Poor fuel economy

**hot rover** · 17th September 2006, 05:32 PM

I only seem to be getting 15L/100k from my 2002 td5 discovery auto. I have installed a new air filter this had no effect. Can anyone help

**Blknight.aus** · 17th September 2006, 05:38 PM

ease up on the right boot, and turn the air con off?

is the converter still locking up? is it picking overdrive?

has the exhaust colour changed?

**hot rover** · 17th September 2006, 05:47 PM

i have tried driving like an old granny and it made no differance. Normally i haven't got a lead foot. I drive with the gear stick in d for drive it seems to go into all the gears not real sure what you mean. the exhaust is black looks normal. I have only had the vehicle for 2 months and have had no better ecconomy than this. this is the around town. On the highway it comes better
it drops to 11.5L/100k, this is with cruise set at 105k/hr

**Blknight.aus** · 17th September 2006, 06:20 PM

other questions to ask...

how goods the fuel? (every now and then you'll get a bad batch that also has you running like a hairy goat)

what rubber are you running? (big wide tyres eat fuel same for aggressive tread patterns)

whats the tyre pressures like? (ditto for 15psi tyres)

hows the oil in the tranny? (if its old/burnt you will have tx hassles starting with shift lag all of which cost fuel)

what kind of roads are you driving on, lots of hills, sydney peak hour? (in my v8 disco my fuel consumption increased nearly 50 % over highway numbers for city cycle while in sydney)

how much weight is in the vehicle? (more weight will make it want to hang onto gears)

are you always driving into a head/cross wind? (in townsville I lived inland of work, in the mornings the winds were obliquely against me, then the wind would die off near lunch and be just about dead on headwind on the way home took me weeks to work out why I got better fuel economy on the night shifts)

not sure if any of that will help.... but at 11.5l/100km your within about 1l/100km compared to what I get on highway cycle but I drive the manual, aim for 95/100kph and try not to vary the boot position unless I need to downshift for hill climbs, or if the downhill speed is becoming dangerous.

**hot rover** · 17th September 2006, 06:39 PM

I only use bp desiel. There are different types of tyers on the vehicle on the back there are 2 goodyear a/tr and on the front there is 1 michelin and a eldorado, having said that i am going this week to have 4 bfg all terrains fitted so they all match up. I am not keen on having 4 different tyers on. The on thing i haven't checked is the tyer pressure, which could be some of the problem. The vehicle ie empty except for me i weigh about 100 kg. I drive in toowoomba normal town roads. The engine seems to take a long time to heat up I am not sure if this could cause the problem

**Blknight.aus** · 17th September 2006, 07:54 PM

hrmmm, slow to warm up....

how slow is slow.. big red takes about 10 minutes to get past the blue part of the gauge into the white bit then less than 5 from there to get to operating temp. I have the heater on full in the mornings as its still a little cold for my likeing down here in Albury Wodonga. On the way back in the afternoon it only takes about 5 mins to get up to temp.

As I understand it the fuel map is modded for cold running, sort of the digital equivilent of pulling the choke on an old petrol engine. So if all of your running is with the temp gauge buried in the blue I'm not surprised you have crappy fuel economy.

If its consitantly slow to warm up regardless of ambient temp Id be thinking your thermostat has failed open to check it with the engine stone cold remove the bleeder bolt on the head of the radiator and start it up. If the coolant flows quickly early then you have a dead thermostat.

Also be wary that while generally a nicely driven auto is more effecient than a manual an experienced driver can get better economy from a manual than an auto. I wouldnt mind betting that in general the blokes and blokettes who are posting economy stats to the forum know what they're doing gear selection wise.

if your lucky your economy hassles are just the thermostat Given all else is equal and Im carrying 300kg more on board than you on average theres no reason why your fuel economy is so much worse than mine.

Good luck with it

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