Intake plenum questions

fishon1213

Observer
I'm in the market for a gen 2 or 2.5 montero and have some questions about the intake plenum/butterfly issues with some of these vehicles. I have done some searching but most info is about how to repair the issue and I have a few more questions.

1. Which engines and years are affected by this? I had never heard of it when I had my gen 2.5, is it just the dohc engines?

2. What are the symptoms of this problem? Misfire, CEL?

3. Could it cause internal damage in some way?

4. Any easy way to look at the plenum and tell if it's been replaced?

5. Anyone have personal opinions about the choice of buying the genuine mitsu plenum, or just removing the butterfly? I also read about using the butterfly assembly from a 3.5 kia plenum which is much cheaper.

Thank you everyone for sharing your knowledge and experience on this forum and others, I can't imagine working on cars without the internet...''i'll just ask the guy at autozone'' lol.

I hope to be back in a monty soon.

Sent from my E6782 using Tapatalk
 

nckwltn

Explorer
1) I believe it is the DOHC motors only. Although the Gen 3, 3.6L has as butterfly as well
2) I also believe that pieces from the butterfly fall down into the cylinder area and cause untold damage to the top of the cylinder and inside of the head.
3) Yes
4) Not sure
5) If it was me, I would want to keep the valve. Changing the length of the intake runners impacts torque and HP at different RPM. Perhaps pulling the intake, taking out the butterfly valve, and using locktite as you put it back together would likely prevent a failure

I'm in the market for a gen 2 or 2.5 montero and have some questions about the intake plenum/butterfly issues with some of these vehicles. I have done some searching but most info is about how to repair the issue and I have a few more questions.

1. Which engines and years are affected by this? I had never heard of it when I had my gen 2.5, is it just the dohc engines?
2. What are the symptoms of this problem? Misfire, CEL?
3. Could it cause internal damage in some way?
4. Any easy way to look at the plenum and tell if it's been replaced?
5. Anyone have personal opinions about the choice of buying the genuine mitsu plenum, or just removing the butterfly? I also read about using the butterfly assembly from a 3.5 kia plenum which is much cheaper.

Thank you everyone for sharing your knowledge and experience on this forum and others, I can't imagine working on cars without the internet...''i'll just ask the guy at autozone'' lol.

I hope to be back in a monty soon.

Sent from my E6782 using Tapatalk
 

rajin cajun

Adventurer
Can't answer your questions directly. But, I have a 1994 SR 3.5 DOHC and it applies to my model and 1995 I just bought the updated plenum when my mechanic was doing the water pump and timing belt. My IAC went bad in 1999. I was able to drive the truck to Stealer. It was a few hundred dollars and no more problems. The updated OEM number (MD335940) is on the plenum if its updated. It is no longer sold by Mitsu.

OEM parts for our rigs are becoming obsolete!


Happy Trails!

RC
 

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