Thread: The D2a Diesel with never changing fuel economy

Hello,
If you are running 32 inch tyres with normal gearing that will use a lot more fuel as the engine is working very hard to push you along, and why you use a lot less off road in low range and it much easier for the engine not working as hard.
Looks like you need the different gears for the crown and pinion. I want to fit bigger tyres but not untril I change the gearing and lose all the extra HP i have gained.
Ian

Originally Posted by justfishing

Hello,
If you are running 32 inch tyres with normal gearing that will use a lot more fuel as the engine is working very hard to push you along, and why you use a lot less off road in low range and it much easier for the engine not working as hard.
Looks like you need the different gears for the crown and pinion. I want to fit bigger tyres but not untril I change the gearing and lose all the extra HP i have gained.
Ian

there are plenty that have gone bigger tyres and still not affected the consumption in a td5, v8 i could expect.

Hello,
Yes can understand that, but 9% increase in diameter does effect performance hence losing power, more fuel, most people with a TD5 will notice a difference in take off at the lights with 32 inch tires, as quite a lot of people say so on this forum. Having spoken to a number of them even the V8's notice it as well.

Explain why when in low range better fuel consumption if it is not the gearing ??
Ian

Originally Posted by justfishing

If you are running 32 inch tyres with normal gearing that will use a lot more fuel as the engine is working very hard to push you along, and why you use a lot less off road in low range and it much easier for the engine not working as hard.
Looks like you need the different gears for the crown and pinion. I want to fit bigger tyres but not untril I change the gearing and lose all the extra HP i have gained.

Yes, but as per the title of this thread, my Disco is a magical one that DOES NOT change fuel economy! I get the exact same economy with 32" tyres as I do with standard size 29"! My tyre size does not effect it.

Just had a look at one of your fuelling files, mainly to see what you are getting at idle. My manifold pressures are slightly less than ambient at idle, which I was putting down to no boost and vacuum on the intake - but that is beside the point

One thing that jumped out was that your idle manifold pressure is about 6kpa above ambient. Is this normal with a VNT?
I also noticed that your manifold pressure is limiting at 205kpa. I know you have a boost box installed but I would have thought it would be set to limit at point closer to the 225kpa that the ECU limits to as standard? I don't run a boost box so I could be completely offtrack...

do me a favor, bypass the boost box and see what happens.

Originally Posted by Blknight.aus

do me a favor, bypass the boost box and see what happens.

To do that - all you need to do is un-earth it.. (remove black wire and insulate tape it)

Originally Posted by twr7cx

DISCOVERY II / TD5 / TD5 ENGINE / SETTINGS / OUTPUTS:

• TEST AC CLUTCH - working.
• TEST AC FAN - working.
• TEST MIL LAMP - working.
• TEST FUEL PUMP - working.
• TEST GLOW PLUGS - working.
• PULSE REV COUNTER - working.
• TURBO WATEGATE MOD. - ECU Communications Error - this is likely due to that it is disconnected and removed due to the VNT upgrade.
• TEMPERATURE GAUGE - working.
• EGR INLET MODULATOR - ECU Communications Error - this is likely due to that I have removed the EGR system.
• INJECTOR 1 - error - see below screen shots.
• INJECTOR 2 - working.
• INJECTOR 3 - working.
• INJECTOR 4 - working.
• INJECTOR 5 - error - see below screen shots.

The above screen shots are of the errors I received when testing Injectors 1 and 5. I tested them while the engine was running. The other three all tested as working.

You need to do the engine checks while the engine is off. The injector check manually fires the injector so you can verify it is working by listening for a click. You are getting communication errors because the injectors are controlled by the ECU when the motor is running.

Turbo waste gate: This test sends pulses from the TD5 ECU to the Turbocharger's waste gate modulator valve / solenoid. The valve should be heard clicking. This ECU controllable valve is not always fitted and communications may error if the test is done on ECU's not equipped with the valve.

EGR throttle inlet: This test sends pulses from the TD5 ECU to the EGR throttle inlet modulator. The modulator should be heard buzzing. This valve is not always fitted and communications may error if the test is done on ECU's not equipped with the valve.

Injector 1 to 5: This test sends pulses from the TD5 ECU to the respective injector. If fuel pressure is present in the fuel rail, the injector will fire causing fuel to be released at such high pressure that it can easily penetrate human skin with dire consequences. Therefore, great caution is advised if the Injector to be tested is not properly secured into its mounting.