Coolant Temp. on "Faulty" EGR Valve

Hello,

I recently disconnected my EGR valve (I think it made a difference -> the car feels smoother somehow).

It is said that the combustion temperature increases at partial load, but I'm observing something different.

Today I drove 50 km on the highway at a speed of 120 km/h according to the speedometer, but the car doesn't seem to be warming up properly (Volkswagen Passat 35i 1Z, manufactured in 1994).
'Those who are familiar with the temperature gauge on the dashboard will know that it only shows two numbers: 70 and 110°C, with a line in the middle representing 90°C. In my car, the needle always stays between 70 and 80. However, according to the onboard computer (MFA), the engine oil temperature is normal, around 95°C.'

How has it been for you since the AGR broke down?
Is the coolant getting warmer?

Perhaps my temperature gauge is faulty (although I can't imagine that, as it behaves the same way on my old Golf TDI, where it only fluctuates around 80°C...).

Please share your opinions...

Hi David.

Hello,

I also had a problem with the cooling temperature on my Passat 1Z; it was only around 80°C. It turned out to be the thermostat. After replacing the thermostat, it now runs at a normal temperature (90-94.5°C).

Regards,
*Mario*

Hi.

I'm afraid I can't tell you anything about that, because in my case, there's this idiotic "computer-calibrated" stepper motor display that constantly shows 90° even though the actual temperature is between approximately 75 and 105 °C .

In theory, it might be possible to achieve slightly lower heat loss if the efficiency increases (only!) in the partial load range – some colleagues have reported slight reductions in energy consumption since their EGR valve broke.
Then the engine would take a little longer to warm up, but I think it should still reach the thermostat's opening temperature reasonably quickly in the summer.

Hello,
"I also had something similar with a Passat from 1994, gasoline engine. Since the oil temperature is normal, I suspect a faulty sensor on the coolant reservoir at the front of the cylinder head. That's what it was for me back then. I don't think there's any connection to the EGR system; it doesn't make that much difference."

Best regards, Albrecht.

Can you actually display the water temperature on the Climatronic system? I'm going to check that out on mine. I'm already curious about it!

Sure, here's the translation:

'I am writing to you today to express my sincere gratitude for your generous donation of $10,000 to our organization. Your contribution will help us to provide essential services to vulnerable populations in need.'

'We are deeply grateful for your support and commitment to our mission. Your generosity will make a real difference in the lives of those we serve.'

'Thank you again for your kindness and compassion. We look forward to continuing our partnership with you in the years to come.'

Hi,

That's possible with the Audi 100 (model year 1993) if it has Climatronic.
Is it channel 51?
Perhaps it's the same one for you too.

Hello,

It is evident that while the peak combustion temperature increases without an EGR system in the partial load range, the average temperature decreases.
Reason: Because no more "hot" exhaust gases are being drawn in, the cooler fresh air causes the engine to warm up more slowly.
I've also noticed that my A3 takes a little longer to warm up, especially when I pay attention to it. However, the differences aren't really dramatic; they probably depend a lot on the specific route and conditions (e.g., hilly roads).

Best regards, Rainer.

Hi Rainer,

Quote:

Reason: because no more "hot" exhaust gases are being drawn in; the cooler fresh air causes the engine to warm up more slowly.

And what about engines that have an exhaust gas cooler integrated into the EGR system (e.g., AXR)?
Would the peak value also increase there?

Hello Bertil,

I believe the peak combustion temperature depends on the available oxygen content (but I'm not sure).
Sure, here's the translation:

"Think about how you adjust the different flame temperatures on an oxy-acetylene welding torch – the higher the oxygen content, the hotter the flame."
Unfortunately, I can't tell you what effect cooler EGR gases have on the combustion process compared to uncooled ones.

Best regards, Rainer.

Passi_Fire wrote:

Is it possible to display the water temperature via the Climatronic system? I'd like to check that on my car.

I'm already interested in this!

Hi!

Channel 51 displays the water temperature, but unfortunately, it's only a calculated value. Try turning on just the ignition for 10 minutes without starting the engine, and you'll see that the engine reaches operating temperature even while stationary.

Best regards,
Uwe

Are you sure, Uwe? Have you already tried disconnecting the temperature sensor on the engine?

Best regards, Rainer.

Rainer K. wrote:

Are you sure, Uwe? Have you ever disconnected the temperature sensor on the engine?

No, I haven't tried that yet. But why does the temperature display on the climate control system go up and stubbornly stay at 90 degrees?

Best regards,
Uwe

Hi Uwe,

Oh, I see... that's just the "we don't want to worry the average driver" feature.
The same effect can be observed with the pointer on the instrument panel.
IMHO, it's similar with the display in the climate control system. However, since I have never disconnected the temperature sensor for testing or simulated different values using a resistor, I wouldn't fully endorse my statement .

Best regards, Rainer.

...ähem, ich meine, die Anzeige geht hoch, ohne dass der Motor läuft. PTry it out.

Best regards,
Uwe

Hi,

@Uwe:
Could it be that the coolant temperature display on the air conditioning system only becomes accurate after the engine has been started (i.e., when a changing signal is received)?
With my car's automatic climate control system, this indicator is already showing the correct information.
When the thermostat is defective: Display shows '74' to '80' (degrees Celsius).
After replacing the thermostat: The display shows '88' to '90,' which are the 'reassuring values for the average user.'

Hi!

The test car is an A3 from 1999. I used to own an Audi 200, type 44Q, from 1990, and it had the exact same issue, although that one had a completely different air conditioning system (with LEDs).
I'll give it a try and then post it.

Best regards,
Uwe