Fixing the overboost issues with the MN 2.5HP

[Cowboy Dave]

gee my triton spikes to like 27-29psi all the times and the engine never cracks the shits... pulls it back pretty fast to 20ish... wonder if id be able to get away with a 3" dumpie and no upset ecu?

I reckon the key word there is "spikes". As I understand it there is a fixed period of time that the ECU looks for before it loses its bottle. There are posts (probably in this thread actually) that mention a specific number of seconds from memory and say that if you feather the throttle so that there is no constant value then you can drive around the problem.

That said, Coughy is correct. 3" would be asking for trouble.

[coughy]

that said dave i have stock and problems lol
my car is SPECIAL as tony puts it

[Cowboy Dave]

Was it special when you bought it or have you "enhanced" it?

[ag9111]

Sure your 27-29 psi is not just gauge over run?

[coughy]

Was it special when you bought it or have you "enhanced" it?

yes very special
was like it before i bought the lemon was
probably why i got it at a great price with low miles on it
was a older couple owned it for towing
i see why they got rid of it
it has 62000kms on the clock after 6 years so it is doing not to bad in that department
but in the special side it is a BITCH

[scumbag]

gee my triton spikes to like 27-29psi all the times and the engine never cracks the shits... pulls it back pretty fast to 20ish... wonder if id be able to get away with a 3" dumpie and no upset ecu?

I reckon the key word there is "spikes". As I understand it there is a fixed period of time that the ECU looks for before it loses its bottle. There are posts (probably in this thread actually) that mention a specific number of seconds from memory and say that if you feather the throttle so that there is no constant value then you can drive around the problem.

That said, Coughy is correct. 3" would be asking for trouble.

yeah its a spike, its got a black one chip and no rear muffler just a sidepipe.
doesnt hang around at 27+psi for very long, wish it did!

[glenfrog71]

I've had these issues since new mitsubishi cant fix it

[coughy]

we all have m8
im getting closer to fixing it lol more testing on weekend

[spriteah]

Hi all. Ive posted this here so as not to start another thread and think my answers might be above.

I have a MY14 MN 2.5 DID. 40K on it. Recently fitted a Spider Box to fuel rail. Same one I had on my Pajero. Told by manufacture it should work. Set on nearly lowest levels I get significant power increase BUT, I also get times when I hear a tappety sound followed by heaps of smoke and reduced power.

I have started to watch ECU data with Bluetooth DBS2 module (what a little ripper). Looks like when I get into trouble the Fuel Pressure is up around 22000PSI then it immediately gets restricted to around 7500psi for a few minutes. I am watching my EGT temps and they are staying under 600c. I see no lights on the dash.

What is going on? Is it spiking turbo boost to alarm? Im not seeing that, boost is around the 23 mark but it always occurs when I am giving plenty of throttle and sometimes initiated when Auto changes gear so it could be turbo over spins? Is the reduced pressure on fuel LIMP Mode (even though I see no dash indications)?

I checked for errors on ECU and non where listed. Any help greatly appreciated.

Spriteah.

[Stoneman]

Hi all. Ive posted this here so as not to start another thread and think my answers might be above.

I have a MY14 MN 2.5 DID. 40K on it. Recently fitted a Spider Box to fuel rail. Same one I had on my Pajero. Told by manufacture it should work. Set on nearly lowest levels I get significant power increase BUT, I also get times when I hear a tappety sound followed by heaps of smoke and reduced power.

I have started to watch ECU data with Bluetooth DBS2 module (what a little ripper). Looks like when I get into trouble the Fuel Pressure is up around 22000PSI then it immediately gets restricted to around 7500psi for a few minutes. I am watching my EGT temps and they are staying under 600c. I see no lights on the dash.

What is going on? Is it spiking turbo boost to alarm? Im not seeing that, boost is around the 23 mark but it always occurs when I am giving plenty of throttle and sometimes initiated when Auto changes gear so it could be turbo over spins? Is the reduced pressure on fuel LIMP Mode (even though I see no dash indications)?

I checked for errors on ECU and non where listed. Any help greatly appreciated.

Spriteah.

Sounds like the fuel limiter is giving in

Probably pushing to much fuel at a guess

[coughy]

that is what i was thiking u need a tony upspec limiter as mine was doing the same now tony has worked his magic and it doesnt do it any more ....

[biggibbo]

Could also be the MAP sensor.

[coughy]

no biggibbo he has 23psi boost and it dies
it feels like it is running out of fuel like a car mine done same

[Earthmover]

Worst thing I ever did to the MN was put a 3" exhaust on it, even with a cat and muffler it would overboost

[biggibbo]

no biggibbo he has 23psi boost and it dies
it feels like it is running out of fuel like a car mine done same

Yeh I get that, but it can cause the issues he is describing.

I have the billet fuel limiter (so couldn't be that), and was seeing the same thing. Black smoke, lots of boost on the boost gauge, but dropping fuel pressure and losing power, wouldn't rev past 3200 rpm in 3rd and 4th. Was not getting any CEL's and had me and Tony stumped. Ended up yanking the MAP sensor, and Bingo - was back to normal.

The map sensor controls your AFR's so if it is dodgy, it does strange things.

[coughy]

yer i relpaced mine as well for different reasons

[kxboss]

SO guys if i want to upgrade exhaust what do i go to?

Stock motor and pipes no chip

just want better power was told go pipes first.

thanks

[Jacobie]

SO guys if i want to upgrade exhaust what do i go to?

Stock motor and pipes no chip

just want better power was told go pipes first.

thanks

I hear the 3" with cat no muffler don't have problems. I've only heard problems with 3" straight troughs myself.

[Cowboy Dave]

It depends what you mean by "first". If you mean in preparation for doing other things like a remap or chip then sure go pipes. If you mean the exhaust should be the first performance upgrade anyone does and that you think it will bring a noticeable difference in power on its own then I think you might be disappointed.

[Earthmover]

SO guys if i want to upgrade exhaust what do i go to?

Stock motor and pipes no chip

just want better power was told go pipes first.

thanks

I hear the 3" with cat no muffler don't have problems. I've only heard problems with 3" straight troughs myself.

I've got a Scotts Rods 3" with 200 cel Cat and a muffler on an MN and it over boosts, very dangerous when you are overtaking with a line of cars behind you and no where to go when it goes into limp mode! I was going to rip the lot out and put the stock exhaust back in but I've traded it on an MQ.
I also found there was more turbo lag with the 3" dump pipe, maybe it was just my imagination?

[PhillipJ]

My 2009 MN has an Outlaw 3" with cat and muffler and it's never gone into limp for any reason other than the hose between the manifold and MAP coming off (i.e. under-boost). I've run an OBDII scanner a few times and seen boost up to 25 PSI. It's not particularly loud so perhaps the muffler is restricting it quite a lot.

[Cowboy Dave]

It typically needs a fixed set of circumstances to provoke it. Usually a good long hill, a decent whack of acceleration, constant throttle (if you vary this you can avoid the issue) and a particular period of time - which I can't remember but will probably have been published in this thread before.

As has been observed a 3 inch exhaust will make it much more likely to occur.

Just because it hasn't happened yet doesn't mean your setup is immune from it necessarily, it may just be that you haven't yet encountered the correct set of variables to trigger it.

[Stoneman]

I've never had an over boost either

No Dawes no chip ATM just the 3" exhaust. Been this way for months now

I carry loads in all sorts of conditions and never had a problem

Touch wood

[coughy]

well well well
looks like i may have fixed the over boost issue i have been having for a very long time
i was towing a van up the cunningham range on week end just gone and i DIDNT GET A LIMP
WOOHOO yes i said to my self
but i did notice that the engine temp did get to 111Deg and the trans got to 100deg
while this was happening i noticed i couldnt get anymore than 17psi of boost?? i thought what the hell i dont under stand why this is the case
once the temps cooled down over the range the boost was back to its normal self(ie 26psi) so im thinking that the new mods /change outs have some how been controlled by the temps and the turbo cant boost any more
i dont know but i got up there and no limp so far so happy
more testing but i will be keeping a eye on this one to see if in fact it is gone and my mods worked.
hopefully goes in soon for a dyno and a test and tune and a desoot
so i will be comparing the chip to a remap results will be interesting im thinking
time will tell
my current form alot may already know to a stock form remap goodness

[har05l]

Mine coded again yesterday while towing in the overtaking lane and cars up my rear, I had to make an exit for the shoulder and almost took out alco who lucky for me I was passing. This is by far the most dangerous thing to happen and those that haven't had it and do will be mortified.
I have been able to pulse the throttle and not code but sometimes it just isn't the time and place when you have others about.
If anybody does contemplate upgrading I'd highly recommend keeping the stock exhaust just in case. I'd hate to try explain to an insurance company if ever it caused an accident


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