Overboost issue P0234

[manrajf]

Hi I have a 2009 triton uk spec with the 2.5 engine, I have a ralliart chip, 2.5" ss exhaust, evo 9 inter cooler, egr blanked, and the catalytic converter has been removed.

Recently while driving on the motorway at around 70mph the eml comes up and the scan gauge shows the code as p0234, it came up 3 times yesterday and then didn't appear again. Could anyone help me with what the issue could be and how I could fix it and is it doing any harm to the truck by me clearing it and continuing to drive the truck.

I have done the search but couldn't find anything that could give me a solution, but it did say that having the bigger zorst could be doing it

Thanks
Raj

[Cowboy Dave]

Try a search on 'Dawes valve'. If I recall correctly Tony's post about those valves was about fixing that code.

[mattz]

Try this link.
viewtopic.php?t=12233

[borngeek]

If I am not mistaken... Raj has a ML. So it is a 2.5 with a normal turbo, not VGT.

Are you running a boost controller, Raj?
What is your max boost on your scan tool? If it touches 22psi it will code.

If not, likely just a malfunctioning MAP sensor.
A Mits dealer can check and replace.
You should get it looked at, rather than continuously resetting the code.

[Tony]

If your logging fault P0234, I think you may have the linear waste gate turbo and not the high power variable geometry turbo? I'm not upto speed with all the UK spec L200's back in 2009.

So assuming the above, If it was running fine with the current mods up until now, something has changed. I'd be looking at the waste gate actuator (make sure the hose is still fitted, check the actator for leaks and make sure the actuator arm is not seized and is still connected. Also check the MAP sensor (Boost sensor) isn't partially blocked and is working as should.
If you have a manual boost controller fitted, back it off to around 20psi if you dont have a voltage clamp fitted to the MAP sensor output.
If you indeed have the VGT getup as in the 2.5 high power, follow the link Mattz posted. I see a lot of this up my way.
Fuelling, free flow exhaust, EGR blanking etc can cause turbo overshoot. Very problematic with electronic boost control systems as the software is too slow to catch it.

I'm happy to walk you though the issues either way.

Can you see how many studs are around the turbo flange at the back of the snail bit where the dump pipe fits on? This will identify what turbo you have.

Cheers T

[manrajf]

Thanks for all your help on this, iv taken a few pics of my turbo hopefully this should help.

I reckon its the 2.5" exhaust thats done it as that was the latest mod, but i dont want to take it off as the truck has never been this responsive.

If I am not mistaken... Raj has a ML. So it is a 2.5 with a normal turbo, not VGT.

Are you running a boost controller, Raj?
What is your max boost on your scan tool? If it touches 22psi it will code.

If not, likely just a malfunctioning MAP sensor.
A Mits dealer can check and replace.
You should get it looked at, rather than continuously resetting the code.

I dont have a boost controller on it as i have no idea to fit one

Edit*** Took it for a spin but just gently and the boost read 18psi max, couldnt get anymore than that.

When the code came up the first 3 times it was under hard acceleration so im guessing it did go over 22psi without me looking.

[Tony]

Looks like the 1515A029 RHF4 turbocharger, its a waste gate type! Strange looking little creature compared to the TD04 waste gate type most of us are used to.

Can you get hold of boost gauge? Tee it into the MAP sensor line and compare the reading to the scan gauge before we touch anything incase the MAP sensor is telling porkies. (Stuffed)

From here, the waste gate and actuator needs to be looked at. Even with the 2.5" exhaust the boost should still be kept in check as your still running the original aspect ratio on the Turbo charger.
Was the waste gate actuator changed when the evo cooler or exhaust was fitted?

Another possibility, just looking at that dump pipe, If you run into a wall with this issue, I think that flange at the dump pipe could be fouling the waste gate from opening fully? You can check this by dropping the arm out and trying to move it with your fingers. May be easiest to undo the actuator off the compressor housing on this one.

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[manrajf]

Hey Tony

Thanks for the info, il get myself a boost gauge in the next day or so, nothing was changed when i changed the intercooler over.

Also what part do you mean by the dump pipe? I assumed the dump pipe was the pipe going out of the turbo and connecting to the exhaust (where the original catalytic converter was)

[Tony]

My internet is shaped at the moment so I cant post big pictures.

Yes, dump is where the cat was, the flange where the waste gate lives is at the lower section where the four nuts are. It works by releasing some of the hot exhaust gasses away from the turbine wheel when the actuator's forced open by the boost at set target level. Not sure what they were factory, but 18 to 20 psi will be safe with no voltage clamp on the MAP sensor.

[Tony]

Just had a D22 Navara (YD25 engine) dumped here yesterday that was blowing smoke and had the oil light on. (Driven to a standstill)

Blown turbo.

Just ripped it off, is the same turbo as your UK speck 2009 4D56 runs.

I'll post the pics for future reference so you can see what it looks like etc.

The IHI RHF4 Turbo

IHI RHF4.JPG

Untitled.jpg

Untitled2.jpg

The IHI turbo come in many variants with three and four bolt manifold flanges and are common on other makes such as Audi, Nissan, Subaru, Isuzu, opel, VW etc.

[manrajf]

Hahah who would have know hey.... I got my boost gauge today, so will hopefully install it tomorow and report my findings

Just to double check i was going through where to Tee into for the boost gauge and i found this image



The pipe in the above image goes into a metal pipe, the pipe on mine on the other hand goes onto the top of the engine head, do i still tap into it?

Thanks

[Tony]

Anywhere between the barb from the inlet manifold and the MAP sensor (Pictured above) is fine. Closer to the manifold is most accurate for what your after.

Anyone doing this, DO NOT PLUMB A BOOST GAUGE AT THE TURBO COMPRESSOR OR INTERCOOLER CHARGE PIPE on a common rail diesel as the throttle body and IC pressure losses comes into play.

We want to know what the boost is at the intake manifold.

[manrajf]

So the boost gauge is on and its showing a difference of +.5psi then what the scangauge is showing. According to the scangauge the truck brings up the error at 21.3psi (been driving up and down the motorway recording it)

So the big question is what is my next step

[Tony]

OK, that pretty much rules out the MAP sensor (Boost sensor).
Now check the waste gate side on the turbo as it is overboosting.

The pictures above show the waste gate and actuator so you know what your looking at.
1. Check the small boost hose is connected, not kinked, squashed, blocked or damaged in anyway.
2. make sure the arm is attached to the actuator.
3. make sure the wate gate arm isn't seized nor that new exhaust dump pipe fowling the internals as I mentioned earlier.
4. Test the actuator (Can looking thing) for leaks. Do this buy pulling the hose off and suck on it. Your face should now go red as no air comes through.
5. another test is, set an air compressor's regulator at around 20psi (I do this often) and use the air gun to manually pressurise the boost tube going to the actuator, you should see the arm move. If it doesn't, work the pressure up to around 26 psi (no more as we dont want to blow the actuator to bits)

If it refuses to move etc, you have found the issue.

If all above has no findings, take the arm off and tie it fully open. Take it for a drive and if the waste gate if functioning as it should, the vehicle will run like a dog and not make much boost, If the original issue still occurs, take the dump pipe off and have a good look at the way it fits behind the waste gate its self. (I'm still very sus of that dump you have as the lower flange may be too close to the internal gate)

Good luck! Has to be one of the above so you will find it in time.

[manrajf]

Thanks Tony, The dump pipe has been on the truck for over a year though, but il still check it just in case there is a soot build up or something (im really hoping its this) only new bit is the exhaust connecting to it at the bottom.

I will try the other stuff you have mentioned (once the bloody rain stops here) and hopefully come to a resolution, il keep you updated

[manrajf]

So since the installation of the boost gauge the issue has gone away and the max boost I can get now is 18psi

[Tony]

fixed it self. 18 is the right boost in stock form.

I wonder if the hose to the actuator was the issue?

[manrajf]

No idea what happened all I did was add the T piece and drove it around and it hasn't overboosted

[Tony]

All fixed for the price of a boost gauge. Must have had crud in the hose or near a fitting restricting the pressure going to the actuator. Now you have a boost gauge, stick a manual boost controller on and work towards 21psi.

[manrajf]

Manual boost controller? Please tell me more