Disco II V8 slugish/low down miss

[cal415]

Hi All,
I recently purchased a 01/02 Disco II, Lovely car in great nick and only 49,000kms on it. Drive well but i have noticed a fairly large dead spot below 3k revs and Occasionally it will miss pretty bad down lower in the rev range around 2k almost like its about to stall completly, it might do this for 3-4 seconds then come to life. As it starts to rev you really feel it kick in after 3k and really starts to pull hard, not sure if this is normal for the big 4.0L but i have to say i am unimpressed with its low down torque at the moment and thought it there might be something i can do about this.

Any help would be appreciated.

Thanks,


Mick.

[loanrangie]

When was it last serviced, filters changed etc. Sounds like fuel starvation - replace the fuel filter and see if that improves things.

[4bee]

Sort of had this problem a few months ago.

1. Changed the plugs. 2. Gave her a bottle of Nulon Injector Cleaner. 3. Commenced using Vortex Premium Unleaded Fuel.

Hasn't looked back since. It now has power I never dreamt of & pulls up hills in top that always needed 3rd. This worked for me so who knows, it may for you too. style_emoticons/<#EMO_DIR#>/biggrin.gif

[101RRS]

Can be the fuel filter but can also be the following

Distributor cap/leads - breaking down
The connector to the airflow meter momentarilily breaking contact and shutting the engine down - the vibration then causes contact starting the engine up - just pull off the connector and and put back on with some WD40 in there

Both of these things have happened to my V8

As suggested get a tune up but make sure a genuine dist rotor is used - the aftermarket ones are not reliable and cause no end of grief - the saving is not worth it.

The other point is that the V8 doesn't have a lot of torque just off idle but picks up real quick - idle should be up around 800rpm - tune up will sort out.

Just a couple of suggestions

Garry

[PhilipA]

Fellas, an 01/02 disco 2 is a motronic "Thor" motor. I take it that it IS aV8 petrol.
It should have tons of torque below 2000.
It does NOT have a distributor
It does have a completely different TPS.
So, the first thing I would look at is the plug leads, and maybe replace them.

Then have a look at the coil packs. If you see gooey stuff around any of the coils you have zee problem.

The plugs are platinum and need replacing at 120,000 K???? They are platinum and cost about $20 each. Ouch. but you can ONLY use the specified plug as the motronic measures the resistance across each plug.

If this does not work you should take it to a specialist with a diagnostic set up as there is something wrong, maybe with the motronic., which should show up on a Rovacom light or similar. The Motronoic logs any fault noted and measures duration etc etc.
Regards Philip A

[DEFENDERZOOK]

<span style="color:blue">yeah...what he said....
if it was a blocked fuel filter it would be starving at high revs not at idle....
it sounds to me like it might be cross firing....


go out at night in pitch black and start the engine and pop the bonnet...
look to see if there are any sparks visible while you get someone to blip the throttle to make it missfire...
check around the coil and down to the plugs...
DO NOT TOUCH ANY OF THE LEADS WHILE THE ENGINE IS RUNNING
if you do this once you will definitely remeber for next time...

if you have any sparks visible you have a problem.....
make sure that the leads are on the plugs properly....
and that you have the right plugs....

this is a start and can be done now....it only takes a few minutes....
let us know how you go...</span>

[PhilipA]

I thought later that a common problem is the crankshaft angle sensor dying, and it starts as an intermittent miss. The diagnostic should identify this. There is also a sensor on the camshaft.
Regards Philip A

[cal415]

Ok, Thanks guys, will try some of the things suggested... Its actualy been serviced just before i picked it up and it also took a trip to the land rover dealer here in newcastle who fixed a number of things on it, It was running really rich to begin with and blowing some black smoke but they sorted that out, according to them it was a blown fuse but that sounds a little strange to me.

According to them its still covered by new car warranty for a few months yet so i am planning on getting it all sorted out before thats over. It seems to happen on the crack of the throttle but only below 3000rpm, also when backing off i noticed it drops low in the revs down to under 500rpm then bounces up to about 1200 revs then up and down before slowly settling in around 700-800rpm - Similar to the probs i had with my Commodores idle air control valve but this eventualy holds an idle.

Its also chewing through alot of fuel, not sure what the usual consumption is like for a 4.0L 5 speed but getting roughly 400k from 80 bucks worth of optimax at the moment, thats worse then my VT SS 5.7L when i am give it a bit of stick around town.

The crank angle sensor thing sounds bad... reminds me of my VL Commodore...


thanks again!

[PhilipA]

That is a symptom of richness, and yes the 4.0 has an IACV.
In that case it is probably the temperature sensor. This is a simple cheap part. It should be simple to diagnose too. You would think that this should have been cured by now , so maybe it is something obscure.
I am not sure the Manual Disco 11 has the Thor engine, but I think it still has motronic.

Look up Google for "Thor Rover V8" to see what the Thor inlet manifold looks like and whether yours is one and let us know.
Regards Philip A

[cal415]

Yes, looks like a thor....

[Bytemrk]

Cal415 Wrote:
<div class='quotetop'>QUOTE</div><div class='quotemain'>Its also chewing through alot of fuel, not sure what the usual consumption is like for a 4.0L 5 speed but getting roughly 400k from 80 bucks worth of optimax at the moment, thats worse then my VT SS 5.7L when i am give it a bit of stick around town.
[/b][/quote]

style_emoticons/<#EMO_DIR#>/biggrin.gif style_emoticons/<#EMO_DIR#>/biggrin.gif style_emoticons/<#EMO_DIR#>/biggrin.gif Get used to it style_emoticons/<#EMO_DIR#>/biggrin.gif style_emoticons/<#EMO_DIR#>/biggrin.gif style_emoticons/<#EMO_DIR#>/biggrin.gif


That's about normal......... your VT isn't a 2 tonne truck.. is it? style_emoticons/<#EMO_DIR#>/biggrin.gif style_emoticons/<#EMO_DIR#>/biggrin.gif

I have the same motor - only auto - round town those numbers look right... you should find it loves the open road and your econony really improves - particularly using cruise.

I get around 20l/100km around town ..... but out on the open road ( even pulling 1 tonne of trailer) I can get that down to 16l/100km