Octavia 1U 1.8T Leistungsschwankung | Posts 16+

Take a look at the "injection time" in Log 4: it's fluctuating wildly, is that normal?
What size is actually being displayed there?

Quote:

An analog display is different from an electric. The sensor is becoming more and more accurate. The error rate alone is lower.

I believe that's just a rumor about the analog hair straighteners that are supposedly sold commercially (especially those from "Ching-Chong Land").

The common boost pressure sensors are equipped with...

Quote:

Accuracy: ±0.25%

specified, meaning that at an absolute pressure of 2100 mbar, the error is +/- 5.25 mbar. Even with potential quantization effects, the deviation will still be less than 10 mbar.

"Show me the Ching-Chong can, and what it can do - besides, you wouldn't even be able to read such small changes."

Perhaps your post was intended to be ironic.

Is that a Racimex ad? It seems to be quite accurate.
But the turbocharger boost pressure seems to be doing whatever it wants.

I was briefly called to the highway today, driving in the 5th gear with full throttle. The road to Gang is terrible to drive on.

I'm going to order another N75 now. I'm slowly running out of ideas.

Where exactly is your Racimex sensor connected, and where is your boost pressure sensor located?

An analog display is different from an electrical. The sensor is becoming more and more accurate.
The error rate alone is lower.
I believe that's just a rumor about the analog hair straighteners that are supposedly sold commercially (especially those from 'Ching-Chong Land').

The common boost pressure sensors are equipped with...
Accuracy: ±0.25%
specified, meaning that at an absolute pressure of 2100 mbar, the error is +/- 5.25 mbar. Even with potential quantization effects, the deviation will still be less than 10 mbar.

'Show me the Ching-Chong can, and what it can do - besides, you wouldn't even be able to read such small changes.'

Perhaps your post was intended to be ironic.

No, I'm serious. Before I trust a sensor reading, I'd trust an analog display. And I mean 'standard' ones, like those made by VDO or similar manufacturers.


Why? If someone is tinkering with the car and haphazardly swapping parts, it's possible that boost pressure sensors could be 'swapped incorrectly.'


'They're all the same, and he fits in just fine.'


The results are: Displayed value in VCDS: 1 bar, actual value: 1.5 (values are fictional).
This is what happens when you replace a sensor with a different pressure range, for example, changing from a 200/250 kPa sensor to a 300 kPa sensor.


This isn't necessarily the problem here (well, almost), but here's an example from real life.
It doesn't matter if the analog displays are accurate to 0.1 bar. You can generally tell whether what was 'supposed' to be implemented through programming has actually been done.


I was briefly called to the highway today, driving at full speed in 5th gear. The Gang is a terrible car to drive.

What injection timings were available at that time?
Are the speaker wires connected correctly (FOR SURE!)? Is the fuel pressure regulator okay and not broken? (Take it out and check it.)
Are all the hoses/lines, especially those located under the intake manifold, in good condition?

I'm going to order another N75 now. Slowly, I'm simply running out of ideas.

Is this the standard version or the 'enhanced' version?

Quote:

No, I meant that seriously. Before I believe a sensor, I believe an analog display. And I mean "standard" ones, like those made by VDO or similar manufacturers. Why? If someone is fiddling with the engine and haphazardly swapping parts, it can happen that boost pressure sensors are "swapped incorrectly."

Okay, you are naturally right about that.

Here's something from me again.

I have now replaced the N75 valve with a new one.
The old one was an N75 "F", and the new one is also an N75 "F".
The pressure fluctuations up to 1.4 bar are gone; the boost pressure remains relatively constant at 1.1 bar and drops to 0.8 bar. For that, the car has slightly less maximum power.

I also once swapped the fuel pressure regulator with another 3-bar unit from my VR, but there was no change.

The hoses are DEFINITELY correct.

I've created some more logs.
What still strikes me is the injection time, which is now sometimes as high as 27ms!!
An original, unchipped unit has a latency of 16ms, while a chipped unit should not exceed 22ms.

In the first log, the injection time confirms my feeling: the power fluctuates at full throttle. Above 4800 RPM, it pulls freely, and the injection time decreases and remains constant.

2. Only MWB002 and 003 were logged, maintaining the same conditions.

Both are in the 5th lane on the highway.

3. Log 3. Main road with traffic signs MWB 002.003 and 033.

I've also checked the boost pressure and throttle/pedal position, but everything seems normal.
Since the turbocharger pressure is now correct, the problem must be with the fuel, but where exactly?
It can probably only be a problem with the nozzles.

Hello,

If I were in your position, I would first try to figure out where the different pressure readings (diagnosis vs. mechanical gauge) are coming from.

Quote:

Since the turbo pressure is now correct

Previously, according to the log, it was also working correctly.

Perhaps Mullemaus is not entirely wrong, and the car is a poorly assembled, amateurish tuning job.

Has that vehicle ever worked properly for you?

Best regards, Rainer.

The boost pressure remains relatively constant at 1.1 and drops to 0.8 bar.

I would consider that to be OK.


'Log 99' looks okay except for the relatively high injection times.
Air mass for standard hardware, producing approximately 205-210 horsepower.

'Log '88' also looks good.' Air mass rising again.
Okay, except for the relatively high injection times.


What I still notice is the injection time, which is now sometimes as high as 27ms!!
An original, unchipped unit has 16ms, and a chipped unit should not exceed 22.

This statement is nonsense. The final injection times depend on the injector size, its utilization rate, as well as factors like fuel supply and the functionality of the components.

An old or used fuel pump, for example, will hardly help if both of them are empty.

You can try replacing your BDR (part number @ 037133035C) with a 4 bar unit (part number 078133534C) for testing purposes; it should provide approximately 8-10% more boost. If the injection times improve, then you have a supply problem.

Pump/filter. And no, a used pump is not a reference.