4bd1

[County3.9]

Question for the ISUZU experts. Just came back from a trip and got 8km/ltr (12.4ltrs/100km). This was in a 4speed county, maintaining about 105kph on the highway,no roof rack,family of 5, not overloaded. My old man gets much better out of his county:mad:
Before I did this check I thought I noticed a drop in economy and now I've confirmed it! What should I check first??

[D110V8D]

The handbrake.:angel:

[Blknight.aus]

Air filter.
tyre pressure
all oils....

remeber theres differnet ratios in different boxes/tcases/diffs which will also account for the difference.....

if its none of those grab a digital "laser" thermometer (the point and shoot ones) and from stone cold monitor each individual exhaust port on the manifold and see if they all come up about the same. Its ok if they heat up faster from the front to the back so long as its not a massive difference say more than 10 deg C as this is due to the fact that the fan and the coolant are up the front and the rear cyl gets hotter first. once at normal operating temp they should all normalise to within 1 or 2 deg c.

[County3.9]

The handbrake.:angel:

Handbrakes not grabbing.

[County3.9]

Whats that looking for Dave?

[Blknight.aus]

air filter, loss of air in = rich running = bad fuel economy

tyre pressure, low pressure = higher rolling resitance= bad economy and short tyre life

oil, burt/sludgy oil= oil cooler not working corectly and core temp in engine high= high precompression temp=bad fuel economy

and the check on the exhaust is a quick way of making sure you dont have a lazy cylinder not pulling its weight or one pushing too hard, not achieveing anything and just burning fuel

[EchiDna]

i'll also take a stab and say monitoring the individual temps will tell you if the ignition is at the wrong point of the cycle...

anyway, Dave's your man for 4BD1 info, it's his job afterall :)

[Bigbjorn]

Thermostat. The 4BD1 is sensitive to operating temperature, and if the LR cooling system is up to scratch, will not reach the optimum temperature for both economy and performance. If you need one, don't go to an LR dealer, too bloody expensive. Go to an Isuzu truck or industrial engine dealer.