Hey. I am a newbie to your forum, which looks great from the trawling I have done so far.

Got a '94 TS Magna Executive 4 cylinder 2.6 EFI just coming up for 100,000Km - not used much! It has suddently developed a problem where it won't idle when hot. It's OK cold and the revs go up a bit when you first start it - cold. Found some info about the ISC and checked the resistance of the 4 coils which were all around 30 ohms (apparently what they should be) I didn't test the motor with a 6 volt battery as suggested because I wasn't sure which pins to use for the ground connection. Also tried getting someone to turn on the aircon while I listened to the ISC and I did hear some noise, but it was cold, so probably needed to try that when it's hot, but that's difficult, cause it won't idle then anyway!

I was thinking maybe a vacuum leak develops when it warms up, but maybe the ISC, since I see that is a common problem. Does anyone know how to test it further. The 6 volt test method I found was not actually for a Mitsubishi, so I was a bit hesitant to try it anyway. Also I couldn't see any numbering on the pins of the ISC connection.

Out of interest it does have a bit of a misfire under power around 2000 revs (from memory) at times, and sometimes does miss just a tad on idel. Tried injector cleaner once (that may have helped a little - but not difinitive) and just whacked another bottle in recently.

PS. I pulled the PCV valve and that seems fine. Ball rattles and ther is good air flow in one direction only.

injector cleaner bottled shit is good if you put one in per month for 12 months, equivalent to a professional job. Can't help elsewhere sorry

You have 6 wires on the ISC. 2 are red, these are your positive pins. The others are green with stripes and all your earth's for the coils. (if thats helps)

It takes me about 10 mins to change an ISC maximum, I'd go wreckers and grab a few ISC's and pop one in, see what happens. most of the idle problems ive seen in mitbu's are all down to the idle motor.

injector cleaner bottled shit is good if you put one in per month for 12 months, equivalent to a professional job. Can't help elsewhere sorry

Sorry but you could not be further from the truth if you tried

Most of the bottle crap is just that, crap. Is a good suppliment when doing a proper injector clean to remove moisture etc but that is about where it all ends

As for no idle when warm, could be either ISC or even just a very dirty TB, if you have a dirty idle air curcuit then you will get idle when cold off the fast idle system, once the air control valve closes up then you will get stalling

;1211297']You have 6 wires on the ISC. 2 are red, these are your positive pins. The others are green with stripes and all your earth's for the coils. (if thats helps)

It takes me about 10 mins to change an ISC maximum, I'd go wreckers and grab a few ISC's and pop one in, see what happens. most of the idle problems ive seen in mitbu's are all down to the idle motor.

Am I correct in thinking it is a 6 volt motor on the ISC?

dont have my haynes here but im sure its a 12volt system. I'll have to confirm and update this though, may i ask why you say its 6v?
http://www.stealth316.com/2-isc-iac.htm
read that (i am currently) thats the best site so far for most mitubishi diagnostic stuff i need, mainly 3000GT stuff but eh

;1211514']dont have my haynes here but im sure its a 12volt system. I'll have to confirm and update this though, may i ask why you say its 6v?
http://www.stealth316.com/2-isc-iac.htm
read that (i am currently) thats the best site so far for most mitubishi diagnostic stuff i need, mainly 3000GT stuff but eh

I found an article on the net about how to test an ISC (but it wasn't for a Mitsubishi) It said to test the coils with a multimeter which I did and they were all about 30 ohms which was what the article said they should be. It also said to test operation and see if there is movement with a 6 volt battery, as a 12 volt would wreck the ISC.

Interesting.

just checked a Diamante wiring diagram i have in PDF format and the power for the ISC motor is tapped off the injector 12v feed. So safe to say its 12v. Also feed the 02 sensor.

Thanks for the link. It's a pretty good article.

Sorry but you could not be further from the truth if you tried

Most of the bottle crap is just that, crap. Is a good suppliment when doing a proper injector clean to remove moisture etc but that is about where it all ends

As for no idle when warm, could be either ISC or even just a very dirty TB, if you have a dirty idle air curcuit then you will get idle when cold off the fast idle system, once the air control valve closes up then you will get stalling

really? thats what I was told... although, Dad told me that, and he isn't the brightest, belives everthing he hears etc.

The obvious thing to me is the distributor cap, if it's cracked it will run fine when cold, once it heats up the cracks open and it will stall, it will also backfire under revs.
Most people buy any old cap for their cars, some mechanics too, for electronic ignition there is no substitute for genuine. kik

P.S a quick test when warm is to spray CRC or WD-40 into the cap and replace it, it should run fine for a few min's then misfire until it stalls again,
if it does this simply replace the cap.

P.S a quick test when warm is to spray CRC or WD-40 into the cap and replace it, it should run fine for a few min's then misfire until it stalls again,
if it does this simply replace the cap.

Cheers for that, I will give it a try. Strange thing this afternoon when I came home it started idling properly again. Who knows what it will do tomorrow? I am starting to lean towards the ISC being dodgy.

Is there any harm in adjusting the throttle stop a little higher until I resolve the problem? I know it is not meant to be fiddled with and I have read how to set it, but I have to go up to the city soon, and the old left foot on the brake, right foot holding on a few revs could be a problem in heavy traffic.

if it help do it, just remember how many turns out it was.

I had this problem, all you got to do is clean your throttle body out this seem to fix my problem.

I haven't had time to try to fix this yet, but now it has started idling too fast. I think this points to an ISC problem. I am going to pull the ISC and give it a good clean with carby cleaner. Any problems with this?

Nope, I'd just replace it with another unit from a TJ+ onwards, Wont cost you much but you'll know you have a newer unit.

;1218126']Nope, I'd just replace it with another unit from a TJ+ onwards, Wont cost you much but you'll know you have a newer unit.

I gather there is no difference in spec then with the newer models? I thought a new unit was about $200. If I get one from a wrecker, there is a good chance that will fail too, don't you think?

Busselton Misubishi just quoted me $341 for the ISC. I think I will try a clean first!

Of course there is, but for $200 you could BUY a whole 2nd gen. I had a small collection I sent to a member a little while back as i collect them now and again. They always go...

of course there is that chance, Take a multimeter and do a resistance test on the ones you pull out. There were two TW's at the wreckers today and chances are they wouldnt be buggered.

Also check eBay for the ISC - they certainly don't go for that much! I'd test yours with 6V. At 30 ohms this gives a current of .2 amp, should be enough to move it as it has a ball bearing in it, and is not likely to cook the wiring.
I've got one here with a stuffed coil, just waiting to get my hands on a similar broken one and swap good coils into one. The 2 coils are identical.

MITSUBISHI HYUNDAI 3L IDLE SPEED/STEPPER MOTOR MD614380, $110 on eBay currently, $9 postage.
MITSUBISHI 2L & 2.6L IDLE SPEED/STEPPER MOTOR MD614368 Same $
Both "buy it now" prices

I pulled the ISC today, opened it up and gave it a good clean with carby cleaner, but it had no effect after I put it back together. I have tested the coils previously and they were all in spec. Am I right that the ISC is basically an electro magnet? I might pull it out again and test with 6 volts. I assume it should pull in when I put current across a coil? It takes a fair bit of force to push the ISC in to itself and I am wondering if this is normal - seems like it would need a strong magnetic field to move it? I don't think the pins are numbered, which ones should I put the 6 volts across?

I see the ISCs on eBay, and if I can verify mine is the problem, I will get one there i think.

The pins are numbered. I have just wired one into an aftermarket ECU and yes they are numbered.
your middle pins are earth's and do not matter.
Top row, to the left, is 1. (middle 2) and top row, to the right is 3
Then obviously;
Bottom row left 4, Middle earth 5, bottom right 6

I tried making mine move across a 12v battery and I did not have any luck.
I would just try another ISC from the wreckers (newer 3rd gen if possible)

;1224811']The pins are numbered. I have just wired one into an aftermarket ECU and yes they are numbered.
your middle pins are earth's and do not matter.
Top row, to the left, is 1. (middle 2) and top row, to the right is 3
Then obviously;
Bottom row left 4, Middle earth 5, bottom right 6

I tried making mine move across a 12v battery and I did not have any luck.
I would just try another ISC from the wreckers (newer 3rd gen if possible)

So which pins do you put power across?

SHIT
SORRY.
I'm wrong.
Sorry.
MIDDLE Pins are POWER and your end coils are EARTHS. you put 12v in the middle pins (2 and 5) and EARTH the other pins.
In what exact order you need to earth them i have no idea.
I've tried earthing them separately, then 1 and 3 together, no give. Turns out the ISC had just extended too far, so I just found another ISC and she worked fine (orginal one I had wouldnt FIT inside the TB)

Sorry for the mix up.

just testing isc now. using 6 volts, positive on 2 and 5, negative on 3 and 6. There is a very slight movement noticeable when i do this. I thought it would move more noticeably. Any ideas?

Use 12 volt it normal run off 12 volt so giving it half voltage won't do much.

Here is the article I used as my reference, it seems pretty accurate and says don't use 12 volts.

http://dmtalon.v8eaters.com/ISC.html

PS. I am thinking that the ISC is OK, since I did get some vibration.

More in depth ISC description
http://www.stealth316.com/2-isc-iac.htm

The ISC power is tapped off the injector 12v line, So 12v is fine!
28-33ohm for older model (Silver/Beige)
40ohm for newer model (all black)

just testing isc now. using 6 volts, positive on 2 and 5, negative on 3 and 6. There is a very slight movement noticeable when i do this. I thought it would move more noticeably. Any ideas?

ISC motor is a stepper motor. A constant current will only move it slightly. To make it turn fully in or out, you need to pulse voltage onto the 2 coils in a certain pattern, only the ECU can do that. Hook it up to the plug, but out of the throttle body, and switch ignition on and off. Should get noticeable movement, if not, it is stuffed!

Because it usually gets only short voltage pulses on the coils, a constant 12 volts on it may overheat it. Very fine wire in there!

ISC motor is a stepper motor. A constant current will only move it slightly. To make it turn fully in or out, you need to pulse voltage onto the 2 coils in a certain pattern, only the ECU can do that. Hook it up to the plug, but out of the throttle body, and switch ignition on and off. Should get noticeable movement, if not, it is stuffed!

Because it usually gets only short voltage pulses on the coils, a constant 12 volts on it may overheat it. Very fine wire in there!

OK, I hooked up the ISC and turned the ignition on and off and it moved in and out. I reinstalled it and now the car is idling OK. Yesterday when I reinstalled it after cleaning it, it would not idle at all. It seems there is an intermittent problem. (Initially it would idle cold, but not hot, at one stage it idled too fast all the time)? When i was testing the 4 ISC coils, a couple of them showed open circuit at first, but when I moved the contacts from the multimeter around a bit I got the 30 ohms. I figured that I was just not making good contact with the ISC pins, but maybe there is a broken wire in a coil that sometimes makes a circuit and sometimes breaks. Do you think this is a possibility?

Why dont you try another ISC from the wreckers mate?

OK, I hooked up the ISC and turned the ignition on and off and it moved in and out. I reinstalled it and now the car is idling OK. Yesterday when I reinstalled it after cleaning it, it would not idle at all. It seems there is an intermittent problem. (Initially it would idle cold, but not hot, at one stage it idled too fast all the time)? When i was testing the 4 ISC coils, a couple of them showed open circuit at first, but when I moved the contacts from the multimeter around a bit I got the 30 ohms. I figured that I was just not making good contact with the ISC pins, but maybe there is a broken wire in a coil that sometimes makes a circuit and sometimes breaks. Do you think this is a possibility?

Yep! Now that its ok, don't touch it, but get a spare from the wreckers anyway, just to be sure.

Got an ISC from another 2.6 Magna at the wreckers for $20. Supposedly the car was driven in, so ISC should be a good one. Swapped it over and the car won't idle!!! One thing I did was to clean the outside of the wreckers ISC with carb cleaner. Later I read on the (Nulon) carb cleaner that it should not be used on ISC, but I can't see it being a problem? Where to go now??? I read that other things to check could be computer or airflow meter. Also EGR and FIAV (whatever that is).

Any tips on checking these. Where is the EGR valve?

Here's something interesting. Swapped back to my original ISC, since it looks a lot newer and cleaner than the one from the wreckers. Started up and would not idle as with the other ISC. Funny thing tho, I switched the air con on and off, and then my idle speed came good (about 1000 RPM which is pretty normal on cold engine i think).

Does this point to anything?

Air con makes the car idle better because im not sure exactly, puts load on somewhere, my idle is stuffed and having the air con on helps. I havent had a chance to test my isc or anything though.

You should try and get your hands on the black idle motor which is the "newer" type (should test at 40ohms per coil) which personally there should be less chance of being a dud.

With a new ISC the computer may need to "learn?" anyone confirm that? I just clean the idle motors with degreaser and works a treat. They may also be at a different "step" to what you need. Remember the "O" ring aswell.

take tuffys advice and get a 3rd gen ISC stick it in your pocket lol

(I don't condone or recommened theft)

ECU needs to learn how to coordinate the engine revs and ISC motor. Takes a couple of minutes. Replaced a dead ISC on my 2.6 with a brand new one and it took a while, but finally settled down and did the right thing.

ECU needs to learn how to coordinate the engine revs and ISC motor. Takes a couple of minutes. Replaced a dead ISC on my 2.6 with a brand new one and it took a while, but finally settled down and did the right thing.

OK. Cheers for that, I might swap them back again and give it a chance.

try 10 mins letting it idle, or a soft 10 minute drive

I know it's been a while. After the ISC swap didn't fix the problem, I just turned the idle screw up a bit and everything has been fine. Then the idle speed started getting faster, so I backed the screw off to where it was originally. The idle speed was still a bit fast. Now it idles aproaching 2000RPM which is way too fast! The idle scew is as far out as it can go. I have now disconnected the plug to the ISC in the hope that that might help, but still way high idle??? I will mention a few other problems I am having now in case they are related...
1. Radiator keeps blowing out into overflow bottle which fills and overflows too, so that I have to keep topping up the radiator. Temp gauge doesn't show hot when driving tho? Maybe the fast idle is causing overheating? Got new radiator cap which I am about to try.
2. Auto transmission has got quite clunky when it changes gears (especially down shifting).

OK here's the latest update. I sussed out the radiator problem. There is a leak in the plastic section where the radiator overflow hose goes into the expansion tank, hence the expelled water is never sucked back in. I think it may be blowing out excessive water because of the fast idle causing a bit of overheating, since the radiator fans are regularly cutting in at idle. The transmission is probably due for a fluid change although I haven't checked the maintenace schedule yet. The fluid level looks good.

One question - If the ISC is disconnected, what could be causing the fast idle?

PS. I tried with the ISC from the wrecker and gave it plenty of time to "learn" but it made no difference. Maybe I should still try an ISC of a newer model as suggested?