ran great yesterday. but by the time it was done motor was at running temp. because you set all sensors when at temp. today went to start and it raced to 1600 rpms and went down to 7 or 800 when it hit 180 degrees. and runs great. when you take off it stumbles when cold. running rich.. when at normal running temp it runs great... I DONT GET IT. do you? lol

they almost all high rev to warm the engine and transmission up then idle down. I think it runs rich on purpose to start and keep a cold engine running until it gets to temp.

There are two idle speed controllers in the isc area. One is a thermostate type in the TB that opens pretty quick, and that gives you the initial high idle. The other is the stepper motor electronic one controlled by the ecu. Try resetting the timing for the cold stumble, and check the ecu ect sensor again.

I have set the timing at 5 degrees with the wire on the fire wall grounded. when you take the ground off it goes to around 15 degrees. and thats what the manual says to do. is there something im missing? they all rev to 1500 to warm up? seems tough on a cold motor. are you speeking of the idle on top of the tb on the back side next to the vacuum line that goes to the purge valve?

ok per the manual it say the high idle is set by the water sensor. im idling 1500- 1700 that in the book shows that the water temp is -4 degrees. the water sensor ohms correct. but will be doing that test again since I got a gauge for water now. so I know exactly what the water temp is. so It might be the water temp sensor.

If you are looking at the TB open end from the pass. side fender, the isc is below and to the left of the throttle bore, secured by two bolts and with an electrical connector on the pside end.

I would recheck the tps adjustment, and the basic idle throttle opening setting per the fsm. These are kind of tricky, using drill bits to set the opening to the factory preset, and if that is off, the tps setting will be off, too. Mitsu engines seem to be sensitive to tps setting, and a little off will make for some bad running, but it's usually not just when cold.

My 3.0 12v motor would pop a 1500-1600 idle speed off a cold start after a cold soak, and it was back to 1000ish withing a minute, and to 800 by 5 minutes easy. Mine was to operating temp within 7-10minutes.

Have you checked for any trouble codes? You can do it with a cheap voltmeter or a test light. This will save you changing parts and a lot of fumbling around.

I would sometimes have a small stumble just off idle when very cold, by the engine was usually very smooth off a cold start, and any stumble was gone with a very few minutes. I never remember any rough idle, except when the ecu cts was bad, and then it wouldn't start at all cold unless you "fooled" it into priming itself by a large number of times just barely bumping the starter to get a lot of initial fuel squirts into the intake vavle, and then it would stumble and bumble really bad, taking a ton of nursing the throttle to get it warmed up and smoothed out, like starting a carb motor with a bad choke. What temp thermostat are you running? I had the best luck with a stock mitsu thermostat, and they are not too expensive. Aftermarket t'stats tended to open too quick. Running a lower than stock tstat killed fuel mileage for me, and blackened the plugs with too rich running.

ISC? isent that the IAC what you are talking. to the left of below the bore. using a drill bit? I dont remember reading the. a feeler gage and set the tps to the point of continunity. where is the drill bit used? I have a otc scanner it has no codes. I go to try to use the diagnostic and it shows nothing. and I dont know why!!! but still reads no codes.

iac = isc

In a 92 sohc 12v 3.0, use page 13A-30 of the 92-95fsm, in the engine section, and connect a voltmeter/test light as shown to read the codes. 21 is the ect sensor code. You get a series of voltage pulses, read per the earlier pages of section 13a.

If I remember correctly, you set the basic throttle plate opening (the idle stop screw) using a drill bit, and then use the feeler gauge to set the tps. This is from the 89 manual, and I haven't looked in the 92-95 manual to see if the same procedure is used, but the engines are almost the same.

ok going to do in the morning. still cant find anything with the drill bit so they must have changed that part. thanks

From the 89 fsm:

FIXED SAS ADJUSTMENT
Caution
1. The fixed SAS should not be moved unnecessarily; it
has been precisely adjusted by the manufacturer.
2. If the adjustment for any reason is disturbed, readjust
as follows.
(1) Loosen the tension of the accelerator cable sufficiently.
(2) Loosen the fixed SAS lock nut; then turn the fixed SAS in
the counterclockwise direction until the throttle valve is
completely closed.
(3) Begin tightening the fixed SAS; tighten it to a point 1 1/4 turns beyond the point where there is contact to the
throttle lever (in other words, to the point where the
throttle valve begins to open).
(4) While holding the fixed SAS so that it doesnÆt move,
tighten the lock nut securely.
(5) Adjust the tension of the accelerator cable.
(6) Adjust the idling-position switch and throttle-position
sensor. (Refer to P.14-65.)
(7) Adjust the basic idling speed (SAS).

Damme if I know where I got the drill bit stuff. Senior moment...