So having tightly refitted MAP with new O Ring and seen DPF drop to 40 odd % (maybe it regened?) I now still have the choking but no engine management light and the underboost code seems to be gone.

Gone back to Forscan for data again for potential issues ahead of choking and checked ranges for various measures.

Thing that appears to be an issue is MAF levels. I read ranges should be up to c8500Hz and mine seems to be hitting that shortly before choking. Also the g/s is hitting c140g/s which I read is very high. See top two lines (red and green) on graph image. Yellow fat lines show choking points.

I read that if demands are beyond these peaks then the fuel air ratio will go out of kilter and either run rich or lean.

Am going to clean MAF today and will consider swapping if not(about the only thing not changed in chasing this problem!)

Does anyone know if very high MAF readings can be result of other upstream issue?

Thanks

 

2 hours ago, lukefjohnson said:

So having tightly refitted MAP with new O Ring and seen DPF drop to 40 odd % (maybe it regened?) I now still have the choking but no engine management light and the underboost code seems to be gone.

Gone back to Forscan for data again for potential issues ahead of choking and checked ranges for various measures.

Thing that appears to be an issue is MAF levels. I read ranges should be up to c8500Hz and mine seems to be hitting that shortly before choking. Also the g/s is hitting c140g/s which I read is very high. See top two lines (red and green) on graph image. Yellow fat lines show choking points.

I read that if demands are beyond these peaks then the fuel air ratio will go out of kilter and either run rich or lean.

Am going to clean MAF today and will consider swapping if not(about the only thing not changed in chasing this problem!)

Does anyone know if very high MAF readings can be result of other upstream issue?

Thanks

 

The MAF reading is a bit higher than I would have expected, maybe there is an Air Leak somewhere between the MAF and the Turbo or the MAF could be reading high.

The good news is that the Turbo is maxing out where I would expect it to.

Thanks Tizer - that gives me hope! will investigate both. Looking at the MAP pressure at 250 I wondered if that showed that things were good as the air arrived at intake however I guess air flow and pressure are different things? 
 

 

Following this with interest (does anyone know the frequency limits that should be seen? My understanding is that it is a hot wire device that the ECU controls at a specific temperature by measuring resistance and adjusting the current accordingly this being calibrated on airflow? 8.5kHz seems very high?)
If you haven't changed that after everything else it may be the way to go but I'd still use one or more of the multiple webpages that show how to test it.
Also testing the turbo vane operation all the way back to the operating valve and the valve itself (plus filter if fitted) can't be a bad thing?

Thanks Shearers - awaiting MAF cleaner arriving any minute! 
good point re researching testing methods.

Ah yes should have mentioned that I changed the boost pressure valve for new yesterday and no change. At only £40 thought I’d gamble but alas not. 
 

hence going back to the data as you’ve suggested before.
 

 

53 minutes ago, lukefjohnson said:

Thanks Tizer - that gives me hope! will investigate both. Looking at the MAP pressure at 250 I wondered if that showed that things were good as the air arrived at intake however I guess air flow and pressure are different things? 
 

 

The MAF and MAP Graphs should look almost exactly the same shape as each other alL the time, air has to be drawn in for it to be compressed by the Turbo.

The Max MAP of somewhere near 250 normally only occurs for a short time under Maximum Load, e.g. accelerating hard going up a hill. If that was not the case when the Screenshot was taken then maybe the Turbo is producing too much Boost when it shouldn't.

Thanks Tizer

MAF and MAP do seem to mirror each other so I assume good and 250kpa on MAP was under Max Load expected as well.

Cleaning MAF has made car a lot more responsive and clean revving allowing me to pull to 70 plus now without issue (was 60 before), but still getting choking shortly after 2500rpm generally. Think the higher speeds are simply due to improved running up to the threshold where I get the problem.

MAF is still high at 140+ g/s peaking at c8500Hz. Am going to check for leaks between intake and turbo as you suggest - could a leak in this section cause these figures? The figures seem to move with load and I have reset the sensor calibration a few times.

 

 

 

I think the 8500 Hz is a Red Herring as it is a frequency?  (could only be relevant for the no of times the sensor is being checked and the supply current adjusted, otherwise meaningless for a mass flow rate?)
If cleaning MAF has helped, clean it again?
You have (at last?) found something that has made a change so either do more of it, or test the sensor as far as possible or (I hesitate to say as I need evidence!) change it after your thorough leak check? 
And still test turbo and possibly go round the testing loop again as there may yet be other problems that have, so far, been masked?

29 minutes ago, lukefjohnson said:

could a leak in this section cause these figures?

Thinking about things, probably not but a leak will upset things.

I still think that if the Turbo is maxing out before it should then that could cause problems although I would expect an Overboost Code.

Thanks both

I did think cleaning the sensor again might be worth while so have done so. Have also bought a second half sensor on ebay for £20 to swap and test at low cost.

The concern I have with the frequency maxing out is that a) the overall value of 150g/s seems high b) watching a video about tuning, a guy suggested that if you're hitting the frequency limit then beyond that the car will run either rich (which it feels like mine is). No idea whether that is right and probably not but just letting you know my (desperate) thinking!

Other minor thing is I did get a longer bolt to replace dodgy short one for EGR exhaust pipe fitment to intake and unfortunately its not much better and pretty much spinning due to cross threading, so this is only really held on by 1 bolt...

Going to try and remove pipe between MAF and Turbo to review but looks a nightmare to access turbo end.

 

11 minutes ago, lukefjohnson said:

the car will run either rich (

Diesels don't have a Mixture that can be Rich in the same way as Petrol's do. 

If too much Fuel is Injected then there will be a lot of Black Smoke coming out of the Exhaust.

Thanks Tizer

So I'm not getting black smoke and just been out in it and as I first suspected, the MAF clean (i did it again) seems to be only making better progress towards point of choke and also got P0299 again.

Will inspect pipes...

 

Duplicate post...see below.

If there's a DPF, working correctly, there shouldn't be any black smoke as exhaust pipe should always be clean based on Jimmy's Finger test?:
https://www.youtube.com/watch?v=o3MlEuicVyk
Can someone please explain this "frequency thing" what it means where it comes from or, actually anything that helps me understand?

 

Hi Shearers 

Will try and dig out video I was watching about maxing out MAF, however after a bad day yesterday (I pulled intake to turbo pipe and all looked good). I have woken up determined to get intake manifold off to find throttle butterfly. Car runs great low down and issue builds with load and 6 garages have not fixed so it must be something niche. 

I was flying on dual carriageway when original issue happened (injector seal) so my brain has come up with a story (overnight!)that the throttle flap let go at speed, jammed ahead of one of intake ports and it is not letting it get enough air into one cylinder under load that leads it to get out of kilter with others and ultimately faulter.

I was wanting to avoid taking intake off to get a good look as I’m total amateur forced to take care of back because garages couldn’t sort.

if the flap wasn’t downstream of throttle it MUST be upstream somewhere which ain’t great whichever way (I just didn’t build confidence in garage who mentioned it in off hand way after saying I needed a new turbo (3rd time after rebuilds).

anyway going to look to pull intake back just enough to get endoscope in now!
 

 

 

I'm reminded of something like: when you've removed everything else and are left with one factor, however unlikely it needs looking into - was it Sherlock Holmes or something?
I still can't understand why the garage that found the flap missing wasn't more concerned as (presumably?) it must have been fitted from new although how it came off is also a mystery.
I don't know the size and how far up (drawn by the airflow) it could possibly go if that's what has happened?
I really hope you find something.
 

2 hours ago, lukefjohnson said:

to get intake manifold off to find throttle butterfly

It may have been removed by a previous owner because it was sticking.

So I'm half way there removing and just need 5 star torx (coming tomorrow) to complete. Not confident as can now get endoscope quite a way in but can only see huges amounts of gunk.

I fear your point Tizers might be true - I've owned the car since 2.5 years old, so not before my time, but I wonder if one of the garages its been to over time have removed?

And like you say Shearer's, it a process of elimination and it will be another potential suspect removed plus a clean intake at the very least (plus learning a lot...)

Will let you know.

So removed intake and no butterfly inside.

Hugely gunked up intake however (cyl 1 and 4 particularly) and maybe they all look like this after 95k of mainly short journeys (7-8 miles)?

At least can clean it down and put back together with new gaskets. Another thing off list.

I also now have a second hand MAF to test when i have reassembled intake, throttle, fuel filters etc (no small task!)

Am enjoying learning more but would dearly like to resolve...

My thoughts are also going back to injector that originally got replaced after seal went, but an expensive (at £200) option after I'd spent that last summer on the one in it. (Reminder - I broke leak off connector on the original when changing seal)

 

So cleaned intake manifold and ports up and reassembled.

Same issue (expected) exists.

DPF expert looking at exhaust back stuff on Thursday. 

 

Also just checked replacement injector number (bought for £200 from reputable motor factors back last year)

It has the same reference on the front panel - 9687454380, however on the reverse is has 0986435 434 as opposed to 0445115 087 that appears on all the others (understandably) and most of those on Ebay. 

Now most sites seem to imply that these are completed interchangeable, however I am now wondering. Have ordered another cheap one off Ebay but with like for like rear code...

 

Sorry, in most ways, you didn't find something and still have the problem.

Looks like you are pursuing the injector issue and perhaps separately, the DPF investigation.

At least you have a sparkly inlet manifold etc.

Thanks for coming back with Chapter whatever we are up to!

Yeah appreciate your guys support because I love the car and just want it sorted however am kind of on my own save leaving it with garages whose enthusiasm wanes the minute the first couple of attempts to fix didnt resolve!

And I wanted to build my skills aged 51 and feels like I am learning a bit.

That said I just want it fixed!!

Will see what these two routes offer...

So DPF guy has reviewed in detail. He did a smoke test and MAP sensor still had small leak, however he thinks larger leak towards back of engine - needs going on ramp to identify location.

As you suggested Tizer he seems to think air leak seems most likely although did also mention about deliminating pipes that look fine outside but closing under load inside. 

Needs oil change badly (as he flagged) and MOT is due to run out (it was done just before problem reared its head so 12 months!) so might get garage to do both and check for leaks at back of engine. 

Still cant believe that all other garages who've looked at it have recommended all these other changes before double checking this first however we will see....

 

 

 

Got my own smoke leak detector and DPF guy secured MAP so no leak there but smoke flooding out of what am guessing is a valve on rocker cover?

Guy mentioned rocker cover gasket, however assume that air would still escape from this valve if done?

Help appreciated!

see image below