Significant spark timing retard despite using 100 octane fuel in the 2.0 TSI engine

Hello,

My Polo WRC (engine CDLJ) is generally running smoothly, and when I give it full throttle, it performs as expected: strong acceleration and high fuel consumption (current value at approximately 200 km/h in 6th gear: about 30 liters per 100 km).
However, the logs constantly show significant WOT (Wide Open Throttle) ignition timing retardations of up to 5° KW, even though I always diligently use at least 98Oktan gasoline, and just yesterday I even put in half a tank of Aral Ultimate with 102 octane.

The other log data, such as boost pressure control, turbocharger vane adjustment, fuel pressure control, and lambda sensor voltage, do not show any anomalies; the deviations from the set points are minimal.
The Pmax air mass is 175g/sec.
According to MWB32, the lambda learning rates are, if I recall correctly, within a range of +/-5%.

I haven't thoroughly tested Vmax yet.
Yesterday, on a flat stretch of road, I briefly revved it to 5600 rpm in 6th gear, according to the tachometer, which translates to approximately 234 km/h (the manufacturer's stated top speed is 243 km/h). Whether he would have been able to reach the missing 200 rpm seems doubtful to me, because a significant amount of time had already passed between 5400 and 5600 rpm.
In 5th gear, theoretically, he would be exceeding the maximum power output (Pmax) at maximum speed (Vmax), so 6th gear is... Mode of operation for the maximum speed gear.

Regardless, I put far less weight on top speed tests than on performance calculations based on acceleration logs – *provided* that the vehicle weight, the relationship between maximum power and top speed, the overall gear ratio (RPM to km/h), and the specific conditions of the log (slope/grade and wind) are known with certainty.

The power curve for my engine, as calculated in the third chapter. While the torque typically exceeds the nominal value of 350 Nm by about 20 Nm, the peak power usually reaches an average of around 216 hp (nominal value: 220 hp).
Current mileage: 1500 km.

If it's true that 2-liter TSI engines typically have a wider range of variation, with values tending to be higher rather than lower, then the figures mentioned above are consistent with that. The ignition timing retard and the resulting relative power loss are, in my opinion, logically connected.
So, the question is, where could the causes of the ignition timing retards lie?

Does anyone know anything about this?

Wait a few more kilometers.

Around 7500 km, check everything again.

mullemaus wrote:

Check everything again after approximately 7500 km.

Hmm... Are you referring to the mechanical break-in period of the engine (for every 2 Nm less of internal friction, the maximum power of a gasoline engine increases by approximately 1.5 horsepower)?
or does it rely on a hardware initialization function within the software that is deactivated after a certain number of kilometers?

Around 7500 km, check everything again. :wink:Hmm... Are you referring to the mechanical break-in period of the engine (for every 2 Nm less of internal friction, the maximum power of a gasoline engine increases by approximately 1.5 horsepower)?
or to a hardware initialization function of the software, which is deactivated after a few thousand kilometers?

The software function for initial setup.

Wow, my A4 with a 200 hp TFSI engine apparently consumes 16 liters per 100 km at 210 km/h, according to the display. Current consumption.

I think 30 liters is a bit too much. I drove the route from Leipzig to Braunschweig with an average speed of 138 km/h, and it consumed 13 liters of fuel per 100 km.

I find the TFSI surprisingly fuel-efficient under load.

By the way, even with E10 fuel and an outside temperature of 35°C, there is no reduction in ignition timing at maximum speed.

Hi,

I think you're talking past each other... Ulf, if I understand correctly, was referring to the instantaneous fuel consumption at FULL THROTTLE while accelerating to 200 km/h, not the fuel consumption required to *maintain* a speed of 200 km/h.

Best regards,

Jan.

Oh, in that case, that would be a rather strange statement.

I find it interesting that the TFSI engine takes the same amount of time to reach 210 km/h as my Passat TDI, which is basically a slowpoke. He was there in the end, that bgw crutch.

Here's the translation:

"Thinking about the Polo WRC, I also realize that the engine power isn't exactly excessive; it might already be at its limit in standard trim."

Benni wrote:

I find it interesting that the TFSI needs the same amount at 210 km/h as my Passat TDI, which is basically a slug...

16 liters per 100 km at 210 km/h as an instantaneous fuel consumption with a 2.0 TFSI? "Sorry, but based on my speedometer reading, I would only believe that if there were significant mitigating circumstances: downhill slope / tailwind / excessive speedometer reading, or a pronounced "dip" in the speed limiter's regular curve "
Or perhaps our TFSIs differ significantly in their design... Is yours possibly an EA888? They are supposed to run with a Lambda 1 setting, even with WOT (Wide Open Throttle), AFAIK.

Quote:

By the way, even with e10 fuel and an outside temperature of 35°C, there was no reduction in ignition timing at maximum speed.

Awesome!
I'll probably have to log the knock sensor voltage and cylinder-specific combustion data from two cylinders each for both engines. Perhaps this provides a clue to a problem with my engine...

EA113.

When I feel like it, and especially when I have the time, and when I'm not on my e-bike, I'll write you a log. It might take some time.

If he needed significantly more, I would have to stop more often to refuel on the almost 350km drive to the coast. I'm 16, or maybe 17, you can believe me.
The routes here are generally quite flat, and we don't have many mountains, if you exclude the Harz region.

I can't even get 30 liters per 100km, even at maximum speed (it's registered for 238 km/h, which it easily reaches according to the GPS), and right now, the current consumption is around 26 liters per 100km.

The speedometer, when using summer tires, is off by approximately 5 km/h compared to the GPS at a displayed speed of 200 km/h. So, (unfortunately), it's quite accurate.

Benni wrote:

EA113. Bitte gib den Text an, den du übersetzt haben möchtest. I can't even get 30 liters

with the car at its maximum speed (it's registered for 238 km/h, which it easily reaches according to the GPS), and right now, the consumption is around 26 liters.

Quote:

Then, our cars are probably not that different. The maximum my car shows is about 34 liters per 100 km, at 3000 rpm in 6th gear. If you keep your foot on the accelerator, the reading will decrease, and above approximately 200 km/h, it will drop below 30 liters. Mine is rated with a maximum of 350 Nm. "As far as I know, older 2.0 TSI engines had less torque. Perhaps that's also a difference between our cars?"

The 16, or maybe 17 liters, you can certainly believe me about.

Quote:

That can only be the average, if you're currently writing about 26 liters at @ Vmax. For a fuel consumption of 16-17 liters per 100 kilometers, I would have to drive aggressively and accelerate as much as possible in real-world highway traffic. In that case, the fuel consumption would likely end up being similar, but there are significant differences with the ZWR (presumably referring to a specific vehicle or technology).

The speedometer, when using summer tires, is about 5 km/h faster than the GPS at 200 km/h displayed. So (unfortunately), it's very accurate. Mine does the same: I simply adjusted the speedometer needle slightly so that the overestimation at 50 and 120 km/h is compensated, resulting in a difference of +/- 1 km/h.

Okay, so to reiterate: The current fuel consumption at 210 km/h is approximately 16 liters per hour during constant speed driving.

Tested on the Leipzig - BS tour (200km) with an average speed of 138 (before that, some city riding from the gas station to the train station and back home).
The cruise control was set to a constant speed of 210 km/h, which was the maximum speed my winter tires could handle.

Displayed fuel consumption: 13.1 l/100km (I still have photos of the FIS display from that trip).

The displayed value is adjusted and shows slightly more than the actual consumption calculated.

And correct, mine is specified with 280 Nm.

I'm actually very satisfied with the driving performance and fuel consumption. Okay, in the city, I never get below 10 liters per 100 kilometers, but I also can't maintain a fuel-efficient driving style for more than 50 kilometers in the convertible.

I once removed the spark plugs in the hope of finding clues related to the ignition system.
Previously, there was a rule of thumb that the insulator tip should be brownish in color, which indicated proper combustion.
Based on this, it seems my engine is running lean (see attachment). AFAIK, this increases the tendency for knocking, which in turn could explain the high specific wear rate.
Does that still apply to the 2.0 TSI engines?

My driving profile:
Mostly 2 x 20km per day, mostly country roads with several villages.
Approximately 50 km before I started modifying the spark plugs, I first drove him at a speed of around 80 km/h, as fast as traffic allowed, on the Autobahn, and on several occasions, I even exceeded 200 km/h.

"Fawn" used to be a common color, but these are mostly white.

Okay, then mine probably look normal.

I'm now focusing on the knock sensors and will thoroughly investigate them using logs, as best as I can. MWB 20 and 26 show the knock sensor reading (ZWR) and sensor voltage for all cylinders. In addition, providing information on parameters like engine speed, load, dwell angle, and total ignition angle, IMO offers a useful overview.
The initial logs, for example, show that even during a 3-second gear shift pause from 3rd to 6th gear (a drop in RPM from 6400 to 3000), the sensor voltages do not completely stabilize, even though the engine was running in full power mode. That seems a bit strange to me.

Unfortunately, the knock sensors are cleverly hidden behind the thermostat housing or the oil filter flange, which means that even a temporary replacement, or even just checking the tightening torque, involves a considerable amount of work .

If anyone has specific tips on how to detect an oversensitivity of the knock sensors, I would be grateful for any advice.

Hmm, I would actually like to wait and see. It's quite possible that there's still a break-in period involved, and that they're trying to avoid pushing it too hard at this stage. At the very least, it can be explained logically.

Unfortunately, I've never actually seen any of those programs. Always just vague hints like the one above.

There was definitely such a program for the 888, likely due to the variable oil pump. But it would be interesting to see what other effects it has.