G'day to all,
I recently bought a TS V6 manual wagon and have been fixing all the little things that are not quite right.
My thanks to all who contribute, your help has been invaluable so far.
But I can't find an answer to my current challenge. Hoping you can help me out again.
When the car is first started, it revs to 2200 rpm.
It slows down as the water temp rises, so I reckon the temp sensor is ok, but I don't like it reving so hard with no oil in the rocker gear.

The temp sensor resistance cold is around 2K ohms.
If I unplug the connector from the temp sensor and install a 1K ohm resistor, although a bit difficult to start, the revs are acceptable,
around 12 to 1300 rpm.

Could the fault be the stepper motor, or dirty throttle body?
Any / all comments are welcome

Regards,
Terry

hey Terry could be time to clean the throttle body as well as the ICS although it sounds like the TPS might be playing up, I think there is way to test them using your multi meter by checking the resistance value, I think there might be something in the sticky about it, also the air temp meter which is just behind the air filter might need a clean, I use electrical contact cleaner on mine and let it dry

Thanks for the reply Chris, when the engine is up to normal operating temp, the idle speed is fine. Does this say the TPS is ok?
Also, when hot, the engine sometimes hunts, just like a diesel. Any clues there for you?

I'll take your advice and check the air temp connector, but I have already cleaned every connector under the bonnet with Innox, which is supposed to be a cleaner and corrosion inhibitor.

Regards,
Terry

clean throttle body
..
yes the idle stepper motor may be the cause $70 plus GST
doesn,t look adjustable -- or repairable

make sure the accelerator cable isnt sticking

TPS can be adjusted

Many thanks magna buff, you seem to be the guru here?
The cable is ok, I've checked that. Not dry, not frayed anywhere.
Mate, I'm an/was an electrical/electronic engineer & technician .... ie capable of most things electric.
Can the stepper motor be dis-assembled? Does this item fail regularly?
I believe the TPS is ok, as it idles just fine most times ... to me the hunting points to the stepper, am I correct?

Chris, cannot fault the connector, it's spotless.

Regards,
Terry

Magna buff, not sure how to reply, but yes, pdf.

Terry I would give the throttle body a good clean off the motor, the stepper motor can be pulled down to an extent and to clean properly you might need to do this, I just did this job on a 4 cylinder auto without any change to it but I didn't strip the stepper motor back just removed it from the TB and gave it clean with some throttle body cleaner and compressed air did the same to the rest of the throttle body, the only way you can rule out the TPS is to put a multi meter on it and check the value from it's closed position to full open position. hope this helps. Just to add I'm a big fan of dielectric grease and use it everything from wire connections to spark plug leads.

Thanks Chris, already decided to clean the throttle body, seems to be the go, it's much discussed on this forum!
I'm thinking that the commutator may be the problem with the stepper motor, possible to clean that?
Trouble is, it may not be able to be pulled apart, as magna buff suggests.
You have to be able to get the thing apart without buggering it up so you can put it back together again!

there are a couple of screws that hold the connector plug to the the ICS if it's a similar set up to the toyota this should be able to be removed allowing you access to the shaft, you will get a lot of carbon build up and gunk under this shaft, might need some pipe cleaners to get in there.

Stepper motor can be dismantled, (doesn't have a commutator or brushes), but doesn't need to be dismantled to check it. It has two centre tapped coils, measuring resistance from the centre tap to the outer two terminals should give 4 identical readings. If one reading shows a different resistance or open circuit, the thing is stuffed.
The nose of the stepper motor moves in and out under ECU control, and controls air flow through the internal passage. Shouldn't gunk up, but worth a look anyway.

Thanks MadMax & Chris,
Went out and metered the TPS, it reads 5.32K overall, 4.65K at idle and 300ohms at full throttle .... seems linear throughout it's range.
Also found the ISC connector, disconnected it, was very dirty! Must have missed it earlier. Dopey me!
Anyway, it's clean now, but will have to wait until morning when the engine is cold to see the result.
Also found the stepper motor in the pdf manual.... it's unlike any other! I'll check it as per your description Max, many thanks for the reply
Regards,
Terry

Another thing I'm unsure of, the gearbox (manual) is very slow, ie can't rush gearchanges.
It's not too bad when cold, but get's worse as the oil temp increases. Is this normal with Mitsubishi?
I've changed the transaxle oil, replaced as per the manual, but given the beast is 20 years old, does it require a thicker oil?
Or are the synchro's suspect? The clutch adjustment is good, I've set it to be off the floor (as it was when I bought the car).
Still have free pedal travel, before you ask!

I appreciate your response, I'm not a dill with cars, but this is the first fwd & Mitsubishi I've ever worked on.

Regards,
Terry

Started it up this morning, stone old, no change.
It still revs to 2200K rpm, rocker gear rattling like mad until the oil gets there.
Even with the air-con on it idles at 1500rpm when hot ....
Not happy Jan!

Am beginning to think I may have made a mistake buying this Mitsubishi, it seems to have stupid engineering problems.

Am beginning to think I may have made a mistake buying this Mitsubishi, it seems to have stupid engineering problems.

It's an old car. Bound to have problems that need sorting. Say no more.

Generic information, but may be useful? (third one down):

http://autorepair.about.com/od/enginetroubleshootin1/a/TS_idle-speed.htm

Check the throttle cable stop screw for incorrect adjustment? Apparently shouldn't need to be adjusted from factory, but may have been moved inadvertently at some point in the past. Correct way to set idle is by shorting the electronic spark advance cut terminal to ground and tweaking the speed adjusting screw on the throttle body.

Pictures missing from thread, but more info here:

http://www.aussiemagna.com/forums/showthread.php?t=36405

And here:

http://www.aussiemagna.com/forums/showthread.php?t=31580

Note in the first thread, post #5, it is mentioned that deterioration of the fast idle air valve (the one that sets idle when engine cold) will result in an un-adjustable idle speed, and the recommendation is that the throttle body be replaced.

If you think you want to try the scattergun approach I have a known-good ECU from a 94 V6 TS Auto (may use the same ECU as your manual?) and a distributor that I bought while trying to diagnose a stalling problem on my car that I could send your way for a nominal fee?

I also found that when I was trying to find info on the net for my car troubles I got more hits when I searched for "6G72 problems" rather than "Mitsubishi Magna TS problems". The 6G72 engine was used in all sorts of cars with various minor changes - Australian Pajero and Triton, Euro Mitsubishi Sigma, Japan/US Mits Diamante, US Dodge Raider...many of the issues may be common to the Magna TS V6.