I can't agree with you on this one. At the very least not go my Montero. On my engine there is a breather hose going from the back of passengers side valve cover to the intake hose between the air filter and throttle body. Not sure what the purpose of it is, since it doesn't have PCV valve on it (it's on a separate hose from driver side cover to plenum), but it does carry some crud to the front of TB. That's why you got to clean TB occasionally.

 

That breather hose is to keep crankcase pressure neutral. I figured that one out by routing it to my catch can, almost couldn't get the oil cap off if the engine was running. However, like you said, it naturally gets crankcase vapors flowing through it which can cause the soot buildup everywhere that we are seeing.

 

Hunter/Naeos........Oooops, you are right......I forgot about that hose that plugs into the large air intake, just in front of the throttle body......so thats the rascal that allows the carbon/crud to flow into our nice, clean throttle body. Ummmmm, maybe just loop it around and back into itself......a big Do-Loop......that will solve the dirt problem.......but I guess lead to other problems. Actually, what technically would happen if that hose is just left to dangle toward the ground and the hole plugged at the air intake? Like in the old days, with those vapors just puffing out the side of the engine, doing no harm to anyone. Trees need that extra carbon monoxide to survive and lead a long healthy life.

 

You'd get a vacuum leak and P0171 System too Lean code on the engine.

 

Hunter.....Looks like that answer came super fast....guess its one of those "been there, done that" situations for you.

 

Thinking about rigging up another catch can of sorts to that breather tube to try and curb the carbon buildup in the TB. Catch cans everywhere! lol

 

Naeos......If you do, post some pics of your contraption.....maybe you can sell a ton of them to all of us....ha ha.

 

Hey Hunter.......I had a few moments and did the tests of my IAC "Idle Air Control" valves as shown in Video No. 2 that you posted above. Results:

The original Mitsubishi IAC: The ohms readings between electrical plug tips 2-1, 5-4, and 6-5 were right on the money......30.8, 30.8, and 30.5 ohms. But there was no reading between 3-2 plug tips of the IAC......so, no resistance at all, so I guess it must have a broken/melted wire and the IAC is "no good".

The 2 Rock Auto "knock off" IACs: The ohms between the tips was right at 40 ohms on all the 4 tests.

My question: Will the higher ohms reading of 40 cause any issues in the performance of the IAC?

I still need to test the Mitsubishi IAC that I "borrowed" from my other Montero. Its still hooked up in the Monty that has been having the Idle issues. Im pretty sure it will test as being good. But Im still back at the Idle issue. Seems strange that the IAC would suddenly fail and also another problem occur at the same time.

 

I just measured one of my spare IAC's I have laying around and the pin readings were 39.2 +/- 0.1 ohms except pins 1-2 which showed 38.9. This is a factory unit that I suspect to have slight idle issues but I haven't tried it in years. The other factory unit I currently have installed that has zero issues shows readings between 41.9 and 42.2 ohms.

Edit:
I just found this neat page after a quick google search. Note that the engine coolant temperature apparently needs to be at or below 68F for this test with normal range being 28~33 Ohms, very interesting.
https://workshop-manuals.com/mitsubi...l_diagnostics/

 

Naeos........Interesting. Your spare IAC had pin readings almost at 40, and you said it was a factory unit......and the other at 41 - 42 ohms is factory. These are "Mitsubishi" brands with the metal body and small "Mitsubishi" stamp on them? I wonder if the broad range of 30 (on my factory IAC) to over 40 ohms (on yours) is all within an acceptable range?

I will try to dig into my shop manual and see if they give the ohms range on the IAC (and I guess my 1994 should be about the same as your model).