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Legacy777 wrote:the rotor valve IAC valves are ok to clean....or at least they were ok to clean when I did mine. The recipricating valves are probably better off not cleaned....or something...

Are '91 EJ22 (manual tranny) reciprocating valve style IAC's?

Why would you not want to clean this style of IAC? What are the options?

Yes the 91 MT non-turbo has a reciprocating valve.

I've heard some stories they can be a pain to put back together. You could try spraying carb cleaner in there while it's running and see if that helps.

Some say not to clean this style. WHY? Since it is not recommended to clean it, what are the options for helping it work better?

Try cleaning it a Josh says.

To help it work better you need to have it near the centre of it's travel at the ecu's programmed idle speed. If anyone has played with the butterfly adjusting screw, the idle bypass screw on the throttle body(if it has a screw), or the idle control valves solenoid on top of the valve, then they can be at the end of their travel at idle speed and that makes them unresponsive, which causes surge and erratic idle. Only try adjusting it if you have checked everything else first.

The first thing to adjust is the butterfly. The butterfly adjusting screw is only there for one reason... to stop the butterfly digging into the throttle housing when it's shut and possibly wedging shut. The best way to adjust them is with the throttle body off so you can see what is happening but if you just back the screw out till the butterfly touches the wall of the housing(you may need to back off the cable while you do this), then turn the screw back in again till it just starts to open the butterfly. There is no specifications given for the setting but about an eighth of a turn open should be plenty. Less woulld be ok, as long as the butterfly isn't touching and isn't going to touch when the lock-nut gets tightened or the engine warms up.

Next thing if it has it is the solenoid on top of the valve. Set it to the centre of it's travel if the screws have slotted holes.
We will perhaps be adjusting this again later.

Now you need to connect the car to a laptop or scan tool. The ISC valve should have a duty cycle of 40 at idle if everything is correct. By correct I mean the motor is in good mechanical condition, there are no air leaks, the temperature sensor, throttle position sensor, neutral switch are all working properly.

If the duty cycle isn't at 40 or close to it at idle then you need to adjust either the solenoid or the bypass screw on the throttle body. If you have it, it's best to use the bypass screw. If you don't have the bypass screw then you need to use the solenoid. Adjust till the D.C is close to 40 with the motor warm and idling. Once it seems right, rev the motor to approx three thousand revs for about one minute then let it back to idle and recheck the D.C. Repeat the adjustment till you find the best compromise between steady prolonged idle and the idle immediatly after the reving up. Idealy the setting should be the same for both situations.