Octavia 1U 1.8T power fluctuation

Hi,

I currently have a Skoda Octavia 1U, manufactured in 2001, with engine code AUM and a 1.8T engine producing 150 horsepower.
*** chip tuning, Forge SUV parts, large SMIC (intercooler), catalytic converter, exhaust system.

Error description: Performance fluctuations in the partial and full throttle range.

Already checked: all hoses, some replaced, Mass Air Flow sensor replaced with a new Pierburg, throttle body cleaned, turbocharger inspected, N75 valve checked, wastegate checked, pressure sensor and valve of the crankcase ventilation system replaced, fuel filter replaced, fuel pump replaced with a used one.

I once drove in third gear for a long distance. The temperature is a bit too low, the thermostat still needs to be replaced, but the error occurs at any temperature.

What do the experts say about the values? I find the injection time to be quite high already, but what else could be causing it?

Hello,

Quote:

Problem description: Performance fluctuations in the partial and full throttle range.

At what RPMs? Did those fluctuations also occur when you created the log you posted?

Please also log the engine load and lambda values, in addition to the air mass.

Best regards, Rainer.

The fluctuations manifest in various ways, and while they are minor, you can clearly feel that the engine is sometimes lacking a few horsepower during acceleration. However, if you continue to accelerate, it regains its full power.

They're always there, no matter which aisle you're in. Only at sometimes different speeds.

I've now replaced the pump with a new one, but unfortunately, that didn't solve the problem either.

I've now created two more log files, one with the Lambda learning rate and one with the factor. I wasn't sure which one you wanted.

The latter, learning rates, are less relevant for short-term phenomena because they represent averages.

"I can't see anything in your log. Do you not have a 'Turbo' button in your measurement blocks?"

What do ignition timing retard and misfire detection do? Autoscan?

I had to Google the "Turbo Button" to find out what it was, but no, it doesn't exist.
What is it good for?

I'm going to run an Autoscan right away.

Thursday, January 22, 2015, 19:06:09:02135
VCDS -- A Windows-based VAG/VAS emulator.
VCDS Version: RKS 12.12.3.0
Data as of: 20140904


Vehicle Identification Number: TMBGL21U012515xxx License Plate: LIUZTLUG
Mileage: 125,850 km. Repair order:
"Die Sonne scheint hell, und die Vögel zwitschern fröhlich. Es ist ein wunderschöner Tag, um spazieren zu gehen oder ein Picknick im Park zu machen. Viele Menschen genießen das gute Wetter und verbringen Zeit im Freien."

Vehicle type: 1U (1U - Skoda Octavia (1997 > 2011))
Scan: 01 02 03 08 15 16 17 19 22 29 35 36 37 39 46 56 76

Vehicle Identification Number: TMBGL21U012515xxx Mileage: 125,850 km
"Der schnelle braune Fuchs springt über den faulen Hund."
Address 01: Engine Control Module
Label file: RKS\06A-906-032-AUM.lbl
Part number: 06A 906 032 FC
Component: 1.8L R4/5VT 0002
Encoding: 11500
Operating number: WSC 31480
VCID: 64CD0ADCF453E83E1F5-5178
TMBGL21U012515xxx SKZ7Z0A0889320

No error codes found.
Readiness: 0110 1101

"Der schnelle braune Fuchs springt über den faulen Hund."
Address 03: Brake Electronics Label file: RKS\1C0-907-37x-ASR.lbl
Part number: 1C0 907 379 D.
Part: ASR FRONT MK60 0103
Encoding: 0021505
Operating number: WSC 31480 000 00000
VCID: 2B5FA1E0890D67461EF-515A

No error codes found.

"Der schnelle braune Fuchs springt über den faulen Hund."
Address 15: Airbag
Label file: RKS\6Q0-909-605-VW5.lbl
Part number: 6Q0 909 605.
Part number: 0L AIRBAG VW5 0B 0006.
Encoding: 12364
Operating number: WSC 31480
VCID: F4EDFA9CC4B3F8BE0F5-5178

Sure, here is the translation of the text from German to English:

"1 error found:"
00532 - Power supply voltage.
07-10 - Signal too weak - Sporadic.

"Der schnelle braune Fuchs springt über den faulen Hund."
Address 17: Terminal block module
Label file: RKS\1U0-920-xxx-17.lbl
Part number: 1U0 920 810 B
Component: COMBINATION INSTRUMENT + SPEEDOMETER VDO V05
Encoding: 03112
Operating number: WSC 47571
VCID: 2C5DA2FCDC03607E175-5178
TMBGL21U012515xxx SKZ7Z0A0889320

No error codes found.

"Der schnelle braune Fuchs springt über den faulen Hund."
Address 19: Diagnostic interface
Label file: RKS\6N0-909-901-19.lbl
Part number: 6N0 909 901.
Component: Gateway K<->CAN 0001
Encoding: 00006
Operating number: WSC 31480
VCID: F0E5F68CB0ABC49EEBD-515A

No error codes found.

"Der schnelle braune Fuchs springt über den faulen Hund."
Address 46: Comfort System
Label file: RKS\1J0-959-799.lbl
Part number: 1J0 959 799 AH
Component: 5N Central SG Comfort 0001.
Encoding: 04097
Operating number: WSC 31480
VCID: 840DAA5C9413C83E3F5-4B32

Subsystem 1 - Part number: 1U4959801B.
Component: 5N Throttle Controller. FS0002r

Subsystem 2 - Part number: 1U4959802B.
Component: 5N Throttle Controller. BF0002r

Subsystem 3 - Part number: 1U0959811B
Component: 5N Throttle Controller. HL0002r

Subsystem 4 - Part number: 1U0959812B
Component: 5N Throttle Controller. HR0002r

No error codes found.

Sure, here is the translation of the text from German to English:

End
--------------------------------------------------------------------

I've generated two more log files with fewer data points.
And that's when I noticed that every time I feel like I'm losing power, the injection time (before top dead center) is in the negative range within that approximate RPM range.

"Dropout detection is enabled, but 0 dropouts have been detected."
Ignition timing correction remains at 0.0.

edit @Autoservice: VIN fixed.

Your boost pressure control system is working (comparing target and actual values), but the air mass values seem relatively high to me, even considering the tuning.

Your engine control unit (ECU) is designed for an AUM engine with 110 kW. With a software modification alone, you can realistically expect to achieve around 180-190 horsepower. According to...
Okay, I'm ready. Please provide the German text you want me to translate.

Air mass (g/s) = Pmax(kW) * 1.1 (...) = 154 g/s at approximately 190 horsepower (140 kW).

Was was only the software changed, or was a different turbocharger installed as well?

You might be able to compare the boost pressure in your log with that of other similarly powerful 1.8T engines to see if it matches up.

In your log, the peak mass airflow value is 185 g/s. That means either there's a leak in the charge air system (hoses, intercooler, valves, etc.), or your vehicle should have more than 190 horsepower.
If air were lost due to a leak, the long-term adjustment values of the lambda control system would be significantly negative (less fuel would need to be injected than expected), for example, -20%. What values do you have in the corresponding measurement block?

Best regards, Rainer.

According to the documents and the registration information from the well-known tuner with 3 letters in its name, the car has 215 horsepower.
Unfortunately, I can't say for sure whether a different turbocharger is installed, but it wouldn't be unbelievable considering the other components that have been modified.

The intercooler piping is sealed; I've already checked that.

The boost pressure is a maximum of 1.3 bar, decreasing to 0.8 bar.

In which measuring range should I measure this?

Okay, 215 horsepower is equivalent to 158 kilowatts, which would result in an approximate air mass flow rate of 174 grams per second. It would be roughly within that range.

Is the "turbo" button a feature that's possible with your engine control unit?

What about the ignition timing retard in measurement block 20?

Are you sure it's not misfires? Please note that logs that don't contain information about "performance fluctuations" are unlikely to provide much insight into the reasons for those fluctuations.

Hi,
As mentioned before, there is no "turbo" button available, possibly due to the laptop being too old or because I am still using a serial adapter instead of a USB adapter.

Ignition timing retardation is always at 0.0, and misfires are also at 0.

However, these fluctuations are present with every acceleration.
There are still two other people who have experienced the same thing, and they have confirmed to me that I'm not imagining it.

As soon as I disconnect the LMM (lambda measuring module), it runs with slightly less power, but absolutely consistently without any fluctuations.

"Tomorrow, I'm going to borrow the boost pressure gauge and the wideband lambda sensor from my other car and connect them to this one, to see if I can detect anything."

Quote:

as mentioned before, there is no "turbo" button available, perhaps because of the old laptop or because I am still using a serial adapter instead of a USB adapter? Ignition timing retardation is always at 0.0, and misfires are also at 0

.
Okay, I guess it was a bit late for me.

No, the "Turbo" button should be there, as far as I know. Whether it is present or not depends on the specific control unit.

Since the boost pressure and air mass values initially appear to be within the normal range and there are no noticeable drops or other anomalies, using a wideband oxygen sensor would be a good idea for further troubleshooting.

Unfortunately, I haven't gotten access to broadband internet yet, but I quickly installed a boost pressure gauge this morning.

The values from the control unit seem very strange.
According to the boost pressure gauge, the boost pressure in overboost mode reaches slightly above 1.4 bar, then drops to 1 bar, then rises again to 1.3 bar, and continues to fluctuate.

Toshi wrote:

According to the boost pressure gauge, the boost pressure in overboost mode reaches slightly above 1.4 bar, then drops to 1 bar, then rises again to 1.3 bar, and then continues to fluctuate.

Fluctuating boost pressure in a gasoline engine practically inevitably causes corresponding torque fluctuations.
Roughly estimated:
Either there's a hardware issue related to the wastegate, or the boost control parameters in the software aren't as good as the ones your tuner uses.

Unfortunately, I haven't gotten around to getting broadband yet, but this morning I quickly installed the boost pressure gauge.

The values from the control unit seem very strange.
According to the boost pressure gauge, the boost pressure in overboost mode reaches slightly above 1.4 bar, then drops to 1 bar, then goes back up to 1.3 bar, and then continues to fluctuate.


1.4 would be far too much for a K03 / K03s...
Regardless of overboost.

The diagnostic values for the boost pressure look great. I wouldn't put too much stock in a mechanical boost gauge, especially with cheaper "canned" turbo kits.

According to the first log, it also only has a pressure of approximately 1 bar. If I remember correctly.
That doesn't mean it has 215 horsepower.

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

If the analog signal has dropped 20 times, then it's obviously faulty .