IAT/MAP Sensor Isolation: What Do You Think?

I found an interesting article on Fred's TDI forum.

http://forums.tdiclub.com/NonCGI/ultimatebb.php?ubb=get_topic;f=4;t=001193

It's about the temperature/pressure sensor located on the charge air pipe.
LLk is isolated because the motor's interference is causing inaccurate results.
delivers and thereby reduces engine power.

I'd like to hear your opinions on this... Do you think it's effective? Or has anyone experimented with it before?
They are sometimes talking about a 10% performance increase due to an accurate reading from the sensors (or, in any case, better than with the entire exhaust system).

CUALL

CHRIS

Hi,
That's an interesting thing. If I understand correctly, he insulated the temperature/pressure sensor and the cables (copper cables conduct heat from the engine to the sensor) behind the radiator.
You should extend the cable carrying the temperature signal into the interior of the vehicle and measure the voltage while driving.
Then, properly insulate the sensor and a portion of the cable, and repeat the measurement.
The result is likely to be interesting. The question is how much the amount of diesel injected depends on the temperature of the intake air.

I've observed the following effect in my TDI before:
After being stuck in traffic for about half an hour and then accelerating to full speed (after passing the construction site), the acceleration was quite poor. It only improved after a short period of driving.
I suspect that the entire engine compartment, including the coolant and the temperature/pressure sensors, got quite hot during the stop-and-go traffic, and then the heat had to dissipate afterwards.

Here's something else: I also read something about propane hoses on the page. Do they actually feed additional propane into the intake manifold?
It has to work. I know of a biogas plant that operates with combined heat and power (CHP). The biogas is fed into a diesel engine. This engine runs with a small amount of diesel (for ignition), and the main power comes from the biogas. It seems to be knock-resistant (due to the high compression of the diesel). However, it's possible that the engine's compression ratio has been reduced.

Okay, there's a lot to discover. Let's get started...

Regards,

Eike.

Read further on the page; you'll find other things there. What's mentioned about propane is correct. You just need to search for something like 'propane injection.' There are products like PowerShot 2000 or BullyDog propane injection systems available, which work with any TDI engine. However, you really need to be careful not to damage the valves.

I'm going to test this out over the next few days and then post the results here in the forum.

Have a nice day! But maybe don't start reading (on that page), you'll never finish, lol.

hehe

Hi.

I think that the author of the English post number 2 made some quite serious mistakes.

1. He describes an intercooler outlet air temperature at full load of approximately 200°F, which is 93°C.
Rainer's measurements, on the other hand, only showed approximately 50°C. This is not so far from the alleged optimum, which is 100-120°F or 38-49°C.

2. He isolates the air temperature sensor from the outside environment or cools it with ice to reduce the temperature of the sensor, which is artificially elevated due to heat leakage.

In reality, the actual sensor element (at least in the case of a "temperature sensor only" like the AFN) is suspended on thin support wires in the airstream. Therefore, it is practically impossible to increase the temperature of the sensor itself through external heat input.

Analog example: A soccer ball impaled on a roughly 50 cm long iron rod, and the whole thing held out of a car window at a speed of 100 km/h.
Now, you hold a welding torch flame to one end of the iron rod and hope that the creeping heat will warm the entire soccer ball, without being blown away by the wind beforehand.
Alternatively, it is expected that the football will cool down by 20°C when the flame is removed.

The reported temperature can actually be lowered by using a resistor in series with the temperature sensor.
For example, a 470 Ohm resistor reduces a measured value of 60°C to an apparent value of 40°C.

hi ulf,

I don't think it will make much difference at 100 km/h, but I suspect you'll notice a difference when you're in stop-and-go traffic and want to accelerate, because hardly any airflow gets into the engine compartment. Then, I think it could actually make a difference.

Of course, it's just theory, which is why I'm interested, and that's why I'm asking the experts here.

Sure, here is the translation of the text from German to English:

'cu' is a Spanish abbreviation for 'con usted,' which means 'with you.' It is often used in online communication to indicate that the sender is available to chat or talk.

Here is an example of how 'cu' might be used in a conversation:

Person A: 'Hey, I'm bored. Want to chat?'
Person B: 'Cu!'

This means that Person B is available to chat with Person A.

'Cu' can also be used to indicate that the sender is thinking about the recipient. For example, if Person A sends a message to Person B and then receives a reply that says 'cu,' it could mean that Person B is thinking about Person A and wants to connect with them.

Overall, 'cu' is a versatile abbreviation that can be used in a variety of ways. It is a common way to indicate availability, interest, or affection in online communication.

Hi.

Quote:

I don't think it will make a difference at 100 km/h, but I suspect you'll notice a difference when you're in stop-and-go traffic and want to accelerate, because hardly any airflow gets into the engine compartment then.

So, I think it could be the case. }

Hi.

You're right, but at a certain point, every comparison falls short.
As long as the engine is running, there is no stagnation in the intake manifold, whether the car is stationary or moving.
Regarding the comparison to soccer, the question would then be more like: is it now a wind speed of 50, 100, or 200 km/h?

Only when the engine is stationary can heat from the engine compartment "creep" from the rear into the sensor element.
But I suppose that at the latest, 5 seconds after the engine starts, the correct temperature will be reported again, meaning that the sensor element has registered the temperature of the flowing air.

You are absolutely right!

Hi everyone,

Okay, at least in the A3, it's pointless to thermally insulate the charge air temperature sensor. It's located right at the front of the plastic intake manifold, before it goes down to the intercooler, and it's quite far away from the engine.
As a test, I simulated lower intercooler temperature values for the engine control unit by adding a resistor, but I didn't notice any significant change in performance.

Best regards, Rainer.

Hello everyone,

I can only confirm Rainer's test with simulated temperature values. I replaced the intake air temperature sensor with a potentiometer inside the passenger compartment, thus simulating 0°C and, on another occasion, 150°C for the control unit during a test drive. Conclusion: No change in performance was detectable, even though the target boost pressure curve changed depending on the temperature!

Best regards,
Holger

Volkswagen Golf III TDII (AFN)

Hello Holger,

Can you confirm my assumption that the target boost pressure decreases as the intake air temperature increases?
What was the approximate change in boost pressure between the two extreme temperature values?

Best regards, Rainer.