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Thread: Sudden Power Loss - Lumpy Idle

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  1. Re: Sudden Power Loss - Lumpy Idle 
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    Quote Originally Posted by Amphitryon View Post
    That explains something. I had noticed that the car has two exhausts and each looks to have a cat in-line as you might expect if they were independent, but there is only one turbo. Any idea why they didn't split after the cat to save fitting two.



    So why would the diesel fail to ignite? I can only think of three reasons:
    1. Too little compression.
    2. Too cold - glow plug not working?
    3. No air, possibly because neither intake valve is opening.


    Are there others?

    As the original loss of power hapenned at speed, no 2. seems unlikely. No. 3 would be consistent with Crasher's idea about ejected valve fingers. If both inlet valve fingers on the same cylinder were ejected wouldn't that leave the inlet valves not opening (always closed)? I am sure I have seen a video in wich the valve covers can be fitted (and therefore presumaby removed) wih the injectors still screwed into the head but with the pipes from the injector pump removed.
    Okay.... will try get cam cover off in the week when get space to move car
    Thanks.
     
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  2. Re: Sudden Power Loss - Lumpy Idle 
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    Quote Originally Posted by Hannu5 View Post
    Diesel fail to ignite:- taking out too cold condition, so it wouldn't need the glow plugs as it was running up to temp. Then the obvious one is if valve sealing has been compromised, compression lowered it will not fire that cylinder. This could be if it's bent or destroyed a valve.

    All of this needs you to confirm what the status of the cam and followers are like. You probably can't get anywhere without doing this.

    The cams are driven from belt wheels without key, they are long taper as far as I know on this. Which means that jamming a loose rocker as it's ejected can alter the cam timing! Obvious valve contact potential. It can also make the cam jump belt teeth, the fuel pump is timed off the left bank cam set, so it can alter that too. All serious, but been seen on these with some regularity. You can see what we are getting at.

    MAF, obviously measures airflow on the fly. Unplug it and during start sequence it's then recognised as failed. They ecu has very competent base map to use in this eventuality on most cars. It does most of the job like this as it has multiple report lines of revs, temp, throttle, road speed etc etc to assist it. Makes a very good job of running engine without MAF. MAF could be considered as just refinement in strategic terms to give final "icing on cake" resolution by adding or subtraction of gain factors to load site data programmed into ecu base map.

    Tickover is monitored by flywheel pulses in more or less real time. If a pulse say for cylinder three arrives early or late, it'll pull or push injection quantity and timing to speed or slow that cylinder on next crank revolution. That's why modern motors haven that flat steady idle characteristic. So it'll try it's best to compensate for lumpy idle.

    You've gotta get a look at those cams, think it's disconnect pipes, leave injectors, pull cover.

    Also the belts to see what's going on there. You'd hope it's alright, but it's central to what is happening here and you can't avoid it to appraise problem you have.
    Many thanks to everybody for the time and effort in some very detailed replies.
    I appreciate that the 1st thing to do (when I can get car next door) is look at the cams as other issues are probably not helping but not the main issue.

    Thanks all. Will update later in the week.
    Cheers
    Yangi19
     
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  3. Re: Sudden Power Loss - Lumpy Idle 
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    So. Finally managed to have a look! and Update on recent issues:

    Not managed to get car into next door garage as he too busy – but decided to go for it and have a look at N/S Cams/Rocker (fingers?) assembly today. Not much to lose! Car going nowhere at moment!

    1. Removed EGR Ally Rail from front of engine to allow access to cam cover bolts.Bit fiddly with 10mm nuts and Star Drive Bolts in awkward place… but managed that. (small advice – all way through removal …. If you can use a Magnet on a Stick when getting near end of thread to ensure you don’t lose any nuts/bolts… would be useful)ERG CAST ALLY PIPE REMOVED.



    1. Remove Injection Pipes.

    Have to remove ALL pipes from Pump/Injectors as it isn’t one side of the V and then another/ they cross over!(make a Note of which pipe goes where to the pump / and order removed (refit opposite I guess)


    1. Remove Water Expansion Tank for N/S Bank of cylinders. Shouldn’t be hard…. But those f****ng pipe clamps are a nightmare!!! (broke a T Piece in process). Cut the F****rs OFF and replace with Jubilee Clips!!!! J



    1. Move Elec cabling out of the way ( 1 cable clamp secured to nut on cam cover at back)




    1. Undo bolts for injectors for Leak pipes – start from back of engine. Be careful not to lose copper washer from back of bolt!….. do it slowly and make sure washer on the bolt as you remove (don’t just pull out)



    1. Pull all pipes / electrics out way, And Undo all 10mm nuts holding cam cover on ( one also at front near Cam Belt cover!).



    1. Manoeuvre cover off…. Small amount of prising in each corner/manipulation required.



    1. Cover off!!!!


    So once cam cover off….had a good look. The Cams don’t look bad for 180k car!!!

    Also noticed that the Cam/Valve configuration isn’t what I used to????? I would expect that One camshaft is operating Inlet and the other Exhaust? But looking at cam/lobe positions ……. That can’t be the case? Each Cam does Inlet AND exhaust on each Cylinder?? Is that Correct??

    Anyway: Found why that Bank was loud. All ‘Fingers’ still in place. But one of the hydraulic lifters had no resistance. Also (when used magnet into oil bucket) found lots of metal fragments next to that lifter L NOT GOOD.

    Will Update with few pics
     
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  4. Re: Sudden Power Loss - Lumpy Idle 
    #24
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    what is IMAGE SIZE FOR PICS?
     
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  5. Re: Sudden Power Loss - Lumpy Idle 
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    The valve layout is not quite what you expect on these.

    Rather than the four valves being arranged in conventional alignment and square to the cylinder head casting, they've rotated them about the cylinder axis. So looking down on them could be described as combustion chamber rotated 45degree anti-clockwise ish.

    This makes the finger followers look like they are going to different sides of the cylinder, as you've found. Seems like they've done it for dimensions as it puts the cam lobes closer together and shortens the overall length without skewing the rockers.

    Seems like intake could be inoperative as you've got fuel (white smoke warmed in exhaust) but no air, so no combustion on one cylinder.
     
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  6. Re: Sudden Power Loss - Lumpy Idle 
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    Intake Manifold Pressure is not MAF sensor. The G-71 Intake Manifold Pressure (MAP sensor) Located on the intercooler in the front of the car Under the front bumper.
    Take a suggestion. Do not disconnect sensors when the ignition switch is on. Will save you a lot of pain and unnecessary expenses
     
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  7. Re: Sudden Power Loss - Lumpy Idle 
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    Quote Originally Posted by Hannu5 View Post
    The valve layout is not quite what you expect on these.

    Rather than the four valves being arranged in conventional alignment and square to the cylinder head casting, they've rotated them about the cylinder axis. So looking down on them could be described as combustion chamber rotated 45degree anti-clockwise ish.

    This makes the finger followers look like they are going to different sides of the cylinder, as you've found. Seems like they've done it for dimensions as it puts the cam lobes closer together and shortens the overall length without skewing the rockers.

    Seems like intake could be inoperative as you've got fuel (white smoke warmed in exhaust) but no air, so no combustion on one cylinder.
    Thanks
    will try upload pics tonight.
     
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  8. Re: Sudden Power Loss - Lumpy Idle 
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    Quote Originally Posted by amiram View Post
    Intake Manifold Pressure is not MAF sensor. The G-71 Intake Manifold Pressure (MAP sensor) Located on the intercooler in the front of the car Under the front bumper.
    Take a suggestion. Do not disconnect sensors when the ignition switch is on. Will save you a lot of pain and unnecessary expenses
    OK.
    When I was under car last weekend I found a 'Plug' not plugged in...... Under Bumper / more to off-side. I Couldn't tell what I was plugging into - thought it was to do with secondary fan? But I guess that could cause the 'implausible' reading. That probably been unplugged for ... 6 months.... when the Steering Pump was replaced!!!

    Cheers
     
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  9. Re: Sudden Power Loss - Lumpy Idle 
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    A couple of pics for yesterday:

    20190302_134939 size.jpg20190302_141445 size.jpg
     
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  10. Re: Sudden Power Loss - Lumpy Idle 
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    Those cams look shot. IF you change them it is VITAL you also replace the oil check valves under the turbo, these are part of the reason for your floppy lifters.... When you rebuild, I strongly advise you to use a ZDDP oil additive so the news cams last long enough buntlines non EU6 diesels get banned totally.
     
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