Gen 3 - p0171 and sometimes p0174 - possible fix

nckwltn

Explorer
After smoke testing my engine, I found a pretty substantial leak from the front of the lower intake plenum, right where the vacuum actuator turns the rod that all the butterfly valves are attached to. I found that squirting some carb cleaner in the area the smoke came from caused the engine to idle poorly for a moment.

Skip to the next day and I have the plenum pulled the BF valves unscrewed and the rod removed.

The seal at the front was hard and brittle, and broke when I pushed on it.... it makes sense that I was getting p0171 bank 1 too lean, because any air that was getting sucked in was going right into cylinder 1.

I ended up taking an o-ring from O'Reilly, coating it with wheel bearing grease a day using it to seal up the butterfly rod. If I wasn't in California I would have just removed the BF valves and sealed the hole up. The size of the ring was approx 9.5mm ID x 14mm OD x 2.3mm thick.

There is no mention of the rod in the FSM and no parts diagram with part numbers.... telling me that this isn't something you can purchase a replacement for.

I ended up greasing the o-ring because it needed to rotate about 45 degrees when the valve actuates. The valves have a lot more resistance than they did, but still move easily.

I shot a couple of quick videos to give an idea of what the part looks like. In total it took me about 4 hours. Much of that was just removal and reinstall of the plenum.

Need to give it some time to know if this will work long term, but seems to have done the trick to get me past smog.


Other post on this same issue, has good photos of the vacuum leak area. I'm guessing this is going to become a common problem for Gen 3s.

https://www2.pajeroclub.com.au/forum/showthread.php?t=54029
 

SirFrancisDrake

2002 Montero Ltd
Thank you for posting this!

I have been getting p0171 w/ p0174 50% of the time, but it would only happen when I would take extremely short trips, for example driving from a store parking lot across the intersection to another store. Upon restart it would throw the codes... I was leaning toward the MAF being the issue. They never popped up otherwise. Gas mileage was never affected so it wasn't an urgent issue.
 

Scissorgrinder

New member
Hey nckwltn,

Thanks for posting this. Just had my Gen 3 smoke tested after getting P0171 for a while and it seems to leak out of the butterfly valve rod as well.

Can you report how your o-ring fix has held up so far?

Also, you said: "If I wasn't in California I would have just removed the BF valves and sealed the hole up". What's the advantage/disadvantage of removing them and why would that be an issue in CA? I'm down here in San Diego...

Thanks a lot for your help!

Cheers
 

nckwltn

Explorer
The butterfly valves help the engine produce better power a low or high rpm.... longer intake runner is better than at one range or rpm and short are better at other rpm. So having the valves is a plus.

When you go to the smog check place, they are going to do a visual inspection, if they see something missing or modified or something, you can fail.

I am happy to report that all has been just fine after this fix, the codes haven't returned.

Sent from my SM-P580 using Tapatalk
 

nckwltn

Explorer
when did you get a Gen 3?
A couple of years ago. Wife drives it. I got it because of the engine similarities with the Gen 2.5, which I know how to wrench on.... and they are pretty cheap.

In retrospect there are quite a bit of differences outside of the engine....


The Gen 2.5 feels less likely to fail from an electrical issue, where as the 3 has more electrical things that can leave you stranded.


Sent from my SM-P580 using Tapatalk
 

Toasty

Looking for that thing i just had in my hand...
I had the same codes but 171 and 174 would hit at the same time, then a no start condition sometimes. Ended up being a fuel pump. Luckily you can change those in 20 minutes on any Montero. I'm starting to regret my Gen 3 purchase due to the massive amount of electrical BS that is at the age of failure. It seems once a month i have to fix something stupid on it. 4 wheeling seems to bring out the worst in it as well.
 

nckwltn

Explorer
I had the same codes but 171 and 174 would hit at the same time, then a no start condition sometimes. Ended up being a fuel pump. Luckily you can change those in 20 minutes on any Montero. I'm starting to regret my Gen 3 purchase due to the massive amount of electrical BS that is at the age of failure. It seems once a month i have to fix something stupid on it. 4 wheeling seems to bring out the worst in it as well.
I kind of feel the same.... But they are cheap, and so far the fixes are cheap-ish too.

I've also replaced the fuel pump in my 03.
 

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