abecedarian

fixed your numbers. 1) Don't know what the mechanic would do to the ECM / ECU- there is nothing adjustable about it. This makes me question your mechanic's abilities and honesty- not saying he's necessarily a bad person, just maybe doesn't know and is making things up.
The only 'adjusments' one may have to make to the engine's systems are the idle speed, throttle position sensor, timing and spark-plug gap... and maybe the a/c idle speed. Even the throttle position sensor should only need adjusted when replaced.
2) Presumably he did this by blocking the vacuum line.
3) 900 is a bit high- spec is 750 with a warmed up engine. Cold idle can be as high as 1200.
4) Cleaning the intake manifold is not a bad idea but may not help.
5) Running a fuel system cleaner may or may not help, but it won't hurt.

A few things-
-- The base engine idle speed is set with the large flat-head screw on top of the throttle body. It should always be set in conjunction with the ignition timing since either one being incorrect will affect the other. Also, with the a/c off and engine warmed up since the idle should be slightly higher when cold than when warmed up. Both of my 22re's idle cold at around 1100-1200 and drop to 750-800 once warmed up.

-- Cold idle speed is controlled by an air valve beneath the throttle body. On the 89, it should be heated by engine coolant. The valve should be open when cold, allowing air around the throttle plate for a higher cold idle, and closed when the engine is warmed up. If it is stuck or coolant is not reaching it, that will affect idle speed in ways that are difficult to diagnose including higher idle speed when hot than when cold.
This is not an absolute way to check the air valve, but if you screw the idle screw on top of the throttle body all the way in with the engine warmed up, the engine should die. If it doesn't, there's a good chance the air valve is stuck open, letting air through and affecting the idle.

-- Coolant temperature is important for the ECU to operate properly. If the thermostat is sticking or is rated too low, it could cause the engine to take longer than necessary to warm up, and this will cause the ECU to not be able to correctly control the fuel mixture and as a result can affect idle speed and quality.

-- The idle speed with the a/c on should not be much if any different than off. It is adjusted with the white plastic screw on the side of the throttle body.

-- There's information that relates that if the idle speed is too high, the ECU will not fire the injectors when the brake pedal is pressed in order to assist in engine braking. I cannot verify this but it comes from 4Crawler so I'll assume it to be true. If the brake booster has in fact been checked and is operating properly, the next time you get surging when pressing the brakes, disconnect the plug from the brake switch under the dash and see if it surges when you press the brake pedal down. If it doesn't, I think you can say the idle is too high. If it does then it's back to square one and looking at the booster. (Don't forget to plug the switch back in.)

I'll add more if I think of anything else.

Bako88

I just want to say - my idle screw has both adjusted in and out after driving and running RPM's up above 4500. I had to get out and open it back up because it kept dying. I figure vibration causes this.

The O-ring wears down, hardens and doesn't hold it in place. Your problem may not have been that in the beginning, but now that someone has molested every part of your EFI, who knows what's really wrong.

I plan to replace O-ring soon.

BTW - I have a 22RE in an 88 4WD Pickup.

stepside trd

You might want to check the harness (plug) going into your volume air flow meter or some folks call it a mass air flow meter. The problems you describe sound exactly like the ones I was exp. and it turns out there was a loose wire in the plug itself. It was hard to diagnose and to find because it is covered with a rubber boot. Vibrations made the contact arc, causing the idle to freak out! Roll back the rubber boot and check the wires going into the plug, takes all but 10 min. I also read somewhere that a cracked distributor will also have the same symptoms, but I have never encountered that problem (not the cap, the actual distributor).

stepside trd

One more thing, push the wires (individually) into the plug until you hear a snap, that is how you know the wires are secured into the plug. Just my two cents, good luck!

dennisw511

I had the same issue. Pull the cap off the DASH POT SUB-ASSY (FOR THROTTLE BODY) be careful not to break. There is a small air filter. Try and clean or get a small filter that they the use in the old cars for air cleaners. Can't remember the name of the crankcase filters. I cut mine to size and the problem was fixed. Toyota want $80 dollars since they don't sale the filter.