Engine RPM fluctuation starting at 3300 RPM (AVF), with log file!

Hello everyone,

"I've been reading the forum for a while now, and I'm having a problem with my Passat 3bg. The engine code is AVF, and it was manufactured in 2002. It's a 6-speed manual transmission. The mileage is currently 160,000 km, and it's been chipped for the last 70,000 km." I have never had any problems with the engine.

Okay, here's the translation:

"Here's the situation: When I accelerate and the engine reaches between 3300 and 3400 RPM, I experience extreme engine jerking. I used VAG-Com to check the data blocks 8, 10, and 11. During the jerking, there's a noticeable drop in both the smoke limit and the fuel injection quantity, but only for a very short time, about 1-2 seconds. The target boost pressure suddenly drops from 2500 mbar to approximately 1200 mbar, and then, about 2 seconds later, it returns to its full value." This causes the actual boost pressure to drop to 2300 mbar and then overshoot back up to 2800 mbar. I know that these values are a bit high. These values are only reached during the jolting/jerking.

I suspect that the newly implemented smoke reduction system is causing the engine to stutter. The LMM seems to be in order based on the values.

Does anyone else experience similar problems within such a narrow speed range?

edit: hmmm... it seems like no one can help me with my problem. I'm going to look for a web space now and then upload the log files.

Just to add some more information, the jerking doesn't occur when the engine has only been running for 10-15 minutes; it only happens after that. I just reactivated the EGR valve. Could it be because it was deactivated due to the vacuum hose?



bashful

hello also,
I have something very similar in my 2002 Touran.
When the engine is cold and running normally, it exhibits intermittent misfires at approximately 2500-3000 RPM when it warms up.
Temperature sensor and adapter cable kit replaced, but still no success.
I would appreciate suggestions for troubleshooting.
Best regards, auri.

hello,

Okay, in my case, it's not a gentle stuttering. I can only continue with a lot of throttle, and then the engine pulls through the problem area. After that, everything goes back to normal. There's absolutely no loss of power, except within that specific RPM range. Also, I've noticed that the status of the pump-injector elements is sometimes 4, not 0. Something doesn't seem right there. I'm still trying to figure out what it could be.

weblink log-file: http://www.filespider.info?file=2bf620c22ba6bffd71c0709ba9654212

Best regards, Schewisch.

Pressure sensor making a loud noise?

P.S. - The Touran must be a model from 2003 or later.

schewisch wrote:

At the moment of the jerk, there is a noticeable drop in both the smoke limit and the injection amount. This is only for a very short time, approximately 1-2 seconds. The target boost pressure drops sharply from 2500 mbar to approximately 1200 mbar, and then, about 2 seconds later, it returns to its full value. This causes the actual boost pressure to drop to 2300 mbar and then overshoot back up to 2800 mbar. I know that these values are a bit high. These values are only reached during the jolting/jerking. I suspect that the newly implemented smoke reduction system is causing the engine to stutter. The LMM seems to be in order based on the values.

Without looking at the logs:
I can only explain the simultaneous drop in opacity and LD Soll with a jumping pedal signal. Then the driver's preference would also have to apply to the basement...?
Next time, log MWB 8 and 10 simultaneously. The pedal position setting in percentage in MWB 10 provides an additional reference point.

hello everyone,

Pressure sensor? Then I'll have to tackle this.

@ulf: I logged MWB 8, 10, and 11 simultaneously. I also suspected that the accelerator pedal potentiometer might be sending incorrect information. I once tested it with VAG-Com, and everything seemed to be fine.

I specifically drove up a long incline on a highway, using full throttle in the highest gear. Then, at approximately 2500 RPM, I pressed the accelerator pedal to 100% and held it down, accelerating until the engine started to sputter. It seems the system always aims for 100% throttle! According to the log, that's what happened.

Could it possibly be related to the wiring harness of the power distribution (PD) units, even though there are no error codes stored?

Best regards, Schewisch.

What was the sampling rate of VAG-Com? It's possible that the jumping behavior was simply due to an insufficient sampling rate.

Hello and thank you.
The Touran could certainly be a 2003 or 2004 model, and it's definitely a 2.0L PD engine.
The error memory is empty. I cannot read measurement data blocks.
How does a faulty pressure sensor manifest itself in the engine? Does the Touran run mostly normally with the cable disconnected, or does it go into emergency mode?
Regarding the adapter wiring harness, that seems like a possible solution in the case of the Passat.
Regards,
auri

vagtuning wrote:

Is your pressure sensor making a loud noise? P.S. - The Touran must be a model from 2003 or later...

Hello,
The leading sentence leaves no errors in memory, but it would explain the partially missing status of the PD element.
Regards,
auri

schewisch wrote:

hello everyone, Pressure sensor? Then I'll have to tackle this. @ulf: I logged MWB 8, 10, and 11 simultaneously. I also suspected that the accelerator pedal potentiometer might be sending incorrect information. I once tested it with VAG-Com, and everything seemed to be fine. I specifically drove up a long incline on a highway, using full throttle in the highest gear. Then, at approximately 2500 RPM, I pressed the accelerator pedal to 100% and held it down, accelerating until the engine started to sputter. It seems the system always aims for 100% throttle! According to the log, that's what happened. Could it possibly be related to the wiring harness of the power distribution (PD) units, even though there are no error codes stored? best regards schewisch

hello,

Yes, that's right. The sampling rate is quite low; based on the log file, it seems like a value was only recorded every 1.2 seconds. I have to agree, a lot of information could be lost with that. Okay, I need to delve deeper into using VAG-Com. The sampling rate is also highly dependent on the control unit and the amount of data being transmitted.

@ulf: Maybe you could take a look at the files? I don't understand why the smoke limit is being enforced, the torque limit remains at the top, the fuel injection amount is decreasing, and the LD (likely referring to a specific parameter) should also...

Best regards, Schewisch.

Today, I drove again, and the jerking/shaking was gone. Okay, it won't be fixed, but I'll try swapping the adapter cable kit to the PD elements on Saturday.

Is that part number 038 971 600? It should be compatible with AKTE for engines AVF, AWX, and AVB.

As soon as my laptop is working again, I'll go for another logging trip.

bashful

schewisch wrote:

@ulf: maybe you could take a look at the files? It seems that the smoke limit is being applied, the torque limit remains at the top, the injection amount decreases, and the LD should also... I don't understand.

I've prepared the log data graphically in a slightly different way. The most peculiar thing is the drops in the actual LD value, even though the TV (throttle valve) didn't command any reduction. To compensate, a counter-steering action is applied in the direction of "LD high," which then causes oversteer.

Along with the other erratic behaviors, this seems like an issue with the electrical/electronic system, specifically either the 12V main power supply or the 5V level of the MSG (Main System Generator).
We haven't had any issues with relay 109 for quite some time now...

hello,

ulf, thank you very much for your analysis. I just got home and will take a look at the diagram tomorrow. I'll also check the relay right away. I recently had a faulty alternator where the freewheel was stuck, which caused it to spin at extremely high speeds. It's possible that I had significant voltage fluctuations in the vehicle's electrical system.

Best regards, Schewisch.

Hi,

I once had a similar vehicle with the same symptoms, and it took me a very long time to find the cause.

The problem was a defective or loose speed sensor ring on the crankshaft. You can check this by removing the speed sensor and then feeling with your finger to see if the speed sensor ring moves. Of course not with the engine running.
If it moves like that, you've found your mistake.

It took me quite a while to find the problem back then. In the end, the customer went to VW and got a new engine under warranty, but he had to pay for the installation. According to VW, the timing ring on the crankshaft is riveted on. I haven't personally inspected it yet, so I can't say much about it.

Best regards, Germa.

germa wrote:

The error was a defective/loose speed sensor ring on the crankshaft. . . It really took me a while and a lot of frustration to find the error back then. In the end, the customer went to VW and received a new engine as a goodwill gesture.

Wow, you have to really think outside the box to come up with that.
Did the problem only start "sometime" ago (like with Schewisch), or was it present from the beginning and only delayed beyond the warranty period as a matter of "state of the art"?

@schewisch: It would also be interesting to see if the drops in LD (likely referring to a specific measurement or value) are also visible on an LDA (likely referring to a different measurement or analysis method).

hello everyone,

@germa: Oh dear, I see I have a lot to do on Saturday. I'll make my way through to that sensor.

@ulf: I'm already starting to gather the parts for the LDA. I've now managed to get a small pressure gauge and some pneumatic tubing from Festo. I saw on your Polo that you tapped into the AGR valve for it. It looks good, but can I quickly tap into the LD signal somewhere else for testing, without having to drill a hole in the chassis?


The problem now occurs sporadically. Sometimes I can accelerate smoothly, but yesterday, while driving on the Hunsrück Höhenstrasse, I was overtaken by a truck.

edit: According to my VW service center, this relay is not available for my Passat. Model: 3BG, Engine: AVF, Year of manufacture: 12/2002?

Best regards, Schewisch.