MN 2.5 Triton making 35psi???

[Adstar77]

Ive just installed a 30psi VDO Boost gauge on my 2009 MN 2.5.

First things first, check out the video here (http://youtu.be/G1BocA4pcDw?list=UUOHtl ... 1P46tNDmdw)

So the boost gauge is installed correctly (as we have installed the exact same gauge on an NP pajero) and I used a hole already in the manifold from a recall fix.



Everything is running fine, I doubt the car is over boosting by a good 10psi, if Im going by the 22psi-23psi that everyone seems to be running on here. Maybe I just suck at the forum search tool, but I cannot find anything about anyone running 35psi!

Now to make things even more interesting, we have good friends at a Mitsi dealer here in Adelaide, and asked them what the car (from factory) should be making. They looked it up on their digital service manuals, and it says at 3000rpm at full throttle in 2nd, it should be making 218kPa - 238kPa, when converted, 31.6psi - 34.5psi. Sounds exactly like my car! Ill try getting a screenshot of the manual to show you guys.

So now Im really confused as to what to believe!
Anyone got any ideas?

[PhatVelvet]

I have a 2013 MN, obdII and torque app says mine is around 22psi. 30+ sounds ridiculous...

[Longranger1]

Measurement wasn't from absolute zero. Subtract 100kpa.

[Adstar77]

Measurement wasn't from absolute zero. Subtract 100kpa.

In the Mitsubishi service manual?

What about the guage then?

[variflex]

As longranger has eluded to, this is also taking in to account atmospheric pressure which is approx 14.7 PSi assuming your at sea level, subtract the 14.7 from your 35 and your pretty close to factory spec

[Adstar77]

Ok, so that all makes sense, but what about the gauge? Ive seen people with analogue gauges before (like here http://youtu.be/dIeNgpqTGhU) so there must be a way to get the readout properly, but the pressure should be equal all through the turbo, intercooler and manifold? Where do they pick the boost reference from?

[Octaneruss]

My 2009 MN pushes to 30psi on spike and back to 25psi foot flat but has held 30 on a steep hill, a little worried so I put a dawes valve to help with the boost spike but it is not really reliable as it works sometimes and not others, I lubricated the ball and seat which helped but has since stopped working. My triton is chip it chipped tune 5. The clutch started to slip on the big hill with 30psi up it so it was making numbers , it hasn't slipped since. I think 30 is to high, thoughts?

[MilkmanDan]

Try running it inline with map sensor hose and see what you get, see everyone else runs from this location with the 2.5s so worth a go to diagnose a faulty gauge or indeed an overboost.

[OffRoadDave]

As longranger has eluded to, this is also taking in to account atmospheric pressure which is approx 14.7 PSi assuming your at sea level, subtract the 14.7 from your 35 and your pretty close to factory spec

I'm struggling to get my head around this, isn't the gauge with the engine off at zero psi, and in the video showing 35psi above atmospheric pressure?

[Adstar77]

Try running it inline with map sensor hose and see what you get, see everyone else runs from this location with the 2.5s so worth a go to diagnose a faulty gauge or indeed an overboost.

Can't see why it would be different when its from the same source, but ill give it a shot

I'm struggling to get my head around this, isn't the gauge with the engine off at zero psi, and in the video showing 35psi above atmospheric pressure?

Thats exactly what I was thinking, just couldn't explain it!



Anyway, had a chat with dad. When we installed the EXACT same 30psi VDO gauge on our old NP Pajero, in the same manner, in the same kind of spot on the manifold, it ran at 19-20psi (seeing its a 3.2 I guess the ML tritons would be the similar). The Pajero service manual said around 135kPa and guess what that is in psi??? . . .thats right 19.5psi! So if his car matches the service manual, why wouldn't mine?

So go figure!

[OffRoadDave]

This has been bugging me all day so I had a dig around in the service manual I have and although I'm unsure exactly which variant the MN has, it's showing the Euro5b-high power engine having a boost pressure of 203.1 - 238.6 kPa, which is roughly 30-35 psi, so it's not impossible for the boost pressure to be this high based on the information I have.

[Adstar77]

This has been bugging me all day so I had a dig around in the service manual I have and although I'm unsure exactly which variant the MN has, it's showing the Euro5b-high power engine having a boost pressure of 203.1 - 238.6 kPa, which is roughly 30-35 psi, so it's not impossible for the boost pressure to be this high based on the information I have.

YAY!!! I'm not alone

[Adstar77]

So just got that screenshot.



He's assured me its the 2.5 high power motor, which he also checked IS the one in my car, thanks to my VIN!

Is everyone else running 2wd's?

[Tony]

That's total barometric pressure quoted there, take static air pressure away and be closer to 22 to 25psi for High power.

I'd be questioning that VDO gauge as they normally are calibrated at around zero for seal level.

Use an air compressor with a regulator fitted set at say 25psi then shove a blow gun down that VDO gauge and see what PSI you get.

If close to 25, you have problems as the IHI turbo will not withstand over 30psi for too long and there is always a risk of cracked piston crowns.

Why your Triton does not log P1298 is a mystery to me. Either that gauge is telling porkies or something funny is going on with the MAP sensor not allowing the ECU to see over 3800mv.

Trust me as I tune these things.

[Adstar77]

So your telling me. . . on our old NP pajero, if I take the figure in the service manual, 135kpa (19-20psi) and subtract static air pressure, which seems to be about 14.7psi, I end up with the 3.2 turbo running 5psi???

Ill go past some hardware shops on the way home tonight and ill test the gauge with a regulator, see how that goes!

[RHKTriton]

This seems to all be heading to the land of nonsense.

The boost gauge is going to show what pressure you are raising the air to above atmospheric, if its scale started at zero.

Just consider for a sec that when you pump up your tyres - not set at 34 - 14.7psi. = 19.3. but 34.

If your tyre is lying on the ground with no valve the air inside is already at atmospheric pressure - approx 14 odd psi.

Back to the engine - if your're getting super high boost I'd be checking the MAP and VGT operation.

[MilkmanDan]

Why your Triton does not log P1298 is a mystery to me. Either that gauge is telling porkies or something funny is going on with the MAP sensor not allowing the ECU to see over 3800mv.

Trust me as I tune these things.

Was going to say if the tritons only run a 2bar map sensor than the ecu would throw a code or at worse start melting insides.

[MilkmanDan]

Try running it inline with map sensor hose and see what you get, see everyone else runs from this location with the 2.5s so worth a go to diagnose a faulty gauge or indeed an overboost.

Can't see why it would be different when its from the same source, but ill give it a shot

I was eluding to the point being blocked partially and maybe falsifying the gauge.

Before freaking out about melting internals maybe buy a cheap gauge from supercheap to test with or just try Tonys method

[Adstar77]

Try running it inline with map sensor hose and see what you get, see everyone else runs from this location with the 2.5s so worth a go to diagnose a faulty gauge or indeed an overboost.

Can't see why it would be different when its from the same source, but ill give it a shot

I was eluding to the point being blocked partially and maybe falsifying the gauge.

Before freaking out about melting internals maybe buy a cheap gauge from supercheap to test with or just try Tonys method

Well the manifold was cleaned right out only a few hundred km's along with any pipes, tubes and what ever else is connected, so I doubt anything would be blocked already!

Still driving normally (like it always has since Ive purchased the car) without throwing any codes and still easily hits 35psi when I give it some gas.

Good news is, its going to Mitsubishi on Monday so they will check everything out. They will be able to tell if its over boosting and tell me what the go is with the gauge. I'm sure it can't be an over boost by 13-14 psi!

[Adstar77]

Ok, so just got the car back from Mitsubishi. I mentioned the car making 35psi and . . . they didn't blink an eye. They plugged it into the MUT (Mitsubishi's computer) and nothing was showing a code, everything seemed fine. So, to eliminate something like the ECU ignoring sensors, they reset everything and we went for a spin. Guess what, still making 35psi and no CEL or anything running different! So we went back and talked to the #1 guy at the dealer and he along with other service and salesmen confirmed that my car SHOULD make 35psi!

So where is everyone getting 22 - 23psi??? Is everyones OBDII stuff giving the wrong reading? Surely out of a forum of 16216 members, something like this would have been sorted ages ago! I also don't see why some 19 year old kid from SA can pose such a huge question about our cars!!!

Anyone got anything to say???

[biggibbo]

Mine spikes around 25psi however the obd2 reader shows 21 ish max

Maybe yours is a turbo charged freak

[OffRoadDave]

Mine shows 21 psi 99% of the time on the on the Scangauge, but that doesn't make it correct, it only shows what the ECU tells it.

I have an old VDO boost gauge that I may be able to connect temporarily to see if I am seeing the same difference Adstar, but don't count on it happening any time soon unfortunately, way too busy with work to try it out at the moment.

[Tony]

They are on another planet mate.

Not 35psi at all.

Mut 3 and other scan tools don't factor in static air pressure.

Nor does your VDO guage by souds of it.

You have nothing to worry about.

[hvac guy]

Mine shows 22 psi

[Naff]

Take 14.7 off.