Sch.....rott Elektronik im Auto | Posts 96+

My colleague finally took his Skoda Octavia Combi through the roundabout.

Unfortunately, the result was the same disappointing one as with his Passat.

If he slightly increases the speed, the vehicle will eventually start to understeer. If he continues to hold the steering wheel in the desired direction, nothing will happen... except that he will eventually hit the guardrail.
As soon as he turns the steering wheel, the ESP kicks in immediately. It's so aggressive that the car suddenly swerves sideways.

Interestingly, the ESP kicks in and pushes him off course at around 55 km/h.
Without ESP, he managed just over 65 km/h. It was possible to correct it with the steering and accelerator, but still. Apparently, he still has some old software installed.
He continues to rely on his security training.

CU Gremlin.

@ Bertil


I actually tried the same thing with my A4 in the snow the other day, and it worked amazingly well.
I'm really impressed with the combination of ABS/ESP/EDS.

What surprised me even more negatively, however, was...
The engine brake is no longer working, at least not with the diesel engine.
After pumping 3-4 times, there is absolutely no vacuum pressure left for the brake booster .

@Bertil:

Did you have Contiteves installed again, or did you get Bosch this time?

Good question. I haven't checked yet .

Hm, that would actually be quite interesting, could you perhaps take a look at that?

Okay, let's dig up that dusty post from the archives...

@Bertil:

Yesterday, I finally had the chance to thoroughly test the ESP (An empty, tarred, and completely snow-covered parking lot, about the size of 2 soccer fields), and I have to say that it reacts exactly as expected. The 8E has a heavier rear end with more overhang (compared to the Golf 4), but it really takes a lot of effort to get it to lose traction. Rear drifts like the ones I used to get with my old Golf 4 and the handbrake are almost impossible to achieve now, because the rear end stabilizes so quickly that you don't really have to do much, and it automatically corrects itself and gets back on the desired trajectory.
Even during steering tests (slalom) at approximately 50 km/h and with the handbrake firmly engaged (pulling the HA), the car is so easily controllable that it becomes boring.

Okay, let's talk about ESP:
It reacts to both the steering speed (steering wheel) and the steering angle with varying degrees of force. If you drive straight and simply turn the steering wheel to a certain point, then hold it steady, ESP will continue to engage until the car follows the steering angle. If you continue to turn the steering wheel all the way to the stop while the car is understeering, the intervention will be stronger. I was unable to confirm your experiences that ESP doesn't react at all when the steering wheel is held steady. The condition of sliding will be detected with 100% accuracy.

Even when taking a curve at approximately 50 km/h and suddenly engaging the handbrake, the ESP reacted so excellently and quickly that the rear of the car didn't slide out at all. The Golf would have definitely spun out at least 180 degrees here without ESP.

What I particularly appreciated was that the ESP system first effectively reduces the vehicle's speed before it starts to correct the direction. It's better to stand still than to have the cart slip.

Furthermore, the ESP quickly adjusted to the varying friction levels (some larger tar spots remain on the parking lot from cars that were previously parked there without snow), and even with full intervention, it did not cause any instability at the rear. The first ESP systems at Mercedes-Benz experienced an increased number of issues with this problem.

I initially thought the torque limiting feature was a pointless gimmick, but it actually works very well and provides better contact between the wheels and the ground. The rear also doesn't bounce up excessively during braking, and the ABS doesn't activate too aggressively (which means the rear axle isn't unloaded as much).

It was also interesting to note that when the ESP was manually deactivated, it only engaged when a panic braking maneuver was initiated. If normal braking was applied, the ESP did not activate. Generally, with Mercedes-Benz vehicles, touching the brake pedal reactivates the ESP if it had been previously turned off. At Audi, probably only in emergencies.

In various attempts to deliberately induce understeer, the ESP system repeatedly corrected the vehicle's trajectory to maintain the desired direction of travel. It was not possible to 'dispose of' the car, and no malfunction could be detected.
However, a significant advantage is also the ContiTS790 tires, which I am now using in size 205/55/16/H, unlike the Golf4. The traction is roughly the same as that of 195/65/15/H tires, but the lateral grip is significantly better.

Hi Julian,

This weekend, I checked the manufacturer of the ESP control unit again: Contiteves.

Julian wrote:

What particularly impressed me was that the ESP first effectively reduces the vehicle's speed and only then focuses on directional correction. It's better to stand still than to have the cart slip.

... To the dismay of those following behind... the brake lights don't even come on! Whoever is driving behind you and doesn't expect an ESP intervention will be right on your tail.

That's correct, and it's good that the ESP effectively reduces the vehicle's speed. Because the best and most effective way to stabilize is still to drive slowly !

I can't get the rear end to stop wobbling, even with the handbrake. The ESP system is very good at detecting such drastic interventions in the driving process.
I was referring to load transfer reactions that can lead to a sudden loss of rear grip. These (relatively slow) processes are not detected well or quickly enough by the G4 ESP system. The type of surface doesn't matter.

Otherwise, your descriptions exactly match what I've also observed with my ESP.

Hi Bertil!

The oversteering of the rear wheels was immediately corrected. The rear of the vehicle was brought into a sliding motion on the asphalt, then steered into the curve, while encountering snow. There was an immediate reaction.
It simply wasn't possible, even though you were riding aggressively in a high gear, which would normally relieve the rear tire.

The brake light issue could potentially lead to problems, but normally, in winter conditions with ESP engaged, you have enough space to react. Or at least, one should have it.
Rear-end collision due to ESP system malfunction... that would be a headline.

Julian wrote:

The oversteering of the rear wheels was immediately corrected. The rear was brought into a swinging motion on the asphalt, then steered into the curve, and in this process, encountered snow. There was an immediate reaction. It simply wasn't possible, even though you were riding aggressively in a high gear, which would normally relieve the rear tire.

So, in this situation, the Audi ESP system reacts significantly differently – and better.

Quote:

The brake light issue could potentially lead to problems, but normally, in winter conditions with ESP engaged, you have enough space to react. Or at least, one should have it. Rear-end collision due to ESP (Electronic Stability Program) malfunction... that would be a headline.

(Auto) Bild initially spoke with those affected .....

@Bertil:

What do you actually think, could the entire issue be related to the vehicle's suspension system? Deeper and harder is probably better?
The standard Golf4 FW had left me with a somewhat dubious impression, as it allowed for a high but rather narrow tolerance range. With the Eibach ProKit, the suspension was definitely better; it provided more feedback and indicated changes in direction earlier.

What do you think about it?

by the way
Does your Golf 4 steering also become a bit stiff when the rear end starts to slide? 'He always had something going on...'

Hi,

Julian wrote:

What do you actually think, whether this could be justified from a technical standpoint regarding the vehicle's chassis and suspension.

Certainly, the FW has had a significant influence. It's possible that the intervention thresholds are the same, but the G4 sensor loses rear-end grip slightly earlier, which means the system's response is too late for the driving situation.

Quote:

Deeper and harder is probably better?

You know that I have the crocheted "Klopaierrolle" lying on the hat shelf...
Deeper, wider, harder is nothing more for an old man like me...

Quote:

The standard Golf4 FW had left me with a somewhat dubious impression, as it allowed for a high but rather narrow tolerance range. With the Eibach ProKit, the suspension was definitely better; it provided more feedback and indicated changes in direction earlier. What do you think about it?

For me, the FW is actually okay, despite its "tendency to oversteer." The rear end isn't a problem for me, as I'm familiar with similar reactions from rally cars. Otto Normalfahrer (the average driver) hopefully won't find himself in such driving situations, so it's not really a problem.
FW modifications (especially stabilizer kits like the Eibach Pro Kit) definitely have their merits. Especially with the station wagon, the front axle is a bit too soft compared to the rear axle, which is why there's a tendency to oversteer. The Pro Kit stiffens the body roll somewhat, which also makes the rear more stable. It might sound strange that a change to the VA (variable air volume system) actually makes the HA (heating, ventilation, and air conditioning system) quieter, but it's really true.

Quote:

by the way Does your Golf 4 steering also become a bit stiff when the rear end starts to slide? He always had something...

No, I haven't observed that yet.

leolotus wrote:

@ Bertil What surprised me even more negatively, however, was... The engine brake is no longer working, at least not with the diesel engine. After pumping 3-4 times, there is absolutely no vacuum pressure left for the brake booster

.

What you're doing is very dangerous!!! ABS is your stutter brake!
If you brake too hard yourself, you'll confuse the ABS system because the control unit won't know whether you're trying to brake or not. In extreme cases, you may have little to no brake force amplification, or the amplification may increase very slowly.
When driving on a slippery surface, brake gently to avoid locking up a wheel (you'll feel this as a pulsing in the pedal). Then, apply full brake pressure, and the rest will be handled by the ESP/ABS system.

What you're describing only works without ABS, in order to prevent skidding and maintain steering control (within limits).

davidshoes wrote:

The ESP/ABS system handles the rest.

That would be nice.
However, even if the ABS malfunctions, it can only reduce the pressure in the brake hydraulic system; the brake booster operates independently of this. Or have I missed the latest trend?

Vehicles equipped with EDS (Electronic Differential Lock) and/or ESP (Electronic Stability Program) have a hydraulic oil pressure reservoir. This serves as a "brake pressure reserve" during rapid braking interventions. The ABS system in these vehicles also utilizes this technology.

Generally speaking, if the ABS starts to engage aggressively, increase the pedal pressure as much as possible. Only in this way can a fast response time for the ABS be achieved.

Simplified control process:

Brakes engaged --> Wheel locks --> Relief valve opens --> Wheel rotates again --> Relief valve closes --> Brake pressure increases again, speed is regulated by the system pressure on the pressure side, which is generated by pedal pressure with the help of the brake booster (and with the help of the pressure reservoir, which allows for a faster response).
If the brake pedal is repeatedly and forcefully depressed while the ABS system is engaged, the vacuum in the brake booster may not be sufficient, and the pressure reservoir may become completely depressurized. Additionally, the vacuum hose connecting to the brake booster can become porous, leading to a loss of vacuum and reduced braking performance. Such defects should be repaired as soon as possible.

Vehicles equipped with pressure accumulators can draw braking force assistance from this source for 2 to 3 braking events even when the engine is not running. Without it, the vehicle brakes like one without power assist.

What do you actually think, could the entire issue be related to the vehicle's suspension system? Deeper and harder is probably better?

I've now adjusted the tire pressure based on the values from my weighing.

soll: V 2.0 H 2.2

Given that the front axle carries 840 kg and the rear axle carries 560 kg, that seems quite extreme.

I've now set the initial values to 2.2 at the front and 2.0 at the back (which is the opposite), which also corresponds to my experience from the start.

-> The handling is significantly improved, especially the rear end, which is now much more stable and less twitchy.

I'm putting forward the hypothesis that these unusual product specifications might also be contributing to the low price.

CU Gremlin.

Wow, dude... you've really been experimenting... straight to 0.2 bar!

Your rear end has been relaxed, which simply means it understeers more, right?

According to the manufacturer, my winter tires can handle a total pressure of up to 3.5 bar, which gives me a wider range to experiment with.
In the Golf 4, I drove with around 3.0 bar of oversteer, but mostly all around, because I prefer oversteer to understeer.

In the 8E, the tire pressure is currently 2.7 bar (the factory specification is 2., because the suspension is already very stiff and the tires have a smaller profile (55 instead of 65) compared to the Golf.

Wow, man... you've really been experimenting... 0.2 bar right away!

Sure... with the scooter, I can even notice deviations of 0.1 bar very clearly.
You just have to drive more on country roads, not just in the city and on the highway.


Your rear end has been relaxed, which simply means it understeers more, right?

No, he's now saturated and is covering all the ripe areas, so he's drifting nicely.


In the Golf 4, I drove with around 3.0 bar of oversteer, but mostly all around, because I prefer oversteer to understeer.

'No way. Anything above 2.5 bar when the vehicle is unloaded is just terrible; it drives like a torture device. I've experienced that firsthand (even with the 'box' - referring to a specific vehicle). The return trips with an empty load were... amusing.'

CU Gremlin.

:
The ABS II, introduced in 1993, received essentially only one major improvement. Here, the drive of the plunger was replaced by a motor with an electronically controlled clutch. Furthermore, the stroke of the piston (plunger) is now measured to ensure free rotation of the wheel. This measurement electronics is of enormous importance. By monitoring the piston position required in each situation, the ABS 2 system is now able to recognize the ideal braking pressure and maintain it for a longer period. In a way, the system "learns" the road surface conditions (dry, damp, wet)http://www.gdv-ifm.de/projekt/16799.htm and is therefore able to provide safe braking with the greatest possible deceleration.achieve. The ABS 2 system adds 7 kg of weight to the motorcycle.

Does something like that exist, and if so, since when, or which version, has it been implemented in passenger cars?