1.4 TDI Fuel Consumption Under Full Load

Is it normal for my 1.4 TDI to consume more fuel in 5th gear at 3000 RPM with the pedal fully pressed than it does above that RPM? Can anyone tell me how much fuel it consumes at approximately 4000 RPM with full throttle?

hi,
How did you determine the current consumption?
greetings

Yes, that's the same with other TDI models as well.

I only read it on the multifunction display, and I've actually noticed for a while that when I, for example, give it full throttle in 5th gear at 2800 rpm, the fuel consumption suddenly spikes and then gently but steadily decreases until... I have to brake again anyway! But that's probably normal. However, I would have expected the fuel consumption to be highest at 4000 rpm. At 3000 rpm, I'm still getting close to 12 liters.

I only read that from the multifunction display, and I've actually only recently noticed that when, for example, I give it full throttle in 5th gear at 2800 rpm, the fuel consumption spikes and then gently but steadily decreases until... I have to slow down again anyway! But that's probably normal. I would have expected the fuel consumption to be highest at 4000 rpm. At 3000 rpm, I'm still getting close to 12 liters.

The current consumption refers to a value per 100 km.
That means that if you're traveling at 4000 RPM, you'll cover the 100 kilometers faster than if you're traveling at 3000 RPM.
Therefore, the consumption naturally decreases as the speed increases.
Assuming the consumption rate remains constant.
greetings

Hi,

As already mentioned, this is normal and has a very simple cause.

The MSG (which includes functions like traction control, driver preferences, and torque limitation) uses characteristic maps to limit the amount of fuel injected per cycle.

Within a single gear, the number of engine revolutions per distance traveled is constant and independent of speed (which makes sense), and therefore the number of strokes is also constant. In other words, within a single gear, the upper limit for the injection amount per distance unit (=instantaneous fuel consumption) is limited by these characteristic maps.

"As you move up the rev range," the injection is reduced, so at full throttle within a gear, the instantaneous fuel consumption decreases - which exactly matches the observations.

The maximum power usually occurs around 2000 rpm, which is also where the maximum torque is reached.

Your 12 liters at the AMF are quite similar to the maximum 13.5 liters at the ASV, which suggests that the AMF likely has a shorter gear ratio. This is because, despite having only 3/4 of the engine displacement, it can achieve almost the same fuel injection amount per distance traveled. Note that this is per distance traveled, not per engine revolution.

In the ASV (likely referring to a vehicle's data), the value also decreases as you go up, with a noticeable drop around 4400 - sometimes down to about 11 liters. This is only possible when going slightly downhill, as the speedometer needle is already approaching 210 km/h.

It is therefore a normal and explainable process.

Best regards,

Jan.

OK, thank you very much for the answers!