I found a leaking spot after the MAF. I didn't see this leak until I inserted a rag into the air intake duct. It's leaking pretty good volume from the spot my light is on...looks from a metal gasket seal to the intake manifold. That fitting's arm goes to the "Actuator" that's above/to the right (the bell shaped thing). It has something to do with a fuel operation. Do you know what that does and if that could cause it to not start at all and have hard starts, particularly when very cold? I really want to find out what is causing those random and inconvenient no-starts that can last for days and weeks.

It's the Variable Induction Control Actuator. There is a metal shaft connected to the bottom end of it and it inserts into the intake manifold with pivoting hardware by 2 bolts and a there is a metal gasket between it and manifold. It's leaking there. Would this leak cause a no-start though? A small vacuum leak there? Doesn't seem likely, does it?

And / or would it cause the P0171 lean code, only on Bank 1? I'd think it would cause it in both because it's in the middle of both banks and does something with tuning the fuel mixture.

Actually my other 2003 Montero Limited is also leaking at the same place! Lol. It has not done the no-start or hard start thing though. Doesn't make sense...might not be the issue of no-start. But both have lean conditions so that would effect air-fuel mixing eh?

 

So I spent a whole fresh can of carb cleaner soaking that spot I found to a have a smoke leak yesterday.
​​​​​​Here are results with Montero cold idle, hot idle, and hot at 2500rpm. It shows how much it dropped RPM. This was done 3 or more times each setting to verify.

COLD idle: 1400RPM down to 1200 when soaked with carb cleaner for 3 seconds. When dabbing it on it would change it by 50 - 75 RPM.
HOT at idle: 700 RPM to 600 when spraying it 3 seconds.
HOT at 2500 RPM: 2500 RPM to 2250 when sprayed for 3 seconds.

Do ya think this would create hard and no-start conditions though? If cold outdoors and the vacuum was lost because of the leak what would that part's function cause for a cold motor that's otherwise good? The fact I don't have both banks showing "lean" is surprising, unless that air being induced from leak is minimal.

Also, the P0171 code has not come back so far since I cleared it 4-5 days ago. Even after all this spraying, it didn't alert the computer. No "pending" ones either.

 

That looks like the butterfly valve control? I don't have those on my 3.5L. You might have a leak at the spot where the shaft is going through the intake manifold housing or right where intake manifold mates to the part below. In any case, that leak could easily result in lean condition only on Bank 1. Roughly speaking, right up to this point, any vacuum leak would affect both banks, but at this spot air starts to split left and right into separate intake channels for each cylinder. Tbe spot closest to the ftont goes to cylinder #1 (passenger side), lots of unmetered air going there would show up as Bank 1 lean.

You'll need to pull intake and check your gasket. Perhaps it is damaged. If the leak is at the butterfly valve shaft, perhaps it needs new o-ring or gasket of some sort there.

You mentioned a smoke machine. Try that and see where exactly smoke comes out.

Can it cause or add to cold start problems? It can. Can I guarantee that it is 100% the cause of it? No I can't.

 

That's right! Duh! I've removed those butterflies in both of mine! How didn't I put that together?!? Lol

I'm going to cut that shaft off near the spot where it's mounted to the intake and glob a bunch of sealant around it and let it dry. I'll seal it up on the inside the next time I take that beast off...I hate taking that intake off if not necessary... it's a half day affair. I should have sealed those up when I removed them. Both of my Gen 3 had ingested a broken butterfly, but amazingly didn't get ruined. They're lodged in my catalytic converters, or melted I supposed. I'm convinced that's why so few Gen3 Monteros survive past 150k miles. I prefer the 3.0 and 3.5 motors...the 3.0 seem to be the best... they're slow and lethargic but last long time!

My other 2003 Montero has the same slight leak but has lean code for Bank 2. That could simply be electronics that are correcting it and be weaker on other bank though. If I remember right there isn't a hole on the back side of the motor intake, only the front.

 

You don't need to cut the shaft. Just disconnect the vacuum feed to the control valve and or remove control valve all together. Make sure to plug the end of the vacuum hose with a small screw. Then apply sealant on the outside of the butterfly shaft. Disconnecting control valve will prevent shaft from rotating and breaking your sealant blob.