robk007 Posted December 21, 2009 Share Posted December 21, 2009 Hi all, Thought it might be helpful to record my misfire problem and solution. The 2001 Discovery II TD5, 80k miles, with a fsh started 'misfiring' under load and above about 2,500 RPM. Of course being a diesel misfire is not the correct term - but it ran rough and would not pull, seemed short on power. The problem was only apparent under load, when accelerating hard, or uphill and only when revs got beyond 2,500 or so, although this varied a little between 2,500 and about 2,900. The injector harness has been changed for a new one with improved sealing. No problems starting, idling or driving gently about town or up to about 65mph so long as acceleration is gentle. A dealer check showed no fault codes, although the air flow was a little low so they swapped out a MAF meter, no improvement, so they put the old one back in free ( amazing) After lots of searching on the internet I cam up with a long list and started at with the simplest and cheapest items. Step 1) Checked red plug on ECU, still some oil despite injector harness change, must be residual oil in engine harness, cleaned it out, no improvement Step 2) Checked other end of harness where new injector harness plugs into engine harness, no oil step 3) Removed turbo heat shield and disconnected wastegate actuator rod, found wastegate to be very stiff. It freed up easily with some oil, replaced everything and problem solved - its great to have full power back. It seems as if the wastegate was not opening under heavy load, so boost pressure was geeting too high and so the ECU was shutting down fuelling to protect the engine, hence the rough running and poor performance. My lesson learned is that the misfire did not appear to be the same cylinder as it was more random than that, and it must have been a general lack of fuel for an instant. Hope this helps someone with a similar problem. Rob K Quote Link to comment Share on other sites More sharing options...
MartinK Posted December 22, 2009 Share Posted December 22, 2009 Great report - thanks for posting Quote Link to comment Share on other sites More sharing options...
disco111 Posted December 26, 2009 Share Posted December 26, 2009 Hallo robK007 Iam driving a Defender TD5 and have exactly the same problems,I had planned an electric surch for that problem today but your message changed my plans and I toke the actuator out of the car,the shaft of the wastegate was free to move but I tested the opening pressure and I noticed 1.1bar to START the movement of the rod at a length of 42.5mm (between the housing and the nut) I changed the length to 47.00mm and the opening pressure changed to 1.0 bar.I made a test run and the problem was gone!!!!! As you told the MAP sensor informed the ECU that the turbo pressure was to high and limited the quantity of fuel injected.(the so called misfires!!!!) Thank you very much it saved me a lot of work. Many many greetings from Gent Belgium Martin (Disco111) Quote Link to comment Share on other sites More sharing options...
Dave.Pretorius Posted December 31, 2009 Share Posted December 31, 2009 Hi all, Thought it might be helpful to record my misfire problem and solution. The 2001 Discovery II TD5, 80k miles, with a fsh started 'misfiring' under load and above about 2,500 RPM. Of course being a diesel misfire is not the correct term - but it ran rough and would not pull, seemed short on power. The problem was only apparent under load, when accelerating hard, or uphill and only when revs got beyond 2,500 or so, although this varied a little between 2,500 and about 2,900. The injector harness has been changed for a new one with improved sealing. No problems starting, idling or driving gently about town or up to about 65mph so long as acceleration is gentle. A dealer check showed no fault codes, although the air flow was a little low so they swapped out a MAF meter, no improvement, so they put the old one back in free ( amazing) After lots of searching on the internet I cam up with a long list and started at with the simplest and cheapest items. Step 1) Checked red plug on ECU, still some oil despite injector harness change, must be residual oil in engine harness, cleaned it out, no improvement Step 2) Checked other end of harness where new injector harness plugs into engine harness, no oil step 3) Removed turbo heat shield and disconnected wastegate actuator rod, found wastegate to be very stiff. It freed up easily with some oil, replaced everything and problem solved - its great to have full power back. It seems as if the wastegate was not opening under heavy load, so boost pressure was geeting too high and so the ECU was shutting down fuelling to protect the engine, hence the rough running and poor performance. My lesson learned is that the misfire did not appear to be the same cylinder as it was more random than that, and it must have been a general lack of fuel for an instant. Hope this helps someone with a similar problem. Rob K Rob Good info . Thanks . I have taken the liberty to reproduce your info on a South African website ,Landyonline My link What your experience reminds us is that the turbo is the secret to a lot of the performance issues with a turbo diesel. A turbo boost gauge has to be one of the easiest and most beneficial mods to a TD - and we should all have one ! Cheers Dave Quote Link to comment Share on other sites More sharing options...
EdwardStephenson Posted January 21, 2017 Share Posted January 21, 2017 Know this topic is from a while ago, but the information supplied has rectified my disco td5, thank you to the author for taking your time to write this Quote Link to comment Share on other sites More sharing options...
Deaf n Dear Posted March 24, 2023 Share Posted March 24, 2023 Thankyou so much for this post , been half way through my fuel system thinking fuel starvation then read this and 5 minutes freeing and adjusting waste gate it is fixed ! Brilliant ! Quote Link to comment Share on other sites More sharing options...
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