SLROC Forum

I have a 1999 Discovery TD5 which has an annoying mis-fire normally about 3000rpm . Have had it to  main dealer,local Indy 4x4 and have had specialist out to it with all necessary diagnostic gear. Have now spent about ?1500 in search of cure but no luck. Can anyone please suggest where to try next,willing to travel for answer to this.
Help !!!!

how is it above and below 3000rpm?

As a cheap diagnostic, disconnect the electrical plug from the Mass Air Flow sensor on the air intake and take it for a run to see if your symptoms dissappear. If they don't then it is something else but if they do, bingo! Buy another one and job done. They get contaminated quite easily and should be changed every 40,000 miles. No problems with doing this for a test but it will probably harm the fuel consumption and emissions so don't use it as a fix.

Hope this helps, Calum.

I'm going through the exact same thing, get it on nanocom to help you track it down.  have you tried fuel filter,induction hoses, sticking wastegate, oil in the injection harness, the waste gate modulator or the harness connecting it (it rubs through), maf, fuel pump, injector seal's there's a lot to choose from buddy i tried working my way through it without using the computer, but i would never have suspected a short between the ecu and the wastegate mod, just before you get too excited remember your td5 limits your revs until its warm!!!!!  good luck m8 let us know how you go, Tio

Thanks guys for the quick response,brilliant forum
Above and below still slight but worse at 3000.
Have replaced air flow meter with L/R part, no better
Have replaced as above,air flow meter,injector wiring loom,engine bay wiring harness,various sensors etc as advised by main dealer.
Have had it on various diagnostic machines including main dealer fuel pump checks out ok . Really need someone who knows TD5's to look at it for me . Not saying others dont know but just feel needs that specialist who ha been there done that !!!
Again many thanks and if anyone can suggest someone please do,otherwise lov my TD5.
Thanks again to all

Hi tio
Have yu sourced your problem and cured it ??
Thanks for your suggestions

Have you checked the ECU is not full of oil? remove from car and stand it up on end with the sockets down the way. Leave to stand for a bit and see if oil starts dribbling out.
See the website link in my profile, he is a mate of mine and has been working on quite a few Td5's up this way lately, some with similar issues!

Not yet lol the next area is as rangerovering mentioned about cleaning out the ecu( dunno if the oil has penetrated the ecu housing), the significant find from nanocom is that the boost mod is  not recieving info (remains at 0 when driving around under load) and overboosting the ecu is then holding ti back,, so is the oil in the loom blocking the signal or is the harnes faulty it's unlikely to be the boost controler is faulty as it was a gen lr replacement.

...................See the website link in my profile, ..................

There is a wee software issue at the moment which stops viewing profiles so suggest you either PM the link or post it on the forum

T

When I bought my Defender TD5, it was very reluctant to go above 50mph. Not so much a misfire as a jolt and a total lack of oomph. Made overtaking lorries a riot!

I know for a fact that the friend I bought it from never took the car above 50mph (rarely above 40) in the eight years he had it.

A bit of Googling suggested something turbo-related had got stuck because the car had never been used in anger. (I'm not very technically-savvy and can't remember what it was).

The solution was to locate said bit and apply liberal amounts of WD40, or to continue driving like a nutter until it freed itself off. I opted for the latter, and it seemed to do the trick!

Hope this helps.

What you describe Udo sounds lot like a sticking wastegate, which is very common on the td5 at a certain age. It usually comes with an overboost error in the ECU and turbo pressures at the MAP above 1.3bar (230kpa or so). It's easy to fix with WD40 or similar.

Maybe jwsspca could record fuelling data when driving with a nanocom so we can have a look. It might tell us something (failing MAF, MAP, sticky wastegate, etc should be visible then).

Hi Folks
Again many thanks all ideas greatly appreciated,will try to track down someone with nanocom or similar and get back to you