Intermittant rough running fault

[gt.jacko]

Hi I have a defender fitted with a 4.2 lse engine and auto box, the last couple of times i,ve driven it it has a really bad running fault, it will suddenly start to run really rich clouds of black smoke from exhaust and I can almost see the fuel gauge going down :'(. If you stop it and restart it seems ok again until revs get up above 2000 rpm , this morning i drove into stockport which is 15 miles away from me on the way there it never missed a beat then coming back it did it nearly all the way home on and off bloody thing anyone any ideas please.

Cheers
            gary :help:

[Rossko]

Dried leaves or sock in air filter box, faulty oxygen sensor, faulty coolant temp sensor (the EFi uses a different one from the gauge, don't let that confuse you), faulty Airflow Meter, chafed wires (check where your loom has been put through the bulkhead), split vacuum pipe to fuel pressure regulator or duff regulator, pinched fuel return hose.

[Bowie]

Coolant temp sender?

Loose air flow meter connection? These corrode slowly over time and make running 'interesting'.

Lambda probe.

Pretty much all it can be -if it all looks OK, then try the Hotwire diagnostics in the back of the Haynes manual -it's a lift straight from the LR workshop manual.

[gt.jacko]

thanks guys will have a look a those as i need to get it sorted it drinks fuel at an alarming rate when it goes off on one cost me £20 to do 32 miles yesterday and of course it wont idle at junctions etc so it,s apain in the backside to drive like that

[Range Rover Blues]

Quick question, did the installation include ALL the engine sensors, road speed, gearboc etc and what tune select resistor is fitted?

[gt.jacko]

It did n,t include the rd speed sensor but everything else is fitted it has been running fine this fault has come on recently, oh and I dont know what tune select is fitted without having a look as i cant remember.

[Range Rover Blues]

Road speed sensor doesn't make a massive differnence on it's own.

Does sound like either an air blockage or sensor fault.

[gt.jacko]

Looks like it might be air mass sensor as when fault appears if you disconnect air mass sensor it makes no difference to the running of the engine , any ideas best place to get one at the right price?

Cheers  :)

[Range Rover Blues]

Someone said new ones were £50 on E-Bay.

Just check but I think the 4.2 uses the same as the 3.9, 3am and 5am are interchangeable too.

[gt.jacko]

Just looked at my air mass sensor to get part no of it and it has no identifying no,s on it at all any ideas what part no could be most of the sensors advertised on ebay ask for part no of your old one typical

[Range Rover Blues]

http://cgi.ebay.co.uk/Land-Range-Rover-Discovery-V8-EFi-Airflow-Meter-3AM_W0QQitemZ390065552278QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item5ad1b7fb96&_trksid=p3286.c0.m14&_trkparms=65%3A12%7C66%3A2%7C39%3A1%7C72%3A1683%7C293%3A1%7C294%3A50

http://cgi.ebay.co.uk/NEW-air-flow-mass-meter-sensor-Land-Range-Rover-ERR5198_W0QQitemZ250441820195QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item3a4f7ee823&_trksid=p3286.c0.m14&_trkparms=65%3A12%7C66%3A2%7C39%3A1%7C72%3A1683%7C293%3A1%7C294%3A50

[Range Rover Blues]

Or ask Martin

http://cgi.ebay.co.uk/Range-Rover-Classic-94-LSE-4-2-EFI-V8-Air-Flow-Meter_W0QQitemZ180380712000QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item29ff873c40&_trksid=p3286.c0.m14&_trkparms=65%3A12%7C66%3A2%7C39%3A1%7C72%3A1683%7C293%3A1%7C294%3A50

[gt.jacko]

Looks like it was air mass sensor , borrowed one of a mate and tried it ,seems ok now going to give it a longer run tomorrow, oh one question which tune select resistor should be fitted to this, it has o2 sensors but no longer has cats fitted.

Cheers
            Gary

[Range Rover Blues]

Then you can run it with either of the UK market ones, I'd need to check but I think therer were 3 fitted most of the time.

One is for a cat equiped car, one obviously non-cat, thing is whilst the cat equiped might be slightly thirstier (had to run stoichiometric whereas non-cat can run lean) the cat equiped is definietly self-tuning whereas the earlier non-cat and non-lambda cars were not, so if there is a TSR for non-cat lambda cars, that's what you want, otherwise stick with the one for cat equiped, if that makes sense :-k