornings (at or around 0 degrees). I have been running the IAC blocked for a few days now, and you will definitely notice it is a little harder to start only when the motor is completly cold (first thing in the morning). I just give the throttle a little tap or two while it is turning over and it fires right up. I keep the rpms at or around 1500 for about 20-30 seconds. I then go back inside for 15-20 minutes and am pleasantly surprised that the motor NEVER does the up/down/up/down/up/down/etc/etc idle ever anymore. The CLUNK I had a second after letting off the throttle or getting back into the throttle going down the road is completely gone, and the motor starts/idles better than ever when warm since I've owned this truck. Like I've said before, the IAC is probably a great thing to have when it is working correctly, but if it isn't and a person is sick of all the BS that seems to come along with that I think most anyone will glady trade that for an engine that takes a second longer to start only when cold.

makemusic116

So I tried to start my truck with the IACV disabled once it was cold...no go. Would start but not run. So I pulled it off and put it back together and guess what...it still wouldn't run and still won't. I have no clue what happened but it starts and then just stalls out. I left it at work I am going to have one of my techs look at it tomorrow...

newTOyotas

When you eliminate the IAC, you are eliminating something that the factory put there for a reason. As long as you can start the truck and feather/pump the gas a few times then find a spot in pedal travel to keep the engine running at or around 1500 rpms for less than a minute, it will then stay running by itself. You can then just walk away while your truck warms up.
If you were having the same problems as I was, having a motor that takes a minute to start while cold is FAR FAR FAR better than a motor that you can't stand driving at any engine temp. I like driving through the drivethru at the bank and fast food places with out my motor reving up and down over and over again.
When the engine is warm it will still run as it should. It only takes a little effort when the engine's completely cold. I say a little effort because IMO it isn't anything at all to get my truck started even in the coldest temps with the IAC blocked off. Of course I am 35 years old and started driving cars when they still had a carb on top of the engine. You're not going to just turn the key and walk away with the IAC blocked off when the engine is cold.

makemusic116

Well it turns out the reason my truck wouldn't run had nothing at all to do with the IACV. The mass airflow sensor ˟˟˟˟ the bed and was sending a signal to the fuel pump killing it so it would not run. A $50 junk yard mass airflow sensor and it started up and ran fine...but still surges. I am going to call the same junkyard and see about getting a throttle body and IACV and see if that fixes the issue. I replaced the plugs, wires and distributor cap too just as maintenance, which turned out to be quite necessary the plugs were HORRIBLE. If the IACV doesn't fix the idle issue I am going to drive it off a cliff.

newTOyotas

Well, I hope it all works out for you after all of this BS.
I have owned my first ever toyota for about 2 months now. Every day that I've owned it the thought of full coverage insurance, me bailing out the door at the last second, and this POS flying off the highest point of a cliff brings a smile to my face.

makemusic116

I hear that man. I have owned a lot of Toyota's including an '88 Pickup with the same motor and no issues at all with any of them they were all super reliable. This truck is just getting up there in age and once this is fixed I may not even have anymore issues with it. Luckily mine only surges for a few minutes during warm up and not all the time. Once it warms up it doesn't do it at all and runs perfectly fine, which only leads me more to believe that its the IACV. Money is just super tight right now and its hard taking care of my familys needs and dumping money into my truck trying to fix it all the time. I am probably going to sell it after going through all this and get something different. Overall it has been good to me but I feel like this may be the start of more problems to come and I don't have the time or energy to work on my vehicle constantly. I miss my old Jeep where parts were super cheap and very readily available. I am just at my breaking point with this idle crap

newTOyotas

I've always pretty much owned chevys and have always been happy with them for the most part. I got this toyota to replace my 98 ext cab w/3rd door 4x4 Z71 because of the rising fuel costs and the fact that the truck got 12-14 mpg with my driving habits. Man was it a huge letdown when I found this very basic truck that is 1500 lbs lighter was only getting 14-15 mpg (checked closely since the fuel gauge only works for the first 50 miles after fill-up ).
I'm sure if I had the time/patience to try and figure out even the basics of this very foriegn to me truck, then I would have a better review of it but I just don't.
I paid more for it than I should have so it only adds to my frustration when it doesn't even run right a month after I bought it and the info I am trying to absorb about the truck/engine all seems incomplete/inaccurate or negative.
Anyways, good luck to you. I have been working on 'rebuilding' a complete bolt-on throttlebody that wil hopefully let me focus on the list of other things that need attention desperately.

makemusic116

So I bit the bullet and I spent the $140 and bought the idle air control valve. It is supposed to be in on Friday and depending on how things go I may put it in Friday night. I can only hope to hell this fixes it because I am so sick of dealing with a truck that revs up at stop lights randomly...

Fixed So Far...
1. radiator
2. coolant temp sensor
3. mass airflow sensor

Possibilites Left...
1. IACV?
2. TPS?
3. Vacuum leak?

sebastianholmes

i dont know if you have AC or if you use it but i got rid of my IACV and use my AC buttin for cold starts, just back the white screw on the intake out a good ways and when you start it push the AC buttin and turn the fan on 1 click and an amazing perfect idle around 1500rpms, works like a charm for me

SoCal4Running

Id look into the vacuum leak, its what fixed mine before someone stole my truck from work yesterday.

makemusic116

I am not convinced that it is a vacuum leak only because it doesn't do it all the time. It seems to act up when cold then stops once it warms up which seems to be directly related to coolant which means IAC. I have thought this all along I was just being cheap and not wanting to spend the money but the part is paid for and on order so we'll find out.

On another note...some stole your truck?

SoCal4Running

Yup unfortunatly it's gone.

makemusic116

˟˟˟˟ man that sucks. Well at least whoever stole it won't have idle issues with it

makemusic116

So...

I replaced the Idle Air Control Valve and...

It still surges

It idles good and as it warms up the idle climbs and then begins to surge...

I am at a total loss for what the hell it could be...

TPS?

uplandretriever

ok seems i have the same problem or similar to some of you. Have a new short block with about 10,000 miles and its been running great. we had a spell of negative weather and i got fuel from a place i never get it. now my truck will not idle when the motor warms up. i can start the truck when its cold and it idles fine. once warmed up when you pull to a stop and put in neutral the truck will die. no loss of power going down the road. Does anyone know what this could be? Just put a new radiator in it tonight and drove 20-30 miles but still same problem. also fueled up with premium full but still no change. if i turn up the idle screw is this going to hurt anything ? in my opinion that woudl be just a short fix. 91 truck 22re

thanks for the help

XtraSlow_XtraCab

makemusic,

In my signature is a link to a list of free, downloadable FSM's. It would be worthwhile to test the variable resistance in your TPS via a multimeter. I have seen TPS's result in such idle surges on multiple fuel injected vehicles from a 1977 Datsun 280z, to a 1989 Toyota 22RE, down to an early 90's POS wannabe racer Civic.

On a Datsun 280Z engine, the TPS isn't CRUCIAL but more of a "fine tuning" device for fuel mixture. The engine still ran even when I reached over and unplugged the TPS. The surging idle ceased on top of which. Unfortunately, I can't tell you if the 22RE responds the same way.

After discussion of why the TPS's on both vehicles went out WHEN they did, it was discovered that these occurences took place after a thorough pressure washing of the engine. The disadvantage of devices that take a physical motion and divert it into an electrial occurence is that dust, water and other crap seems to find its way into the tiny spaces.


If there are any Pick N Pulls, or similar self-serving yards, in your area I would suggest a pair of good deep pocket cargo pants and just rip yourself off a couple TPS's and leave with full pockets. I typically don't invoke stealing, but more than likely you'll be charged an unfair price for an unwarrantied, used product. And when push comes to shove, I know it won't be me that gets shafted.

Anyway the factory service manual is, IMHO, the most trustworthy piece of literature and every component of the EFI system can be tested with a multimeter and, in some cases, a pot of boiling water.

makemusic116

I was kind of thinking the TPS was the next step too I am definitely going to try that. Luckily I am a Service Manager at an auto shop and we carry parts as well so I have the luxury of sending it back as defective if it doesn't work. I have been working on/with cars most of my professional life and I have never been so stumped by something. What is funny about what you said is that when I installed my IACV I had forgot to plug in my TPS back in and it ran fine but when I plugged it in again it idled rough and started surging. I am going to try that next and see what happens thank you so much for the advice it is very much appreciated

makemusic116

So I finally solved the idle mystery today...

I had kinda thought this but I was in denial. I block tested it and sure enough it needs a head gasket...

500 in parts later the mystery is solved.

uplandretriever

How would the head gasket affect the idle? Does the gasket leak externally? My truck won't idle a lick when it warms up. Plenty of power but no idle. Just started one day on the hwy. Only went about 20 miles or so

ChefYota4x4

iTrader: (5)

I actually, not only documented this in my build and troubleshooting threads, but I also dealt with it 3 TIMES, within 4 months, hahaha.

1st time it was just as Bo found, *Coolant Temp. Sensor*

2nd time it was my TPS, as mine was adjusted improperly on the IDL-E2 Settings

3rd time was my IACV(After trying 3 used ones, cleaning mine, ....I got 30% off Dealer OEM unit and voila, once again the surging went away.)

Technically, there was a 4th time, I guess you could say, ....it was related to something unique. MOST early gen EFI vehicles have a fuel cut that works off the brake pedal. Because of my Crappy CAM(since replaced with 261), I had a HELL of a time diagnosing my erratic idle issues, etc. It would always want to idle low, so I'd have to adjust it up at the Idle/Air screw. Eventually, even when warm, I would have it idling up too high and so, when I'd come to a light, any stop, ....If the idle was above 1000rpm, when I hit the brake, the idle would surge up and down, around 1000 down to 550, then back up, then back down, until I could get it to idle down below 1000rpm.

A lil more description of EXACTLY the RPM is, might help as well.. Is it consistently going up and down to a specific point, each time.....Or is it SURGING and HOLDING? Sorry if I missed that, lol.