OK, I did a lot of reading on here about the IAC which is also called ISC or stepper motor. I am assuming all these names stand for the same thing right?

I think I either have a dirty IAC or a faulty IAC and here is why:

when computer is re-set (i.e. battery was disconnected for long period of time) and vehicle is driven for first few run periods, it has a tendancy to almost stall out after driving and letting off the gas pedal, like at a red light and coming to a stop. Also, when air kicks on, it almost stalls out, but then catches itself and recovers.

to put it simply, the idle is 'lazy' and extremely low in rpm, like about 300 rpm or so, just barely above stalling.

after you drive it a few times, I think the computer 'compensates' for whatever is wrong which I think is the IAC and it starts idling a little better, but is still very low in rpm and idle is still somewhat lazy when air conditioning kicks on.

I think this is why my volts gets so low at idle, the alternator can't maintain correct output at 300-400 rpm. I think rpm should be around double that shouldn't it?

So, I need to know if the IAC should be the first thing I troubleshoot, or could it be something else?

I also would like in depth tips on cleaning the IAC and intake. I hear that carbon build up or residue will prevent IAC from working properly, can someone explain to me how?

I would think that the port is either open or closed or somewhere in between, how would a little carbon affect this function?

what is the important parts that need to be clean? I am going to take it out tomorrow and clean it, I want to know what is important to making it work right. Any possible way for me to identify the difference between just a dirty IAC and a faulty IAC?

Sorry for all the questions, but I need to understand the concept of how this part works in order to properly troubleshoot it and rectify it. Thanks in advance.

Scottie

let it warm up before you drive it, problem should almost go away. If this works replace the idle speed motor.

actually, it idles the lowest when hot.

Remove the IAC & you will find the pintle, the end that does the airflow work, it looks like a flattened cone. Clean it & the port where it goes real good.
Check the resistance on an ohmmeter on the ohmX1 scale

I I I
I I I

is what the pins should look like. Check the upper center to the upper left, then right, do the same with the lowers. I believe the reading is around 28 ohms at each reading.

If all reads well, dissasemble & use 3 in 1 oil to lubricate the inners & reinstall.

Now, if you still have the same issue, it might be the adjustment on the throttle body. It's a screw on the top back on it. You might have a plug sealing it, too.

If that doesn't do it, the FSM states that you need a new throttlebody.

I would try the Seafoam througth a vacuum line also, to clean deposits from the intake manifold that might be clogging miniature airways.

If it all fails, wires, plugs, air filter, air leaks in intake tract, dirty injectors...

Ed

Scottie

Cleaning the IAC/ISC..whatever... clicky HERE

When you remove the IAC check the coil resistances, on my 93 Mk2 3.0 it was 28-33ohm each, but the replacement I got was 40 ohm (nom)

pin-out is
1--2--3
4--5--6

check between 1--2, 2--3, 4--5 & 5--6 you can also check 1--3 & 4--6 should be 56-66ohm.

SteveN <img src="/forums/images/graemlins/wink.gif" alt="" />

Ed, you have faster fingers than me <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" />

Thanks guys, I will see what kind of progress I can make this afternoon.

not sure if this changes anything for me, but I don't have the 3.0L engine, I have the 3.5L SOHC in a 99 Montero.

Scottie, have you checked mitsubishilinks.com for the manuals there? The FSM (for the gen I anyways) does have the testing procedure for it using just an ohm meter. I would imaging the right manual for your model would have the same testing procedure.

IIRC, I used the info in the 96 FSM for when I tested out my 95 (3.0 24V SOHC). Also, as a final verification on mine being bad (the metering said it was), I swapped over from the wife's 98 (3.5 SOHC) and it ran perfectly. Turns out it is the same ISC. So, Scottie, pull the FSM and verify the ohms to what the others are saying, and meter it out.

Mine needed the cleaning routine at first, but that lasted less than a year before it crapped out. Note if you clean to be sure to read the part about not getting carby cleaner to far into the intake plenum.

If you need a new one, RockAuto has them for ~$150. There is a guy out there who also rebuilds them for ~$100. Stealer is $350.

dsmisc.com will sell you a brand new Mitsu one for $131 and change... I'm a satisfied customer <img src="/forums/images/graemlins/kewl.gif" alt="" />

Eric W.

well here is what I did, comments and feedback are welcome:

after taking the air intake hose off the intake, I noticed that the 'flap' and intake was completely black with a thick coat of carbon. then I took the ISC Motor off, and same situation there, thick carbon coating everything.

now can someone tell me why it is bad to spray cleaner in the intake and the hole where the stepper motor goes? I used STP air intake and throttle body cleaner, it says it is safe for all sensors and will not harm. the directions say to spray it in the intake for 6 seconds, then wipe up excess put back together and run it.

so that is what I did, and let me tell you what a world of difference.

b/c the computer was not reset in this process, it was still 'adjusted' to the dirty setup and when I had started it for the first time after cleaning it, it idled very high (1200-1400 rpm) after letting it run for about 15 minutes, the computer started re-adjusting back to a more normal 'running configuration' like it would have if the computer was reset to factory settings like when I had disconnected the battery in the past. had the wife take it for a test drive and she reported that it has a much more dependable idle and when stopping at stop signs and red lights, the idle is strong and higher at about 800-900 rpm.


So, thank you to all that helped, seems like it just needed a good cleaning.

I know it is too late, but would my 'safe for sensors' intake cleaner damage anything if I used it like the instructions said to? I did spray it in there for about 6 seconds or so.