IAC and Live Data (1 Viewer)

[Mfb]

I'm trying to diagnose a cold engine low rpm hesitation issue under load (acceleration).

To rule out the IAC, I've completed an ohm test on the IAC pins, they check out fine according to the FSM. I'm not able to remove the IAC at the moment, but I have live from the TOYOBD1 app. I get data from the IAC, starting at 29% when the engine is cold and decreasing to 12% when the engine gets to full operating temp, at which time the hesitation is not noticeable anymore.

Based on the data from the app, would this indicate that the plugger is moving, and would this be a substitute for an IAC volt test to test plugger movement?

 

[jonheld]

I'm trying to diagnose a cold engine low rpm hesitation issue under load (acceleration).

To rule out the IAC, I've completed an ohm test on the IAC pins, they check out fine according to the FSM. I'm not able to remove the IAC at the moment, but I have live from the TOYOBD1 app. I get data from the IAC, starting at 29% when the engine is cold and decreasing to 12% when the engine gets to full operating temp, at which time the hesitation is not noticeable anymore.

Based on the data from the app, would this indicate that the plugger is moving, and would this be a substitute for an IAC volt test to test plugger movement?

1. It would help if we knew what engine you were referring to.
2. The ISC valve is really only in play when the throttle is at idle position. (Idle speed control). Once the throttle position sensor (TPS) is off idle, the ISC is no longer active because air intake is bypassing the valve.

Depending on the model year/motor/mileage/past maintenance it might be prudent to remove, clean, and test the ISC valve as PM.

 

[ZackR]

Sounds like you have a 93/94 FZJ80 and based on the TOYOBD1 readouts it sounds like the IAC is functional. I would still recommend pulling the IAC and cleaning the passage in case its clogged up.

It's a lot easier to remove the IAC when the throttle body is off, and then you can clean it at the same time. The screws can be really tight so it takes some effort so they don't strip. Try tightening them first then loosing to break them free. I also used some penetrating oil.

IAC passage

 

[CharlieS]

And please use a JIS plus bit, not a Phillips screwdriver.