Idle RPM, won't idle when cold

[waiter]

This problem seems to be getting progressivly worst, low idle RPM, would stall when stopped. Last spring, I turned up the idle speed with the idle screw, this helped for a while, but last winter, it was getting real bad, and got to the point I would need to hold the accelerator a little when stopping, or it would stall out.

Seems to be worst when cold. and was also hard starting when cold



I looked at the vacuumn hoses, all look OK, I tested the Throttle Position Sensor today using the test procedure in the manual, the TPS looks OK.

Inspected Intake tubes no cracks or leaks.

I pulled the fuel injectors today, the o-rings were brittle. this may be causing some of this proble. I'm sending them off for cleaning and testing Mr Injector at $16.00 each.

John Mc

88 Dolphin 4 Auto

[Maineah]

John if I remember correctly there is a thermostatic idle control under the rear of the manifold over hang it is has a sliding disk that allows air in dependent on air temp and a electric heater closes it once the key is on.;

[waiter]

I was reading up on that. Idle Air control valve. I'm still trying to sort out what I have.

It seems there are two styles, a mechanical (thermal) that mounts on the bottom of the throttle assy this one has a built in thermostat and it controls the opening based on water temperature (left), and a electrical one thats located below the throttle assembly, but not mounted to it. (right)

It seems both styles have their problems.. I verified I have the electtric style see photos

These two photos came from Yotatech

Reading thru that thread, it appears they are also confused and don't realize there are two different types that they are talking about.

John Mc

88 Dolphin 4 Auto

[5Toyota]

have you checked out the control unit in the top of the air filter box lid.

[waiter]

have you checked out the control unit in the top of the air filter box lid.

The Mass Flow Sensor (MFS) is on top of the air filter box and measures the air flowing into the engine by using a vane.

Mechanically, its OK, not binding and moves freely. I didn't check it electrically, but I have the procedure and will check it next time it gets warm outside.

Electronically, the MFS is similar to the Throttle Position Sensor (TPS),

From the reading I've been doing over the weekend, it appears like the problem is in the Idle Air Control Valve. There seems to be two styles, One is strictly mechanical and is bolted to the bottom of the throttle body assemble (The left photo in the above entry). The mechanical one operates off of coolant water temperature.

On mine, its mechanical and electric, two bolts hold it to the bottom of the intake manifold. (its outlined in red on this photo) The air is controlled by coolant temperature, (more air when cold) but there is also a small electric heater that also controls the air valve via the ECU.

I found this on MarlinCrawler.com (a Toyota specialty site). From reading thru the thread, this is exactly the same symptoms I seem to be having. There is a good writeup for testing the valve..

IDLE AIR CONTROL VALVE

STATUS:

I'm sending the Fuel injectors off today to have them overhauled.

Next warm weather, I'll take the air control valve off and take it apart.

I ordered a valve cover gasket kit and will adjust the valves.

I need to take the EGR valve off and clean it.

John Mc

88 Dolphin 4 Auto

[Maineah]

It has a disk inside that rotates with a slot in it the colder it is the greater the opening I would try some WD40 or the likes on the disk. There is a mounting screw that has Loctite on it, it is slotted it does have some degree of adjustment. I just had a look at the crawler site I had forgotten the Toyota ones came apart I don't think the Bosch ones do so if it is a Bosch (long tube on the end) a bit of WD40 usually frees them up.

[waiter]

STATUS UPDATE

The temperature got up to about 55 today so was able to do some work.

FUEL INJECTORS

I sent the injectors to have them overhauled. They tested them before and after. The "before" spray pattern was fair and flow from all the injectors was within 10% of each other. After they were finished, spray pattern was excellent and flow matched perfectly. They put new filters and o-rings on all the injectors.

I didn''t see anything that I could attribute the bad idle to.

I reinstalled them today.

AUX AIR VALVE

I removed the aux air valve, hoses looked good, I could blow thru the water lines so I know they are not plugged up. I took the cover off and the gate valve moved freely. I cleaned the inside, gate and everything, The electrical connector for the heater seemed corroded, I cleaned it up and used jumper leads to power the heater element. The gate moved slowly as the heater heated the bi-metal strip.

I reassembled and reinstalled the Aux Air valve. I didn't see anything that I could positively say is causing the idle problem.

VALVE ADJUSTMENTS

Adjusting the valves on the 22RE is easy, Although its recommended to do it on a hot engine, the next best thing is doing it cold.

Removing the valve cover can be a problem. Heres what I did, unscrew all the accessory stuff from the cover. Remove the four hold down bolts. The cover probably won't pop off because its being held in place by the hardened rubber washers. The old rubber washers under the hold downs are compressed and hardened into the threads. I used a screw driver and preyed under the washers to get them to loosen a little. I then unscrewed the washers off of the studs.

After the four rubber washers were off, the valve cover just lifted off.

VALVE ADJUSTMENTS = WHAT I FOUND

The intakes were about .005. the exhaust were zero, and were pressing hard against the valve stem, probably took about 1/4 to 1/2 turn of the adjust screw before the rocker was backed off of the valve.

I readjusted the valves to .007 IN and .011 EX.

I suspect the Valve adjustment may have been the idle problem, particularly when cold.

NEXT JOB

Next warm day we get I'll take the EGR and EGR modulator valves off and check it for leaks.

I still need to clean the throttle body, and PCV valves, and then start putting stuff back together.

The only thing I've found so far is the valves way out of adjustment.

JOhn Mc

88 Dolphin 4 Auto

[Derek up North]

Once everything's back together, do you plan to go back and check the valve clearances cold? It would be interesting to see how they change from your 'cold' settings.

[waiter]

Maybe, maybe not. Its a pain in the behind to remove the valve cover. I've been reading up on valve clearance cold vs hot on the toyota sites. better to do it hot, but cold will work. I was somewhat surprised that all the exhaust valves had zero (actually minus). However, I guess the seats and valves wear, so as they wear this reduces the clearance.

JOhn Mc

88 Dolphin 4 Auto

[Derek up North]

Had anyone who set them cold gone back and checked them hot? I guess on the flip side, if someone set them hot, it wouldn't entail much extra work to let it sit until cold and recheck before reinstalling the valve cover!

Anyway, if it turns out that they're way too wide you'll hear it as soon as you start the engine!

[Maineah]

Toyota recommends hot. They will change around .002. Kind of surprised yours tightened up John wonder if someone has been in there before? They generally are wide. To me valve adjustment (with those that don't require dismantling the engine) is part of a tune-up. Tight valve clearance advances valve timing loose ones retard it so it’s kind of important.

[waiter]

I suspect these were never touched since it left the factory. I have a little over 86,000 on the speedo now. I put 30,000 on it since I got it three years ago, and that included almost 15,000 round trip to Alaska.

JOhn Mc

88 Dolphin 4 Auto

[5Toyota]

really never heard of doing that cold . agreeed it is the pits removing the cover hot. i have to do my 4wd again. and it is the pits doing it hot i aways heard the hotter the better . and lose is better then hot at least we dont have to mess with a bunch of shims.

[linda s]

Never heard of one getting tighter. Mine always loosen up so i do it at least every couple of years. I use Ove gloves to get the valve cover off and adjust. Kind of like having cartoon hands but you get used to it and can work faster cause your fingers are not on fire.

Linda S

[Maineah]

The shim clearance 3L had a tendency to tighten up but that was a completely different arrangement usually there are enough moving parts to ware and increase the clearance.

[waiter]

UPDATE

Nice day today, so was able to finish up the job.

EGR VALVE

The EGR had a little carbon, but nothing that would cause the problem. Also checked the modulator, it was OK also.

THROTTLE BODY CLEANED

I cleaned the throttle body and plenum, squirting carb cleaner thru all the passages. I seen a little gunk, but nothing was plugged up. Scrubbed the inside of the throttle body,

REASSEMBLED

I put everything back together, New valve cover and 1/2 moons. Refilled the radiator. When I cranked, It would start, then die. I looked again and found a large hose I didn't have connected.

Restarted, VVRRROOOOMMM.. Had to turn the idle air adjust way down. (This doesn't have an idle stop, it has an aux idle air screw) Nothing is leaking, so took it for a short drive.

No problems, when I stopped at the lights, it didn't stall. After warmup, it was idling a little bit to low so I turned the idle air out about 1/2 turn. It seems like it might have a little more power. I base this on the use of OD. it didn't seem to pop in and out of OD like it used to.

Its running real good. idles OK in gear and out of gear. We have a cold front moving thru tonight so I'll try and do a remote start after it cools down.

In conclusion, I think the problem was the valve adjustment.

JOhn Mc

88 Dolphin 4 AUto

[waiter]

I've put maybe 50 miles on it since all the work. It starts up with the remote starter, idles smooth cold and hot, also idles good with the Air Conditioner running.

At 87,612 miles, the engine is strong and in good shape.

I'm cAlthough all the cleaning and adjusting of the other components adds to the continuing relieability of the engine. I'm 99% convinced that the valves out of adjustments was the caulprit for the rough idle problem, and may have also contributed to what I observe as a declining gas mileage. (When we first got it, averaged around 15, the last trip we took, average was around 13.

We'll be doing a road trip in a couple weeks, I'll report back on the performance and gas mileage.

John Mc

88 Dolphin 4 Auto