Here is a little write up I did a while ago.

Most of the Mitsubishi EFI engines, just like most fuel injected engines, have a problem in regards to oil and sludge build up at the throttle body. This is caused from the breather tube in the induction pipe breathing oily vapour. This will cause a restriction in the air flow through the throttle plate thus less air will get through at idle and the idle speed may drop. In Magnas, both 4cyl and 6cyl this may cause a slightly rough idle. In the initial stages you will not notice as the Idle Speed system should compensate. As the car builds up mileage the problem will get worse as the internals wear and you get more blow by (this is when combustion gasses escape past the piston rings or past valve stem seals and build up pressure in the crankcase.) So how to fix, read below........(this is based on a V6 Magna however most Mitsubishis will be similar)

What you will need:

I am a strong believer that when ever you remove a part that has a gasket it is wise to replace that gasket as it will not compress a second time thus you may not get a good seal.

Gaskets required (this is for the KR/S V6)
1/ Throttle body to inlet manifold
2/ Gasket between air bypass and TB Is a funny shape rubber "O" ring. (this is the bit the coolant pipes connect to)
3/ "O" ring for the ISC Motor
4/ "O" ring for idle speed screw. Mitsubishi do not list them but if you go to Bursons or Repco you will be able to get one the same size.
5/ Vaseline or rubber grease
6/ Carburettor cleaner, Wynns is the best one I know of.
7/ A small artist paintbrush for cleaning galleries, pref one that is horse hair and not painted handle as the carb cleaner will make a mess.



What to do:
Removing the Throttle Body.

Remove the induction pipe, breather pipe and the air filter cover.

Disconnect the throttle cable.Remove the 2 bolts under the rear of the TB from the mounting bracket. (12mm)

With the engine cold, remove then replace the radiator cap to ensure there is no pressure in the cooling system. You will now be able to remove the 2 coolant pipes and if you are careful you should not loose any coolant. You can plug these to stop coolant loss if you wish.

Disconnect the ISC motor wiring and the TPS wiring, be careful not to loose the metal clip that retains the plugs.

Remove the 4 Retaining bolts (12mm)


Dismantling the Throttle Body.
Remove Throttle Position Switch

Remove air control valve (be careful of the screw heads as they are prone to be very tight. If this is a problem tap a hammer on top of the screw driver to help loosen them) You may wish to secure the TB in a vice but be very careful and use some soft pine to insulate it from the vice jaws.

Using 8mm socket, loosen and remove Idle Speed Motor.

Remove Air Screw.

Give throttle body a VERY good clean with carb cleaner paying particular attention to the air bypass passages etc

Give air valve a good clean again paying particular attention to air passages. hint when cleaning through passages a small artists paint brush is ideal. Make sure it is a good one so the carb cleaner does not dissolve it.


Reassembling the Throttle Body.
Reassemble the air valve and isc. I ALWAYS use new "O" rings and gaskets which in total will cost about 20 dollars. You will find if you use the old gasket between the throttle body and air valve will swell being rubber. if this happens and you do not have a new one handy use a tiny bit of Vaseline to hold it in place. Do not use bearing grease as it will damage the rubber.

Refit the TPS. To set the TPS, open the throttle and place a .5mm feeler gauge in the throttle stop. using a multimeter set the TPS so it is "just" open circuit with this minor opening. (pin 1 & 3 on TPS)

Refit throttle body to car, start and warm up. BE SURE THAT THE THROTTLE BODY GASKET IS FITTED THE RIGHT WAY ROUND, THE LITTLE TAB HAS TO BE TO THE REAR ON TOP.


While cleaning disconnect battery. when all has been re assembled hold foot on acc to floor, turn ignition to on without starting and hold here for 30 seconds. this will reset isc motor.


Start car and bring up to operating temp. stop engine and bridge wire in engine bay behind left strut tower, is usually a beige one but check if unsure. this will turn off the isc. Mitsubishi states idle should be 700 in neutral but I have found it is better at around 850. Only use air screw to adjust as the throttle stop screw should never be touched. (hint, on some models this plug is in different places, fine someone who can show you the right plug and ALWAYS us a fused bridge wire)

I hope this is a help. I have done the many many times and in 95 percent of cases the you would never tell the car is running after this has been done

Someone may wish to remove this reply and please make this sticky as i think it will benefit all

Can you be specific about which wire to bridge to turn off the ISC, a photo would be great. I tried to look for it quite some time ago, but couldn't find anything matching your description.
Also how to bridge it. Basically an idiot's guide.

I've seen a 2nd gen on here (pseudomorphis sp.?) who has actually put a little fuel filter in the breather tube i think you called it. He showed me the filter and i was quite surprised how much oily residue there actually was in it!
Would you recommend other do this as well?

man i though this was a simple process.....i was going to give this a shot myself but dismantling all those things isn't my forte, looks like i'll be waiting.

as much of a detailed write up that is, man, i didnt think it would take so much!

I've seen a 2nd gen on here (pseudomorphis sp.?) who has actually put a little fuel filter in the breather tube i think you called it. He showed me the filter and i was quite surprised how much oily residue there actually was in it!
Would you recommend other do this as well?


pretty sure that'd be an oil catch can; just have a go people when you actually try it you see how it works. If possible how to bridge with fused wire would be good. I never used a fuse before. Also will the car continue runnign with isc off?? Then you would be able to set the idle right??

Hey good to see you're still alive Mal ;). Nice article thanks.

I've got an oil catch can on the PCV line, & an inline filter on the breather tube... it really does collect a fair bit of crap.

Mal, is there any other way to set the TPS without a multimeter? coz mines cactus...:cry:

ey phil, when ya come round, lets slap on an oil catch can on my car ;)
and do you know how to clean the TB phil? i got NFi how to...

I've got an oil catch can on the PCV line, & an inline filter on the breather tube... it really does collect a fair bit of crap.

Mal, is there any other way to set the TPS without a multimeter? coz mines cactus...:cry:

Only other way is to get it done or get a new meter

Darn... thanx for the info mate.

TuffTR, no probs mate, the catch can is easy 2 make... Yeh we can clean your TB too but you'll have to leave it on the car, unless you have a multimeter.

i got a multimeter!

all sweet mate, what materials do i need? or have you got some spare bits n pieces...
ill make ya some eyelids, we'll do a swap!:D

Madmagna, is this the "beige wire" in question? (the one with a fuse-like end).
I was toying around with the dash today, and now my ISC isn't working properly, and every time I stop the idle drops and kills the engine. So I'm wanting to set the base idle so I have at least something to fall back on if the ISC has carked it! (Don't know if the ISC has been overworking due to a possible bad base idle?) I've already had one burnt-out ISC about a year ago...

Is it still effective to clean the tb by just disconnection the air filter, opening or pushing forward the butterfly thingy and spraying throttle body cleaner in?

Is it still effective to clean the tb by just disconnection the air filter, opening or pushing forward the butterfly thingy and spraying throttle body cleaner in?

That would be good to know! I realise it wouldn't be as affective as taking the thorough cleaning method, but would it go some way towards cleaning it?

How soon after doing so could you start the engine?...

Bit of a mine there... but a valid question none-the-less.

I did the quick and simple method on a Mitsubishi 2.6 throttle body (same as the 3.0L V6 TBs) and it did help quite a bit. Unfortunately it didn't clean out the galleries that otherwise connect to the Idle Speed Control. Regardless some of the shudder was reduced.

I left the engine for about 10 minutes afterward, then started it up.

What you suggest is what most do with a general service and while is good to do as preventitive work will not clean out anytihng more than around the throttle plate.

It can help on one that is maintained though

Can petrol, turps, or kerosene be used instead of carby cleaner?

Refit the TPS. To set the TPS, open the throttle and place a .5mm feeler gauge in the throttle stop. using a multimeter set the TPS so it is "just" open circuit with this minor opening. (pin 1 & 3 on TPS)



While cleaning disconnect battery. when all has been re assembled hold foot on acc to floor, turn ignition to on without starting and hold here for 30 seconds. this will reset isc motor.


Start car and bring up to operating temp. stop engine and bridge wire in engine bay behind left strut tower, is usually a beige one but check if unsure. this will turn off the isc. Mitsubishi states idle should be 700 in neutral but I have found it is better at around 850. Only use air screw to adjust as the throttle stop screw should never be touched. (hint, on some models this plug is in different places, fine someone who can show you the right plug and ALWAYS us a fused bridge wire)

I hope this is a help. I have done the many many times and in 95 percent of cases the you would never tell the car is running after this has been done[/QUOTE]

I have just taken off TB and cleaned it, and also replaces spark plugs, leads and all filters on my TE. However now its idling at 2000rpm but drops down to normal when in Drive or Reverse. I wanna know how i do the procedures above with the feeler gauge and stuff. Im not sure what it means. I hope i havent stuffed a sensor or something.

ive lost power to my isc motor has any one had this problem before?

Just thought I'd let people know that I did the clean today and got completely buggered up by Mitsubishi not having the appropriate gaskets for the air bypass or the throttle position sensor. The latter the guy said are no longer available or being made, and the former are never kept in stock (take two days to come from Sydney) but they had two at Knox (they didn't have any when I drove there, "computer lied"). Since I had the thing already disassembled and cleaned, I tried in vain to get the old one to fit again: Leaked like a sieve. Was really in a pickle at this stage and ended up getting a second hand throttle body for $22 at the wrecker.
So my advice would be to get the gaskets before you start. I laughed when I walked past the Mits sign that said they sell the best backed cars! I know second gens are getting on a bit now, but there are so many of them around that they could be supported a little better.
When I get the gasket, at least I'll be putting it on a pristine backup TB.
Mike

I have a rough idle prob with the TS, if the throttle body needs a clean how much do you think a mech will charge...It may not be the pob as the car will pop and burble at the lights but as soon as I drive off all is fine? Sooo.. me thinks.. plugs?? Any ideas.

how exactly do you disconect the throttle cable? do you undo any bolts or does it slide out of the thing its held in ive been trying to get it off for ages its pissing me off can anyone help?

Bumping this topic as I am interested in it.

Has anyone done Madmagna's procedure lately? .
If so where did you buy the new gaskets / O rings that are needed.

Here is a little write up I did a while ago....

I hope this is a help. I have done the many many times and in 95 percent of cases the you would never tell the car is running after this has been done

The above quote is the last line of Madmagna's opening post. Maybe I'm thick but I don't quite understand it. Does he mean that the car is quieter and smoother?

Of course - after cleaning its so quiet you won't even know that the car is running!
Its a bit of an embellishment on that the car will now run as intended.

Now where do you get the gaskets/O-rings (not stocked by local mitsu!).

The odd shaped expanding gasket: What I did was carefully measure the lengths of its parts and made a minimum number of cuts and trimmed off about half a mm here and there until all was right lengths. Then I put a thin bead of silicon in the depressions the gasket rests in and lay the pieces down, further trimming as necessary. There is then enough silicon here and there to smooth it into any gaps and the gasket material stays put. I joined it all together and half a year later it is holding fine. I couldn't see any other way. It didn't take all that long after studying it and working out where to cut. Anyway it worked.

The main gasket was easy to deal with again using silicon. I first tried to build it up with layers of paint. I've since done it without paint and just used silicon straight away. No probs.

I used clear silastic.

It would be good to know where to get unused gaskets though.

O-ring for the ISC should be a standard replacement from anywhere that sells O-rings provided you know the right size.

Throttle body cleaning procedure in the manual is actually quite specific about not bothering to clean the bypass passages. Even says to plug the entrances with a couple of small rags to prevent any solvent entering inside and damaging the ISC or fast idle air valve.

My gut feel is that most mechanics will only clean the throttle body while still attached to the engine. Unless there's something seriously wrong with it that warrants its removal, or there's a problem accessing it while bolted on, they'll probably leave it in place to clean. If you pull off the intake hose there is enough room inside the V6 engine bay to clean the throttle without having to remove it completely . If you can get the ISC out and a replacement O-ring for it you could probably achieve 90% of the cleaning that's described on the first page of this thread while the throttle is bolted up, and not worry too much about sourcing the replacement gaskets for the throttle and fast idle air valve.

@ac1176
Luckily my v6 is still running smoothly and so I will leave well enough alone.
But its always good to be aware of issues associated with these sorts of DYI jobs.

On the other hand my TP may well need a throttle body and ISC clean.

This is the gasket I refer to. As you can see it has expanded and will not fit back in where it should.

http://i27.photobucket.com/albums/c168/yanndee/IMG_1661_zpse2j1do94.jpg

If, like me, you cannot find a replacement: I found that if you trim the lengths of it by cutting it with a sharp blade and seating pieces back on a thin bead of silicon and use excess silicon to seal cuts it will hold when put back together.

If anyone knows where to get a replacement (preferably of a material that doesn't expand in contact with whatever makes these expand. fumes?) please tell.

Yikes!

That picture tells a thousand words.
I will think hard and long before separating those 2 parts.

Trimming the lenghts to shrink it back to size was inventive.

Might put a catch can on my V6 to keep the throttle body clean.

This is the gasket I refer to. As you can see it has expanded and will not fit back in where it should.

If, like me, you cannot find a replacement: I found that if you trim the lengths of it by cutting it with a sharp blade and seating pieces back on a thin bead of silicon and use excess silicon to seal cuts it will hold when put back together.

If anyone knows where to get a replacement (preferably of a material that doesn't expand in contact with whatever makes these expand. fumes?) please tell.

Good work but was it worth the effort? Did it run any better after the cleanup?

interesting question. It depends entirely on perspective.

For me, everything I do is worth it for the lesson it gives me. In this instance I learnt how to get by without a replacement gasket using readily available materials.

This was part of a complete dissasembly of the throttle body/plenum. I only hedged at desoldering electrical parts. I now have the confidence to rebuild again. That, to me, is 'worth it'.

As I rebuilt entirely a throttle body/plenum and replaced, adjusted, cleaned, repaired the lot, I don't know which particular part or set of parts led to the definite improvement I experienced when I bolted it back on the engine. Or rather, I got the combo from one of my wrecks, rebuilt that and then swapped that with the one on the engine. The engine was better for it. I can only say that rebulding that particular part did not make anything worse. I learnt something there, so any way I look at it, yes, it was worth it, to me.

As the whole thing only cost me part of a tube of silicon and I didn't have to buy a replacement throttle body because I couldn't fix the gasket I suppose financially it's a moot question.

Perhaps even by doing it and making people hesitate at undertaking something as a consequence unless feeling totally sure about it is a good thing so perhaps it was worth it to others also. Whether it's worth it for someone else to do, I cannot say. At least knowing what to expect can be good. I didn't. Doesn't always stop me. Good?, bad?...I don't know. Works for me though.

This appears to be a mirror of http://www.madmagna.com/tech/tbody.htm but without the pictures.

@ CCCMikey
Are you just pointing out that pictures may be had in the mirror?

The OP of this thread and that mirror article are both by MadMagna.
This thread provides for discussion by AMC forum participants on that procedure.
Particularly of interest is the gasket issue that will have to be resolved in some way.