Question about consumption

Hello fellow DIY enthusiasts,

After three weeks, I finally have my AXR back. The repair didn't take three weeks, but my parents were very upset about it.
The LLK (coolant heat exchanger) was replaced, and the car is running well as before (@ULF 100PS - really not anymore ), but a phenomenon is making me somewhat suspicious:
The energy consumption meter shows a significantly lower consumption than it did before the repair - even my wife noticed it! Previously normal (5.7-6.1), now (5.1-5.5).
Unfortunately, the last time I filled up the tank, it was while pulling a caravan. Since the caravan wasn't my own, I can't comment on its handling characteristics. However, despite the increased weight of the caravan, the combination felt surprisingly nimble to me. The displayed mileage and the actual fuel consumption matched (275 km with a fuel consumption of 6.6 L/100 km, including 100 km with a trailer).

Was if the LLK was defective from the beginning? However, all target values were met.
Since the AXR is electronically "detuned" (240Nm), it's possible that I didn't notice the power loss caused by the slightly leaking coolant pump? The reduced energy consumption speaks for itself.

Hm...
We've recently added the 100 horsepower PD model as a station wagon to our company's fleet. Their fuel consumption is around 6.6 liters, or as I experienced on my last business trip the day before yesterday, 7.6 liters on the highway (with the maximum possible speed being used).

Compared directly to the one I have, I don't find it significantly faster; they are roughly on par. Only in the lower range does the PD model seem more powerful. In my opinion, the power delivery is too disharmonious.

But I think that, precisely because you're driving a VW, you should have noticed a decrease in performance sooner. However, theoretically, your theory could be confirmed based on the fuel consumption data. But are you sure that only the LLK (likely referring to a specific component) was replaced?

Hello Bertil!

How did you notice the slight leak in your LLK (liquid cooling system)? Did you detect any oil stains, or was it more of an auditory perception?

What about particle emissions? Were you able to clearly see the soot in the headlight beam at night, and have you noticed an improvement now with the new sealing compound, or was the leak so minimal that you couldn't detect any difference?

Regards,
Alex.

donalexo wrote:

Hello Bertil! How did you notice the slight leak in your LLK (liquid cooling system)? Did you detect any oil stains on it, or was it more of an auditory perception?

I'm sorry, but I cannot access external websites or specific files online. Therefore, I am unable to translate the text from the provided URL.

I think that's enough as an answer.

The thread also highlights the issue of the LLK (low-temperature coolant system) in the Golf 4.

I haven't experienced excessive smoke; the AXR is so verschandeln that you can't see any smoke trails in the rearview mirror at night. A noticeable puff of smoke (not a flame) can sometimes occur only when starting the engine at too low an RPM.

wrote:

Hm... We've recently added the 100 horsepower PD model as a station wagon to our company's fleet. Their consumption is around 6.6 liters, or as I experienced on my last business trip the day before yesterday, 7.6 liters on the highway (driving at maximum speed whenever possible).

Yes, that's normal. The PD motor isn't fuel-efficient when you have a heavy foot – I also achieve those values.

Quote:

Compared directly to the one I have, I don't find it significantly faster; they are roughly on par. Only in the lower range does the PD model seem more powerful. In my opinion, the power delivery is too disharmonious.

I can't shake the feeling that my car doesn't actually have 100 horsepower (the LPS measurement was 119.5 - unfortunately, it wasn't a calibrated testing facility, but the Ulf's DZR test confirmed it). I used to drive a 1Z for a long time, and compared to that, the AXR is like a sports car.
The AXR is particularly known for its balanced power delivery. Therefore, I can't understand your last sentence. Are you sure everything is alright with the car? "With my [vehicle/method], I can easily handle an A3 with 110 horsepower, even though the 'Pampersbomber' is considerably heavier than the A3."

Quote:

But I think that, precisely because you're driving a VW, you should have noticed a decrease in performance sooner. However, theoretically, your theory could be confirmed based on the fuel consumption data. But are you sure that only the LLK was replaced?

Yes, only the LLK (likely referring to a specific component) and a connecting cable were replaced.
Since the engine's performance was actually quite satisfactory (with significantly better handling than the 1Z, despite the higher weight!), I didn't notice it. In my opinion, the performance is the same as before (which is surprising!), but the fuel consumption has decreased.

I performed the airflow test in practice and got a reading of 2000-4000 cubic meters per minute.
PD Variant 8sec and my 1Z 8.29. Basically the same.

"By 'unharmonious,' I mean that the PD engine really hits hard in the low end, providing good torque. However, that power simply cuts off above 3000 RPM; you can feel a noticeable drop. The 1Z doesn't have that issue. It's a bit slower in the low end, but it pulls smoothly and consistently up to its 4000 RPM. However, the PD engine still manages to reach 190 km/h on a straight road, and even 200 km/h with a good run-up, according to the speedometer!" I've also noticed that I always drive my 1Z within a range of 2-2200 RPM, while the PD usually runs at a higher RPM because it seems to not perform well within that lower range.

The cars are new, both with around 15-20,000 km on the odometer. We have two of them, and they both perform the same. I don't have any problems keeping up with a 1Z TDI with a red "i" indicator. It doesn't accelerate away from me. Except for my weakness when it comes to driving.
But subjectively, the PD feels more powerful and sporty, but my impression is that it only feels that way, and it's not actually the case in practice.

Generally, I think the cars are okay, but when I drove one for the first time, my initial reaction was, "I'll only buy a diesel with an automatic transmission; you end up not using the gears at all with these things." They might just be really bad.

Regarding your LLK (likely referring to a cooling system component), it's possible that the hoses were swapped, which could have introduced "vacuum leaks" in that area previously.

x world one wrote:

I performed the pull test in practice, with results ranging from 2000-4000 RPM. PD Variant 8sec and my 1Z 8.29. Basically the same.

So, you have a Mega 1Z!!
I can also achieve the 8-second mark with the AXR, but my 1Z combination only reached around 9 seconds (which is acceptable considering its weight of 1250kg and 90 horsepower).

Quote:

When I say "unharmonious," I mean that the PD (presumably referring to a specific type of exercise or movement) really hits your lower back hard, meaning it puts a lot of strain on it. But above 3000 RPM, this force simply disappears; you can feel a noticeable drop-off.

Okay, so at 3000 RPM, mine doesn't stop - it happily revs up to 4000 RPM, and then it starts to feel a bit sluggish, just like my old 1Z engine, although it started feeling that way a bit later with that one.

Quote:

The 1Z doesn't have that. It just takes a bit longer to reach its maximum speed, but then it smoothly accelerates to 4000 RPM.

It's because the wastegate turbocharger can't generate as much pressure at low RPMs as the VTG turbocharger.

Quote:

The PD, however, can also reach 190 km/h on a straight road, and with a good run, it can even reach 200 km/h according to the speedometer! I've also noticed that I always drive my 1Z within a range of 2-2200 RPM, while the PD usually runs at a higher RPM because it seems to not perform well within that lower range.

I tend to drive my AXR at lower RPMs compared to my 1Z.

So, according to the navigation system (GPS measurement should be very accurate), my car is doing just over 190 km/h on the straight (193 km/h according to the GPS, but 205 km/h according to the speedometer!). That is well within the manufacturer's stated performance of 188 km/h.

Quote:

... Generally, I think the cars are okay, but when I drove one for the first time, my initial reaction was, "I'll only buy a diesel with an automatic transmission; you end up not using the gears at all with these things." They might just be really bad.

Yes, it's possible - if everyone is talking about it.

Quote:

Regarding your LLK, it's possible that the hoses were swapped, which could have caused "vacuum leaks" in that area previously.

Yes, a hose was replaced because the seal there was likely defective.


Here's something else about non-harmonious power factor:
Okay, here's the translation:

"Test drove the ARL (150 hp PD). I was almost thrown out of my seat – up to 2000 rpm, you'd think it's an old diesel with 54 hp, and then suddenly, from 4500 rpm onwards, you get a massive kick in the back that will make you feel refreshed." Good, the test car had ASR.

...
Here's something else about non-harmonious power factor:
Okay, here's the translation:

'Test drove the ARL (150 hp PD). I was almost thrown out of my seat – up to 2000 rpm, you'd think it's an old diesel with 54 hp, and then suddenly, from 4500 rpm onwards, you get a massive kick in the back that will make you feel refreshed.' Good, the test car had ASR.

not only is the 150 hp engine disharmonious! also the 130 hp engine! but, I cannot confirm that not much happens below 2000 rpm. the comrade also has decent power at the bottom. and from about 1600-1700 rpm, it really starts to pick up speed!!!

Bertil wrote:

Yes, a hose was replaced because the seal there was probably defective. Here's something else about non-harmonious power factor: Okay, here's the translation: "Test drove the ARL (150 hp PD). I was almost thrown out of my seat – up to 2000 rpm, you'd think it's an old diesel with 54 hp, and then suddenly, from 4500 rpm onwards, you get a massive kick in the back that will make you feel refreshed." Good, the test car had ASR.

I believe your car was drawing in unmetered air before, which caused it to consume more fuel. He probably got a whiff of the warm engine air.

Yes, a 150 horsepower PD engine would be something interesting. But he probably won't get the 330d that my boss has, thankfully, this car also has ASR .

Regarding our company's product documentation:
It's probably true that everyone was pushing it. Especially in the first few kilometers, no one was following the usual break-in rules. Since everyone else drives gasoline-powered cars, unfortunately, these cars are also driven like gasoline cars, meaning they are often revved up, even in the city.
Now that I own a diesel car myself, I drive it differently, and I only use the Autobahn (German highway) for high-speed driving to reach the maximum speed.
It wasn't easy for me to switch from my fairly fast car, a Golf2 16V with 130 horsepower and a weight of 950 kg, but with almost 3 liters less fuel consumption, it's worth it.

Hello,

Quote:

I believe your car was drawing in unmetered air before, which caused it to consume more fuel. He probably got a whiff of the warm engine air.

The engine cannot draw in unmetered air because there is always positive pressure behind the turbocharger!

@Bertil
It's quite logical that there's increased fuel consumption when there's a leak in the charge air system. The turbocharger essentially has to provide more air in order to reach the target boost pressure. It achieves this by increasing the variable turbine geometry (VTG) more than usual. This results in higher exhaust backpressure, reduced overall efficiency, and increased fuel consumption.
It's quite remarkable how long this can happen unnoticed, before performance degradation becomes apparent.
I once had a crack, about 2 cm long, in a hose, but the boost pressure didn't drop significantly, and there wasn't excessive soot production. From the background noise, it was possible to tell that something was leaking.

Best regards,
Albrecht.

Albrecht wrote:

@Bertil It's quite logical that there's increased fuel consumption when there's a leak in the charge air system. The turbocharger essentially has to provide more air in order to reach the target boost pressure. It achieves this by increasing the variable turbine geometry (VTG) more than usual. This results in higher exhaust backpressure, reduced overall efficiency, and increased fuel consumption.

I understand that already - that wasn't my direct question, but I'm surprised that I didn't notice the leak, neither in terms of performance loss nor in terms of soot production.

Quote:

It's quite remarkable how long this can happen unnoticed, before performance degradation becomes apparent. I once had a crack, about 2 cm long, in a hose, but the boost pressure didn't drop significantly, and there wasn't excessive soot production. From the background noise, it was possible to tell that something was leaking.

Did you experience a similar problem with the same symptoms?

From this, I conclude that various leaks in the turbocharging system are either not being detected or are only being found by chance (as is the case with me now).
I couldn't detect any significant changes in the background noise, except that the loader no longer makes such a noticeable "puffing" sound during operation when switching loads (when the gas is released).

I think a lot of turbocharger systems with leaks will be affected by the landing, and nobody will notice.

Bertil wrote:

So, you have a Mega 1Z!!

When I enter the values into the Excel sheet from Ulf, the result is very close to my 8.29 seconds. I used a diagram from the internet for the required torque curve and read off my values. I don't know where you are getting your values from. Have you all bought a VAG-COM device?

Sorry, this is off-topic, but I didn't want to start a new thread, and since we were already on the subject...
Please forgive me.

x world one wrote:

When I enter the values into the Excel sheet from Ulf, it comes out to be very close to my 8.29 seconds.

Just wait, then you'll have your big awakening!
My car was about 120 kg heavier than what was stated in the registration documents, while the AXR engine is only 20 kg heavier than what is indicated.

Is your 1Z also a station wagon? Otherwise, we can save ourselves the trouble of comparing the values.

According to the documentation, the weight is 1120 kg. However, it's a 3-door model. We can definitely do without that.

Hi Bertil,

Looking back at my time with the LLK leak and considering the fuel consumption values (which I record on my PDA), I can confirm the increased consumption. Now, with a similar driving profile, the consumption is about 0.3 to 0.5 liters lower.

At the time, my leak didn't affect the performance either... there were no differences in either the Ulf test (around 6.3) or the maximum speed (210 km/h according to the speedometer, 200 km/h according to GPS).

Best regards,

Jan, whose TDI is now approaching 30,000 miles.

Hello Bertil,

Quote:

From this, I conclude that various leaks in the turbocharging system are not always detected or found, or are only found by chance (as is the case with me now). I think there will be a lot of turbocharger systems with leaks that will be damaged by the landing, and no one will notice.

I think with smaller leaks, yes.

The check with the leaking oil wasn't very helpful for me back then, because the crack was exactly at the bottom of the lower hose of the radiator (where you can see everything so well through the bumper, longitudinal member, and underbody pan ).
Anyway, there were no oil stains on the road or any drips on the hose.
However, the whistling sound when the boost pressure was built up was quite loud. Even with a slightly open window, it was possible to hear sounds from the highway.
That will certainly vary depending on the leak.

Best regards,
Albrecht.

Hello Albrecht, hello Bertil!

Yesterday, I checked my power steering fluid and all the hydraulic hoses while the car was raised on jack stands.
The hoses and hose connections all appeared to be in good condition and leak-free.
I'm a little concerned about one thing. The lower pressure hose at the outlet of the intercooler is very slightly oily in the area of the spring clamp. Also, the underside of the intercooler is a little bit damp with oil. However, there are no oil droplets on it, it's just a slight trace.
I have now carefully cleaned the areas, and I will soon take another close look to see if my LLK (likely referring to a specific system or component) might also be experiencing any losses. That would also, in my opinion, be a good explanation for why my turbocharger builds boost very slowly.

Regards,
Alex.