TD5 Miss fire help please

[Shabba277]

I have a TD5 disco 2 that has a miss fire between 2000 to 3000 revs, I read the earlier posts and researched the problems, and sure enough there is oil at the ecu, so i have cleaned out the plugs stripped the ecu to bits, no oil  inside there, so i cleaned the ecu plugs with brake cleaner etc etc.. I have also replaced the injector loom, all connections are clean and connected properly to the injectors, but it still miss fires at the above revs, does anyone have any idea where else to look?
Thanks
Ady

[Porny]

Misfire.... do you mean at between 2000 and 3000 the car jerks as if being starved of fuel??

My next port of call would be to see the if the turbo waste gate is seized.   Due to the Rev range it occurs, it sounds as if you are suffering from overboost... and the most common cause of this is a seized waste gate.

Put a set of mole grips or similar onto the actuator arm, and see if you can make the turbo wastegate open by extending the arm back towards the bulkhead.  If you can't move it, then the wastegate is seized.

To free it off, it's easier if you remove the heat cover over the turbo, and the actuator arm (by removing the small 'c' clip)... then give wategate arm a drowining in WD40 (or similar when the engine is cold) and try and make it move - it should pivot back towards the bulkhead.

The other thing that can cause problems on a Disco Td5 is the boost modulator, but really you need to have it plugged into some diagnostic kit to see what it's doing.
(I'm only 50 miles from you next Sunday if you fancied a drive to Hibaldstow/Brigg)


Ian

[Shabba277]

Thanks for your response Ian,  It does jerk as if it being starved of fuel I suppose yes, but I had dismissed a fuel problem perhaps wrongly thinking that if it was a fuel or fuel supply problem it would occur all the time not just at top end revs?
   I had read in one of your earlier threads about the waste gate, I have tried to move this, and whilst it is very stiff to move it does move,  allbeit not very much should it be stiff or move alot easier?
  With regards to the boost mod, I had a garage do a diagnostic check, and they struggled with the results as the oil in the loom was flagging faults up everywhere, its had a lot of brake cleaner down the loom since then so it might be worth another check now?
Thanks Again
Ady
 

[Porny]

With the actuator arm unclipped, the wastegate arm should move very easily (i.e. with no resistance)... if it's stiff, it will make the turbo slow to react to boost pressure increases - and will cause over boost.

If overboost occurs, the ECU cuts the fuelling until the manifold pressure is back below the the boost limit point.

It would be worth getting your Disco plugged in again, and ideally taken out for a road test with the live data being displayed - so that you can see what the maximum inlet manifold pressure is. If you start seeing figures in the high 130's (or 230kpa absolute you willl be getting close to  or over the boost limit point.
You would also be able to see what your boost modulator is doing....


Ian

[Shabba277]

Thanks Ian, I will check that arm again if the sun comes out tomorrow, in the mean time today though I stripped out the injector loom again, went right through everything, cleaning out & drying properly, also noticed that the wires above the aircon pump were chaffed through, someone mentioned on a previous thread this causes my symptoms, also the plug just along from the egr valve was not pushed home right, these items my be coincedental but the truck, touch wood went fine today, no hicups at all,  I will see how it goes tomorrow as it may have been just a dream? 
  You mentioned getting over this way this weekend, is there something on at kirton Ian?
Thanks
Ady