Is the Golf ALH engine not getting enough diesel?

Hello,

I drive a Golf 4 TDI with 90 horsepower, ALH engine (76,000 km).
The car has already had a new mass airflow sensor (MAF sensor) installed, which, according to the diagnosis from VW, was defective. However, the overall performance was still very low; I test-drove three other similar Golfs for comparison.
Now I've tested a tuning module, and with that, the engine really comes into its own.

Now, my question is: Which components are still responsible for the fuel injection amount, and how can I test them?
Unfortunately, the computer does not log any errors.
Of course, I'd rather not use a tuning box; at the moment, it seems to be compensating for a fault in a sensor.

Thorsten.

Hello Thorsten,

I find your approach to troubleshooting a bit strange!
Why don't you try the normal approach and first log the following:

1. Boost pressure.
2 LMM values.
3 Injection quantity

Thank you for the tips.
I can now rule out turbo boost; otherwise, the car wouldn't be performing so well with the tuning box installed.
Perhaps I should have the LMM (lambda sensor) checked again at VW, as it should still be under warranty.

Thorsten.

Hello,
Which sensors are still responsible for the fuel injection amount ?


The water temperature sensor in the EDC might be malfunctioning.
If the 'reported' temperature is too high (but still within a possible range), the engine will also not deliver its full power.
This is usually not indicated by the control system or stored in the error memory.
You can only detect the error if it is currently present and you are reading the measurement value at that moment.
I don't know if it's the same with your vehicle, or even if it's possible. But in our case, it was the same (although it was a truck - but the 'basic structure' of the EDC is probably similar).