407 no power and black smoke

Nelixuk2003

Hi

here is the story:

I bought the car as a non runner, after towing the vehicle home I put a new battery on it and it started first time!!!! However when driving it had no power under 2500-3000 revs. After a few days of driving it lost all power and would not rev over 2000-2500 rpm, it did not even have enough power to pull away on a fairly flat road, I also got the "anti pollution fault" message.

I plugged the diag machine in (Peugeot Planet) and it informed me that the DPF was blocked. I also suspected the Turbo was at fault, so as money is tight at the moment I replaced the turbo cartridge/CHRA, while I had the car in bits I removed the DPF and gave it a good clean with a pressure washer and Mr Muscle oven cleaner. After putting the car back together it still has no power, still won't rev over 2000 (occasionally revs to 3000-3300 when warm) and lots of black smoke. I managed to get it out of the yard and it won't go over 10mph.

As there is black smoke I am assuming it's air flow related, live data informs me that the air-flow figure is about 20% down on what it should be so I removed all of the Air Flow system including the inlet manifold and thoroly cleaned it all and replaced the rubber seals where it go's into the cam cover.......... started the engine and still the same.

The EGR vavle had been blanked off so I removed the blanking plate but this did nothing to solve the issue, if anything the air flow is registering upto 50% of expected.

Does anyone have ant clues as to what I could try next?

Kind Regards

Nelix

JohnBoy26

1.6 hdi? More than likely that turbo is gone.

Nelixuk2003

Yeah, sorry, I forgot to put the full car details in

It's the 1.6 HDi 55 plate

I have replaced the cartridge in the turbo and carried out the recommended task I.e. Remove sump replace pickup pipe, replace oil pipe and return pipe along with banjo bolt etc so unlikely that it is still the issue.

snaps

To me its sounds like a dead turbo.

What error codes is it throwing up after what you have done so far?

P.S I love the Mr Muscle oven cleaner bit for the DPF!

Nelixuk2003

Hi

No error codes at all even after the turbo cartridge/CHRA was replaced, I have live data at idle and at approx 3000rpm if it would help.

Mr muscle works a treat 😄

Dia1988

Perhaps dirty or faulty injectors or injector deals?

Is there a carbon build up around the injectors?

Nelixuk2003

Dia1988 wrote: »

Perhaps dirty or faulty injectors or injector deals?

Is there a carbon build up around the injectors?

2 injectors were removed after slightly high results from a leak off test, one of them was gone the other was relaxed along with all seals.

umop apisdn

lots of black smoke ? sounds like an injector gone

Row

What's the injector correction values on live data..?
Is the vvt rod on the turbo pulling down when you start the engine..?

ci985

Think lots of black smoke is erg valve

Nelixuk2003

Row wrote: »

What's the injector correction values on live data..?
Is the vvt rod on the turbo pulling down when you start the engine..?

I'll post the Correction values this evening, the vvt rod is moving at startup.

Might whip the other 2 injectors out and get them checked just as a matter of course.

Keep the ideas coming folks and we will get to the bottom of this.

Regards

Nelixuk2003

mullingar

Also post up the dpf differential pressure under load, the dpf could still be 99% blocked

Nelixuk2003

mullingar wrote: »

Also post up the dpf differential pressure under load, the dpf could still be 99% blocked

If I remember correctly, at idle the Differential Pressure (DP) is 0mbar, at 3000rpm it was 8mbar.

I'll confirm those numbers that I seem to remember noting these the last time I looked at the live data.

Nelixuk2003

Injector Flow Correction Data:

At Idle
Measured Injected Flow 7.06 mg/impulse
Cyl 1 Flow Correction 0.08 mg/impulse
Cyl 2 Flow Correction 0.03 mg/impulse
Cyl 3 Flow Correction 0.03 mg/impulse
Cyl 4 Flow Correction -0.02 mg/impulse

At 2000rpm
Measured Injected FLow 10.20 mg/impulse
Cyl 1 Flow Correction 2.29 mg/impulse
Cyl 2 Flow Correction -0.77 mg/impulse
Cyl 3 Flow Correction -0.91 mg/impulse
Cyl 4 Flow Correction -0.44 mg/impulse

I have only just noticed the Inj 1 Valve so that is probably the cause of the smoke, it is also the injector that was replaced, I have checked and it is programmed correctly in PP

I will take the injector back and see what they say.

That possibly solves the excessive black smoke issue, I'm not optimistic that it will solve the boost issue though.

I also don't seem to be able to display Live data in Graph format in PP. Just shows a black screen that says "Please Wait"

Thanks

Nelix

Row

Nelixuk2003 wrote: »

Injector Flow Correction Data:

At Idle
Measured Injected Flow 7.06 mg/impulse
Cyl 1 Flow Correction 0.08 mg/impulse
Cyl 2 Flow Correction 0.03 mg/impulse
Cyl 3 Flow Correction 0.03 mg/impulse
Cyl 4 Flow Correction -0.02 mg/impulse

At 2000rpm
Measured Injected FLow 10.20 mg/impulse
Cyl 1 Flow Correction 2.29 mg/impulse
Cyl 2 Flow Correction -0.77 mg/impulse
Cyl 3 Flow Correction -0.91 mg/impulse
Cyl 4 Flow Correction -0.44 mg/impulse

I have only just noticed the Inj 1 Valve so that is probably the cause of the smoke, it is also the injector that was replaced, I have checked and it is programmed correctly in PP

I will take the injector back and see what they say.

That possibly solves the excessive black smoke issue, I'm not optimistic that it will solve the boost issue though.

I also don't seem to be able to display Live data in Graph format in PP. Just shows a black screen that says "Please Wait"

Thanks

Nelix

No 1 injector does look alittle out alright but nothing major,Its worth getting it checked out tho.
Whats the condition of the Air filter like..?
What mileage is on the engine..?
Have you checked for cracked Turbo/intercooler hoses..?

As for pp2000 certain versions didnt have working graphic parameter measurements....what version are you running..?

Nelixuk2003

PP Version is 23.25

I will get the injector checked just to be sure.

I have checked the pipework and cannot see anything untoward. If I remove the pipe from the top of the intercooler I can feel it blowing when revved, if I remove the bottom pipe and cover it with my hand the pipe sucks in/collapses, I am assuming this is the expected behaviour.

the Air filter is not the cleanest and I will be replacing it in the next day or so along with the fuel filter.

Mileage on the car is 157,400 give or take a few miles, a little high but I have owned Peugeots that are much higher without any problems.

Thanks

Nelix

Nelixuk2003

I have managed to pull the xml file and txt file from PP containing the log data, I will try and get it into Excel and create a graph.

Nelixuk2003

OK, after much manipulation of the data from PP I have managed to format it in such a way that I can get it into Excel and create a graph/Chart. Unfortunately, I can only get 1 Y axis on it at the moment showing rpm, Is it possible to post files/images on this forum.

The data appears to show that there is insufficient boost being measured compares to the reference values, not sure how this can be considering the Turbo has had a new CHRA/Cartridge fitted and has never been driven yet.

Row

Nelixuk2003 wrote: »

OK, after much manipulation of the data from PP I have managed to format it in such a way that I can get it into Excel and create a graph/Chart. Unfortunately, I can only get 1 Y axis on it at the moment showing rpm, Is it possible to post files/images on this forum.

The data appears to show that there is insufficient boost being measured compares to the reference values, not sure how this can be considering the Turbo has had a new CHRA/Cartridge fitted and has never been driven yet.

I have came across a few of these with the same low boost problems but they weren't smokey.
The turbo electrovalves can give trouble on these or there you may have a vac leak somewhere.
Did you adjust the vvt rod on the turbo at any stage..?

mullingar

+1 with that valve, I had an intermittent one, a right pain to trace and no smoke.

@ op, what's your vacuum like? If it's good, I'd try disconnecting the air box and dpf to see if there is any airflow restriction and to see that the turbo is spinning correctly

Nelixuk2003

I have checked all of the vacuum pipes with a vacuum guage and pump and they all seem to be holding vacuum fine, I also checked the Vacuum Solonoid on the back of the engine and that seemed fine too, think I might replace it anyway just to be sure.

The VVT rod has not been adjusted by me at all. However, as I mentioned in the first post, this car was purchased as a non-runner so who knows what the previous owner has done.

If the timing was out would it make it smokey?

Nelixuk2003

mullingar wrote: »

@ op, what's your vacuum like? If it's good, I'd try disconnecting the air box and dpf to see if there is any airflow restriction and to see that the turbo is spinning correctly

Vacuum seems good (see above post).

I have previously removed the CAT and DPF from the turbo manifold and it still won't rev so no restriction in the exhaust/CAT/DPF and I could here the Turbo whistle when it was revved.

mullingar

Nelixuk2003 wrote: »

If the timing was out would it make it smokey?

I would have thought yes.

Its "reasonably" easy to check the timing on them. AFAIK with a 5mm & 8mm drill bit.

Take off the plastic cam cover with a few 7mm screws, then take off the crank/water pump cover - you will need to remove the aux belt/pulley first (18mm bolt AFAIK). Once the crankshaft timing sprocket is exposed put the crank bolt back in and turn engine clockwise until the circular cut out on the crank sprocket wall is pointing at 12 o'clock and there should be a hole in the block for the 5mm bit to fit through all, before you do make sure the cam sprocket timing hole is approx 11 o'clock. If its @ 5 o'clock turn the crank pulley another 180 degrees clockwise. Rotate engine to fit the 5mm bit into the crank pulley and hole in engine block and then fit the 8mm bit into the Cam sprocket timing holes. If the 8mm bit fits straight through to the hole in the block, its timed.

This doesn't check that the diesel pump is timed correctly which is probably hidden behind the engine mount. It also doesn't check the intake cam - there is a chain inside the cam shaft box to connect the exhaust cam to the intake cam. These normally get noisy before they cause trouble.

Nelixuk2003

Thanks, I'll check the timing at the weekend as the weather here is pants at the moment.

I'm pretty sure the timing will be fine as it used to drive fine (minus the low-end boost) and without smoke prior to the DPF blocking, but it's worth checking non the less.

Nelixuk2003

OK, I have not checked the timing but as I mentioned I think this is OK but will check over the weekend just in case.

I have fitted a new Mass Airflow Sensor and a new air filter and things are worse!!!!

I did have a new fuel filter too but when I went to fit it they had supplied the wrong one.

Anyway, once the MAS was fitted when started it ran fine ......... for about 20 seconds, then the revs started dropping to approx 600rpm then up to approx 900rpm constantly then after approx 10 seconds it stalls, after a few restarts it will eventually run with fluctuating revs but does not stall. Will only rev to approx 1500rpm now and still smoking, maybe a little more than before (that might just be me).

I have taken some more live data starting from before I started the engine and got it into Excel again and linked to it below. I did notice that when the car stalled the measured air flow drops to Zero but the air flow setting still registers along with both Turbo measurements. I'm beginning that 'maybe' the previous owner has put a duff map on the ECU........ Don't suppose anyone who can re-map the ECU

"partyknights.org.uk/Random/Peugeot DataWIP (After MAF Sensor).xlsx"

(I can't post with a URL as I am a new member so cut and past the above into your browser and add the H T T P : / / to the beginning).

Here's hoping we can resolve this.

Thanks in advance for ANY and ALL help you people can/have provide/d

Nelixuk2003

OK, I have not checked the timing but as I mentioned I think this is OK but will check over the weekend just in case.

I have fitted a new Mass Airflow Sensor and a new air filter and things are worse!!!!

I did have a new fuel filter too but when I went to fit it they had supplied the wrong one.

Anyway, once the MAS was fitted when started it ran fine ......... for about 20 seconds, then the revs started dropping to approx 600rpm then up to approx 900rpm constantly (best seen towards the end of the graph) then after approx 10 seconds it stalls, after a few restarts it will eventually run with fluctuating revs but does not stall. Will only rev to approx 1500rpm now and still smoking, maybe a little more than before (that might just be me).

I have taken some more live data starting from before I started the engine and got it into Excel again and linked to it below. I did notice that when the car stalled the measured air flow drops to Zero but the air flow setting still registers along with both Turbo measurements. I'm beginning that 'maybe' the previous owner has put a duff map on the ECU........ Don't suppose anyone who can re-map the ECU

"partyknights.org.uk/Random/Peugeot DataWIP (After MAF Sensor).xlsx"

(I can't post with a URL as I am a new member so cut and past the above into your browser and add the H T T P : / / to the beginning).

Here's hoping we can resolve this.

Thanks in advance for ANY and ALL help you people can/have provide/d

Nelixuk2003

OK, I have not checked the timing but as I mentioned I think this is OK but will check over the weekend just in case.

I have fitted a new Mass Airflow Sensor and a new air filter and things are worse!!!!

I did have a new fuel filter too but when I went to fit it they had supplied the wrong one.

Anyway, once the MAS was fitted when started it ran fine ......... for about 20 seconds, then the revs started dropping to approx 600rpm then up to approx 900rpm constantly (best seen towards the end of the graph) then after approx 10 seconds it stalls, after a few restarts it will eventually run with fluctuating revs but does not stall. Will only rev to approx 1500rpm now and still smoking, maybe a little more than before (that might just be me).

One thing I did notice, when the revs get to the 900rpm mark a sound similar to a dump valve can be heard, not nearly as loud, infact it can only just be heard when sitting in the car, after investigating it seems to be coming from the air filter housing area.

I have taken some more live data starting from before I started the engine and got it into Excel again and linked to it below. I did notice that when the car stalled the measured air flow drops to Zero but the air flow setting still registers along with both Turbo measurements. I'm beginning that 'maybe' the previous owner has put a duff map on the ECU........ Don't suppose anyone who can re-map the ECU

"partyknights.org.uk/Random/Peugeot DataWIP (After MAF Sensor).xlsx"

(I can't post with a URL as I am a new member so cut and paste the above into your browser and add the H T T P : / / to the beginning).

Here's hoping we can resolve this.

Thanks in advance for ANY and ALL help you people can/have provide/d

Nelixuk2003

Sorry for the duplicate posts but when I try and edit the post it just posts it as a new reply and I can't delete them ????

martinr5232

I had one like this a couple of years ago almost sure it was an egr valve that sorted it.

Nelixuk2003

OK, So I got the correct Fuel Filter and fitted it, plugged PP in and started logging data before the car was started.

Looking at the data here is the timeline for what happened:

Started car and it was running fine, revved it a few times (12 secs, 20 secs and 30 secs) then it idled fine and the Measured Turbo pressure and Measured Air Flow readings seem to look as I would expect until approx 51 secs when it started fluctuating before stalling (69 secs).

Started it again and just let it idle and stalled again (91 secs). Started it again with the MAF unplugged and it idled fine (100 secs to 114 secs) plugged it back in and after approx 10-15 (132 secs) and it started fluctuating again and stalled a couple of times. Started it again at 157 secs and tickled the accelorator to keep it running, tried revving and it revved once but wouldn't go over 1500rpm and the last 2 tries at revving, took my foot off the accelorator at 217 secs and it ran pants for a while then stalled again.

The File with the graph in can be found here:

ht tp://partyknights.org.uk/Random/Car Data/Peugeot After Fuel Filter.xlsx

(Remove the space in the ht tp bit)

Cheers

Nelixuk2003

I've added measurements for the Turbo Pressure Solonoid to this graph as well but it does not seem to do much.

Row

Are there any faults been logged when it cuts out..?

I wonder if the crankshaft sensor is picking up a the correct rpm's.
Ideally you would need to scope the crankshaft sensor to see how its preforming.

Whats the coolant temp when the engine is cold..?

Does it run better when hot/cold..?

Nelixuk2003

To be honest I have never checked for codes after it stalled but the EML has never come on, I know that does not mean no codes are logged.

I'll check the coolant temp when cold, but I seem to remember it wasn't anything out of the ordinary last time I was looking at live Data.

As for "does it run better when hot", I have not let the car get up to temp since I changed the MAF Sensor.

Someone mentioned to me that it might be the MAP sensor??? I know it measures absolute pressure but not sure if it would cause this.

I just find it strange that it runs and revs great for 40 secs then gets these issues.... !!!

I cannot look today but will check the above out tomorrow and report back.

Thanks

mullingar

Nelixuk2003 wrote: »

To be honest I have never checked for codes.......

..... I just find it strange that it runs and revs great for 40 secs then gets these issues.... !!!

Two things here, scan all codes first.

The second is odd. Try and recalibrate the egr valve just in case too much exhaust is being recycled

Nelixuk2003

mullingar wrote: »

Two things here, scan all codes first.

The second is odd. Try and recalibrate the egr valve just in case too much exhaust is being recycled

Had a change of plans today, due to a poorly little one so the trip to the Zoo is cancelled. On the plus side, I get to play with the car!!

OK, told the car it's had a new EGR fitted as I was unable to find and re-calibrate/configuration method available in PP.

Also fitted new MAP Sensor..... Just in case.

Can't start it as the battery is flat now

It's on charge and will report back later today.

Nelixuk2003

Ready for the next update???

Right this morning I fitted a new MAP sensor and told the ECU that a newEGR was fitted. After charging the battery I have just been out and started the car, it still runs the same, wouldn't rev over 1500rpm and still got black smoke.

No codes stored when it stalls. I tried running it for a while whilst holding the revs at approx1300rpm to warm it up and the rev still fluctuated down to 1000rpm and back to 1300rpm constantly, after a minute or so it idle, still fluctuating, but didn't stall.

If i unplugged the MAP sensor it idled fine, plugged it back in and fluctuates. Next I unplugged the MAF and idle fine, plugged back in and fluctuates. tried unplugging the electrical plug of injector 4 to see if anything changed and same slightly rougher but not by much, pretty much as expected really, did the same to each injector in turn and the result was the same each time.

Just out of curiosity I unplugged the Electric Plug from the EGR valve and it idled fine, when plugged back in it continued to idle fine, still wouldn't rev over 1500 though. Also, after stopping and restarting the engine the fluctuating revs are back

Once the engine was up to temp it still runs the same.

I got an ABS/ESP fault flash up whilst doing the above, I have had this before and it went away by itself, I believe last time I had it I had just washed the car and we have had a a fair amount of rain so am putting that down to water ingress somewhere which I will tackle when/if I get the engine sorted. whilst the engine was running I thought I would pump the pedal to see if it would resolve the ABS fault and noticed that when the pedal was hard the engine idled better, if I kept it pressed and allowed the pedal to slowly lower, once it got to the bottom the engine fluctuated again. Looks like it could all be vacuum related.

I decided to unplug the vacuum to the can on the turbo and once the VVT arm returned to the top, the engine idled nice and smooth, plugged it back in and after a few seconds the VVT arm dropped and the fluctuating started again. I unplugged it once more and tried revving the engine again and it revs EXACTLY as I would expect a diesel engine to rev, basically a lot faster and a lot higher......... Still got the black smoke though

So what do you think folks??

mullingar

Very odd alright.

Im thinking multiple faults rather than the one that is causing the problem.

Re the EGR, Are you sure that there is no option to calibrate the EGR valve? So it knows what 100% open and 100% closed is? One way to eliminate this as the problem is to put in a EGR blanking plate.

Re Vacuum, the vacuum is only for the turbo (and maybe brake/clutch).

I think the thinking cap needs to go on, and ask why is there black smoke in the first place, even on idle. Black smoke AFAIK is usually caused by too much fuel or not enough air........ Any chance it could be burning lots of oil??

If its not burning oil, next I'd disconnect the turbo from the exhaust manifold to eliminate any turbo/DPF/exhaust problems and see if it revs freely. (Maybe the turbo is not spinning as free as it should?) Maybe take the EGR off the engine if you cant block it.

Nelixuk2003

I have searched PP and I cannot find any option to calibrate the EGR, I can calibrate other things on the car just not the EGR by the looks of things. I am going to fit a blanking plate and see how that goes.

I only thought the vacuum as, as you mention, the brakes use the vacuum from the servo and when I was pumping the pedal the engine idle changed, maybe that I am jumping to conclusions. Disconnecting the Vacuum from the turbo make it run EXACTLY as I would expect, revs nice and freely and nice and high 3000-3500rpm.

I agree that black smoke is unburnt diesel caused by either over fueling or not enough air, the reduced Air Flow in the graphs point to an air supply issue. There is some smoke at idle but it is very little, really only get LOTS of black smoke when revved.

there is oil in the turbo pipes but not enough to cause me any concern really, I have also flushed them out when I had the air system off the car, I suppose I could take all the pipes and intercooler off again and flush with petrol to be doubly sure. Burnt oil is normally blue smoke.

I have in the past removed the CAT/DPF from the turbo manifold and it still wouldn't rev but I could hear the turbo whistle.

the Turbo Cartridge has been replaced so I would have thought it should be spinning as it should.

One thing I will mention, when I take the air pipe off the intake side of the turbo there is a little more oil than I would expect. I put that down to the seal (Rubber O-Ring) on the pipe where it plugs into the rocker cover as there is a valve/diaphragm in there to stop it picking up oil that operates when the air is sucked through the pipe by the turbo, I thought that if it wasn't sealing the diaphragm would not close and it may be picking oil up. I have changed the seal (Rubber O-Ring) but not really had the new seal on long enough to tell if there is any improvement.

Row

If you could get your hands on 4 good s/h injectors and see if they solve the problem...that way you can rule out injectors.
May also be worth carrying a compression test to see if any of the cylinders are down....There could be mechanical damage inside the head so this would rule this out.
BTW disconnecting the egr valve flags the abs fault...:-)

Nelixuk2003

Row wrote: »

BTW disconnecting the egr valve flags the abs fault...:-)

Ahh! That makes sense...... Not

mullingar

Row mentioned injectors, I'd be interested to know do you still have the same amount of smoke when you disconnect one electrical connector at a time???

Did you do a leak-off test???

Also, a +1 for a compression test.

Also #2, I was given a dead DV6 engine as a donor and after stripping it down I discovered the reason why it was running like a pile of poo, most of the x16 inlet ports inside the head were completely carbonised up and air wasn't getting through :eek:

Row

Nelixuk2003 wrote: »

Ahh! That makes sense...... Not

Tis hard to believe but most peugeots /Citroens with these engines flag a communication fault between engine and abs ecu when the egr is disconnected which in turn flags the abs warning....Check the abs ecu and there should be a C1208 fault logged.....;)

umop apisdn

Have you cured the black smoke - injectors problem, or at least had them properly tested and ruled out ? Because until you do you're wasting your time with the rest of the emissions system.

Nelixuk2003

mullingar wrote: »

Row mentioned injectors, I'd be interested to know do you still have the same amount of smoke when you disconnect one electrical connector at a time???

Did you do a leak-off test???

Also, a +1 for a compression test.

Also #2, I was given a dead DV6 engine as a donor and after stripping it down I discovered the reason why it was running like a pile of poo, most of the x16 inlet ports inside the head were completely carbonised up and air wasn't getting through :eek:

I did not rev and check for smoke when I was unplugging the injectors

I did a leak off test when this first happened, results as follows:

Inj 1. 50ml
Inj 2. 80ml
Inj 3. 60ml
Inj 4. 70ml

I was going to take them all out and get them checked anyway but was only able to get Inj 1 & 4 out, number 4 was replaced as the company testing them said it was goosed and number 1 was fine, I have programmed the replacement injector too.

I will see if I can loan a compression tester and try that.

As for the inlet Valves being choked........ That had crossed my mind , I don't fancy having to take the head off :eek:

Row wrote: »

Tis hard to believe but most Peugeot /Citroens with these engines flag a communication fault between engine and abs ecu when the EGR is disconnected which in turn flags the abs warning....Check the abs ecu and there should be a C1208 fault logged.....;)

I have cleared the fault now but I will bear it in mind when I disconnect it again to aid in the fitting of the blanking plate

Nelixuk2003

umop apisdn wrote: »

Have you cured the black smoke - injectors problem, or at least had them properly tested and ruled out ? Because until you do you're wasting your time with the rest of the emissions system.

I Think I need to invest in a puller to get them ALL out and tested properly.... again.

Row

The injectors should come out easier when the engine is good and hot.

Nelixuk2003

I'll get her nice and hot before I start removing them.

It was a bugger to start again after having the last 2 out, ended up using a few squirts of Lighter Gas

Nelixuk2003

Well, I have a Thunder Storm here now no won't be doing anything else tonight, hopefully it will help clear the air and I will have good weather tomorrow.

Nelixuk2003

mullingar wrote: »

most of the x16 inlet ports inside the head were completely carbonised up and air wasn't getting through :eek:

I don't suppose there is anything I can throw down the inlet ports to get rid of it all is there or is it a strip down?

Dia1988

Nelixuk2003 wrote: »

I don't suppose there is anything I can throw down the inlet ports to get rid of it all is there or is it a strip down?

There are special tools available

I just used an adapted hoover nozzle to scrape the carbon then it was immediately vacuumed up

mullingar

You dont have to take the complete head off to inspect the x16 air inlet channels. Just remove the big top black plastic air manifold piece.

To get this off you need to undo the EGR system (EGR/cooler/pipe) and glow-plug wires to gain access to the high-pressure fuel rail and undo each of the 4 pipes on this manifold (17mm AFAIK) and also remove the pipes/cable conduit for the injectors. Once these injector pipes/cables are removed take off all the nuts for the air manifold (dont miss the 2x bolts on each rear top corner). This will pull off but may need a bit of teasing. Once off you can see how carbonised the head's inlet channels really are.

If you go down this route, it would be a good idea to get the engine hot first to help remove the tar'd in injectors for inspection and it will be hot to also help with the glow-plugs removal to do a compression test. Take extreme care with the glow-plugs as they might be wedged firmly in and snap off, make sure you have a deep 8mm socket and good penetrating oil for this job.