Irregular Boost readings

[AndrewRe]

Hi all,
1st post in here as just bought an NT a couple of weeks ago.
Made a handful of improvements in readiness for a tune, so not certain if the issue I am seeing has always been there or it is an outcome of the work done.
In short;
HPD frontmount intercooler
Manifold & Swirl valve clean.(Wasn't too bad for 200k)
EGR Block
Catch Can
Swirl butterflies removed but vac left connected.
Fuel Pre-Filter
Boost Guage (Hooked up to vac line leaving throttle housing)
EGT Guage (Cant connect till exhaust arrives)

As with before this work, it goes really well. Pulls well, but you can feel a variation in engine note.
Now I have a boost guage, I can see it is all over the place.
30 Second video below, pulling up a hill with constant throttle.
I am open to your advice and appreciate it. Thanks

https://youtu.be/EhBOI2pzys0

[old Jack]

Hi Andrew,

I notice the check engine light is ON, this may or may not be contributing to your problem. it would be interesting to know what codes are stored in relation to the CEL.

When you had everything apart were all the vac hoses checked for internal blockages?
Are all the vac hoses a tight vacuum tight fit?
Are any of the vacuum lines soft when you give them a squeeze check along the whole length of the hose, could they be collapsing internally under vacuum pressure?
Vac hose is cheap so it may pay just to replace it all with new hose.
Are all vac hoses connected correctly?

Does your NT has a VGT or waste gate control of the turbo?
Have you checked the boost control actuator?

You say the test was done with constant throttle but the tacho shows the rpm fluctuating around the time of the major boost fluctuations.

Have you done a full throttle, held in same gear, hard acceleration boost check?
what is the max boost pressure?

OJ.

[AndrewRe]

Thanks

Thanks OJ,
Wow, heaps to look into there.
I had already organised to pick up a scanguage this morning so will check codes tonight. I had assumed it was to do with blocked EGR, as that has been the case on other vehicles.
I will also pick up a few meters of silicone vac tube and replace it all when I get home tonight.
Turbo appears to be a VGT but not sure how to check the function of that.
The rev changes would be mainly just gear changes, I think.
You have given me lots to start with so I will do what I can tonight, and come back.
Your experience is appreciated. I owe you a beer

[old Jack]

Hi Andrew,

Forgot to ask if you have manual or auto trans?

My understanding of the function of the swirls valves was improve air passage through the inlet manifold at below 3,000 rpm. I think swirl control valves were not fitted to the NW's and not sure if and what other differences there are on the inside of the inlet manifold.

Here is link to online the Workshop Manual, it takes a while to get used to the menu system and sometimes info is hard to find but with practice and exploring you should be able to find the info you need to assist you, if not shout out.

http://faq.out-club.ru/download/pajero_iv/maintenance/Service_Manual_2008_2013/2010/index_M1.htm

OJ.

[AndrewRe]

Hi again OJ,
Thanks heaps for your help and the link to the manual.
Picked up a scan guage today, and had MAF, MAP and EGR codes.
I cleared them and voila! fixed!
It must have been from when I first started after manifold clean. As soon as codes cleared it is now boosting evenly.
It is very different to any that I am used to.
My son's Patrol, gets up to full boost and pretty well just stays there. Right the way through power and rev range. 20psi constant using a dawes valve.
This is set up very different and most driving is done at 3-5 psi and peaks at 15-18.
Anyway, a lot more stable thanks.
I'm booked in for a tune next week so it will change again.
Spoke to my tuner and he said don't bother with dawes valve control. The Pajero is more than capable of controlling boost for itself and hence a better outcome.
Thanks a lot
Andrew

[AndrewRe]

Hi Andrew,



Forgot to ask if you have manual or auto trans?



My understanding of the function of the swirls valves was improve air passage through the inlet manifold at below 3,000 rpm. I think swirl control valves were not fitted to the NW's and not sure if and what other differences there are on the inside of the inlet manifold.



Here is link to online the Workshop Manual, it takes a while to get used to the menu system and sometimes info is hard to find but with practice and exploring you should be able to find the info you need to assist you, if not shout out.

http://faq.out-club.ru/download/pajero_iv/maintenance/Service_Manual_2008_2013/2010/index_M1.htm

OJ.

It has taken 6 months but.... Alas, Boost fluctuations fixed. I installed tillix control. Great Boost control but no effect on Boost flashing between 5 and 30psi as I come off high boost. I was laid in bed and suddenly got an idea. Couldn't sleep as mind buzzing so got up and googled the purpose of the throttle. Turns out there is 2 purposes. 1 to speed shut down and 2 to choke off a little to encourage EGR into manifold. Whenever I came off a higher level of Boost it would choke off a little. Because EGR has been moded a dramatic loss of manifold pressure would occur, causing the throttle to snap open again, where it would immediately close off again. This may occur 5 times a second and I was concerned for the welfare of my turbo.
Long and short... At 3.00 am in the morning I removed my throttle flap. Had the most satisfying test drive at 4.00 am. EGTs are now rediculously low. Can't get as high as 400c. Stops fine so very happy to at last.

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[Allan2]

Your are not worried about "run away diesel' problems which could be controlled by the butterfly. I have a 1/2" hole drilled in mine.
Allan.

[AndrewRe]

Thanks for your comment. It snuffs very quickly so it isn't an issue. If something occurred I could cover the snorkel to choke it. The Turbo seems to be in good cond and never need to top up oil between changes. Got 50ml of oil out of the catch can on last change. So fuelling run-on isn't an issue.
The hammering my turbo was getting due to the ram effect-hammer was a much greater concern. Also it goes better and EGTs down heaps.

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