Discussion
Hiya,
the RR has started returning worse MPg these last few weeks, and I'm wondering what would cause it. Its never been great- hell, who am I kidding? its like someones stealing petrol from me- but just recently Id say its 20-25% worse.
so..whats are your thoughts? needs a service? something else? is there something common to these that causes mpg to drop? it was serviced 5k ago if that helps, is the interval 6k?
Id appreciate your thoughts folks. ts a 2002 4.0 btw.
the RR has started returning worse MPg these last few weeks, and I'm wondering what would cause it. Its never been great- hell, who am I kidding? its like someones stealing petrol from me- but just recently Id say its 20-25% worse.
so..whats are your thoughts? needs a service? something else? is there something common to these that causes mpg to drop? it was serviced 5k ago if that helps, is the interval 6k?
Id appreciate your thoughts folks. ts a 2002 4.0 btw.
Any noticeable drop in performance? The fuel consumption on my 4.0 Disco 2 went south on a recent trip across Europe. Drpped to around 15mpg when previously it was doing around 19 on a run. It was also labouring when accelerating under load ie. up hills etc and it turned out to be the MAF sensor.
Was replaced last week whilst in for some tlc and it's running smooth again. Haven't checked mpg since but it makes sense that I won't be using as much if I am running smoother and more powerful for the same throttle position.
Rovacom fault read out should be your friend.
Was replaced last week whilst in for some tlc and it's running smooth again. Haven't checked mpg since but it makes sense that I won't be using as much if I am running smoother and more powerful for the same throttle position.
Rovacom fault read out should be your friend.
Denis O said:
Any noticeable drop in performance? The fuel consumption on my 4.0 Disco 2 went south on a recent trip across Europe. Drpped to around 15mpg when previously it was doing around 19 on a run. It was also labouring when accelerating under load ie. up hills etc and it turned out to be the MAF sensor.
Was replaced last week whilst in for some tlc and it's running smooth again. Haven't checked mpg since but it makes sense that I won't be using as much if I am running smoother and more powerful for the same throttle position.
Rovacom fault read out should be your friend.
interesting thought. its maybe a tiny amount down on 'performance' (such as it is!), its certainly not labouring, but its not perhaps as gutsy as it once was. again, only by a small amount though.Was replaced last week whilst in for some tlc and it's running smooth again. Haven't checked mpg since but it makes sense that I won't be using as much if I am running smoother and more powerful for the same throttle position.
Rovacom fault read out should be your friend.
any ideas on where i could get hold of a rovacom fault reader thingy?
Trip to local indy or possibly stealer dependent upon geography. MAF's can be cleaned. I read somewhere that Mr. Muscle oven cleaner does a good job but I guess at your own risk.
Mine was bad enough so that when I unplugged the MAF it made little difference, apart from more difficult to start, so I concluded the MAF wasn't doing a lot.
The "labouring" I mentioned was similar to how old cars would go when the advance/retard pipe on the distributor had come off or was leaking. It would be fine with gentle throttle but once you pushed hard on the throttle it wouldn't accelerate. It would get to 85 but with gentle throttle all the way up. With the new MAF it's back to normal.
Mine was bad enough so that when I unplugged the MAF it made little difference, apart from more difficult to start, so I concluded the MAF wasn't doing a lot.
The "labouring" I mentioned was similar to how old cars would go when the advance/retard pipe on the distributor had come off or was leaking. It would be fine with gentle throttle but once you pushed hard on the throttle it wouldn't accelerate. It would get to 85 but with gentle throttle all the way up. With the new MAF it's back to normal.
Denis O said:
Trip to local indy or possibly stealer dependent upon geography. MAF's can be cleaned. I read somewhere that Mr. Muscle oven cleaner does a good job but I guess at your own risk.
Mine was bad enough so that when I unplugged the MAF it made little difference, apart from more difficult to start, so I concluded the MAF wasn't doing a lot.
The "labouring" I mentioned was similar to how old cars would go when the advance/retard pipe on the distributor had come off or was leaking. It would be fine with gentle throttle but once you pushed hard on the throttle it wouldn't accelerate. It would get to 85 but with gentle throttle all the way up. With the new MAF it's back to normal.
My nearest Indys are theives, so Ill have alook myself. Is the MAF sensor attached to the airbox or near to it? They can usually be cleaned with electrical contact cleaner and a cotton wool bud, so I can probably attempt that without too much of a massive bill looming.Mine was bad enough so that when I unplugged the MAF it made little difference, apart from more difficult to start, so I concluded the MAF wasn't doing a lot.
The "labouring" I mentioned was similar to how old cars would go when the advance/retard pipe on the distributor had come off or was leaking. It would be fine with gentle throttle but once you pushed hard on the throttle it wouldn't accelerate. It would get to 85 but with gentle throttle all the way up. With the new MAF it's back to normal.
probably.
On mine it's about 6 inches behind the airbox on it's way to the plenum chamber. Not sure of the layout on a 4.0 P38. It's in a similar place to the Disco on a 4.6 P38.
It's pretty obvious being a plug fitting which is the only 1 in that area. From memory mine has standard Phillips screws. I remember my 996 had security torx fittings so I couldn't get it off. Had to be changed at the indy.
It's pretty obvious being a plug fitting which is the only 1 in that area. From memory mine has standard Phillips screws. I remember my 996 had security torx fittings so I couldn't get it off. Had to be changed at the indy.
Denis O said:
On mine it's about 6 inches behind the airbox on it's way to the plenum chamber. Not sure of the layout on a 4.0 P38. It's in a similar place to the Disco on a 4.6 P38.
It's pretty obvious being a plug fitting which is the only 1 in that area. From memory mine has standard Phillips screws. I remember my 996 had security torx fittings so I couldn't get it off. Had to be changed at the indy.
Thanks D, thats great. funny enough, the last time I did one was on a 996. Ill try that later when the missus gets back from wasting my money on 'essentails'.It's pretty obvious being a plug fitting which is the only 1 in that area. From memory mine has standard Phillips screws. I remember my 996 had security torx fittings so I couldn't get it off. Had to be changed at the indy.
Anyone else have any ideas what it might be, if its not the MAF?
then relax and don't worry about the "needing a new engine" scenario 
if not MAF then could be O2 (Lambda) sensor on one of the exhausts possibly...
ETA: I see that earlier posts suggest O2 sensor as well and that makes the most sense given the symptoms. Mine began to smell very petrol-y when starting from cold as it over fuelled the engine. New O2 as relatively cheap and simple to do and job done!
if not MAF then could be O2 (Lambda) sensor on one of the exhausts possibly...
ETA: I see that earlier posts suggest O2 sensor as well and that makes the most sense given the symptoms. Mine began to smell very petrol-y when starting from cold as it over fuelled the engine. New O2 as relatively cheap and simple to do and job done!
Edited by pontypool on Tuesday 22 January 18:14
pontypool said:
then relax and don't worry about the "needing a new engine" scenario
if not MAF then could be O2 (Lambda) sensor on one of the exhausts possibly...
ETA: I see that earlier posts suggest O2 sensor as well and that makes the most sense given the symptoms. Mine began to smell very petrol-y when starting from cold as it over fuelled the engine. New O2 as relatively cheap and simple to do and job done!
aces! can they be tested? Im pretty sure i read that theyre so sensitive that placing a meter across them to test them can cause them to fail?if not MAF then could be O2 (Lambda) sensor on one of the exhausts possibly...
ETA: I see that earlier posts suggest O2 sensor as well and that makes the most sense given the symptoms. Mine began to smell very petrol-y when starting from cold as it over fuelled the engine. New O2 as relatively cheap and simple to do and job done!
Edited by pontypool on Tuesday 22 January 18:14
how much for a new one/ pair and how much to fit? Just unbolt and unplug you reckon?
not a boat load of cash, I just found this http://www.britishparts.co.uk/.sc/ms/cat/Range%20Rover%20P38A--Fuel-Emissions but be careful as I htink there are different types depending on which year you are and also some of the sites simply sell the actual bit that goes into the exhaust and not the wiry bit with the connector.
Caveat Emptor...I am a P38 owner and not mechanic, although clearly there should be some sort of basic exam needed prior to purchase!
Caveat Emptor...I am a P38 owner and not mechanic, although clearly there should be some sort of basic exam needed prior to purchase!
Nervy :wave: other than JSF (I don't no if RPi have rovacom) the only other guy I know that I would use is out my way and he has a back door into the LR dealership. Unfortunately he's not that reliable when it comes to time keeping. Txt me if you want his number. He might do a deal for a spin in your Fiat......
One way for a quick check of the EFI system is to put a volt meter across one of the lambda sensors and see what is gives you at say 2000 rpm on light load. You should see the voltage cycling above and below 0.5V about once a second or faster. If it's slower, the sensor is becoming unresponsive and will need to be changed at some point. If the reading is pegged above or below 0.5v then either the sensor has failed or there's some other fault which is throwing the EFI out of wack. If only one bank looks bad then swapping the sensor over is a quick and cheap way to see whether it's the sensor causing it.
GreenV8S said:
One way for a quick check of the EFI system is to put a volt meter across one of the lambda sensors and see what is gives you at say 2000 rpm on light load. You should see the voltage cycling above and below 0.5V about once a second or faster. If it's slower, the sensor is becoming unresponsive and will need to be changed at some point. If the reading is pegged above or below 0.5v then either the sensor has failed or there's some other fault which is throwing the EFI out of wack. If only one bank looks bad then swapping the sensor over is a quick and cheap way to see whether it's the sensor causing it.
what do you make of the idea that putting a meter on the sensor can toast it?Gassing Station | Land Rover | Top of Page | What's New | My Stuff