Performance loss and no one knows what to do

Hello everyone,

I'm new to this forum and I hope someone can give me some helpful advice because I'm really starting to feel desperate.

I drive a Golf IV TDI with 110 kW (ARL engine, manufactured in December 2002) that has been chipped to produce 130 kW. For the past few months, I've been experiencing a loss of power. My car isn't really fun to drive anymore, and I just don't know what to do.

Am besten fange ich mal ganz von vorne an. Der Wagen wurde von mir immer warm gefahren und nie kalt getreten und war auch bei allen Inspektionen. Bei 72000 km entschied ich mich das Auto chippen zu lassen. Das Auto lief super. Vom Fahrgefühl war es wie ein neues Auto. Bei 85000 km stand dann eine große Inspektion an, bei der auch der Zahnriemen gewechselt wurde. Das war im Januar 2006. Ich ließ damals auf eigene Verantwortung 0W-20 Öl von Fuchs einfüllen, welches keine VW Freigabe hat. Ich holte den Wagen aus der Inspektion ab und er fuhr sich irgendwie anders als vorher. Er fuhr sich weicher. While driving on the highway in fourth gear and with full throttle, the clutch would occasionally slip for about 3 days, but then it suddenly disappeared again (possibly due to temperature-related factors?).. Seit dieser Inspektion hörte ich auch ein hochfrequentes Pfeifen bei Vollgas aus dem Motorraum. Was sich noch verändert hatte war das Verhältnis zwischen Drehzahl und Geschwindigkeit. Früher hatte ich bei 180km/h im 6. Gang 3000 Touren und nun sind es 3200 Touren. Außerdem sackt beim Anfahren im ersten Gang die Motordrehzahl ab und pendelt dann so zwischen 800 und 1000 Touren hin und her. VIn terms of performance, everything was fine, so I stopped worrying about it altogether.

Bei einem Stand von ca. 90000km ließ ich nochmals den Ölfilter und den Kraftstofffilter erneuern. Seit dieser Zeit fehlte dem Motor dann die Leistung, was für mich eher wie ein unerklärlicher Zufall erscheint. Es fehlte Leistung in allen Drezahlbereichen und der Dieselwumms war auch futsch. Anfangs dachte ich erst es sei Einbildung, doch die Leistung ließ immer mehr nach, bis ich dann mit geschätzten 90 PS durch die Gegend tuckerte und gar keinen Durchzug mehr hatte. Noch ein neuer Kraftstofffilter brachte keine Abhilfe. Bin dann bei VW gewesen und die haben Ladedruck ausgelesen, welcher viel zu niedrig war. Habe dann mit einem Bekannten in einer freien Werkstatt das Auto mal angeschaut. The intake air passages were full of oil (it was dripping onto the underside of the engine).eckung) und die Welle vom Turbo hatte etwas Spiel. Ich war froh, dass wir den Fehler endlich gefunden hatten. Der neue Lader war zwar teuer, aber ich hoffte nach dem Einbau sei alles wieder in Ordnung. Leider war dem nicht so. Der Durchzug mit dem neuen Lader ist zwar wieder besser, aber immer noch nicht so wie früher. Von unten raus geht garnix. Früher habe ich den ersten Gang nur ein bisschen antippen müssen und es kam richtig Druck. Jetzt muss ich das Pedal vergeblich nach unten treten, damit überhaupt was kommt. Das hochfrequente Pfeifen war erstmal weg, kam aber nach ein paar Tagen wieder, so dass ich wieder Angst habe das mir der neue Lader auch noch kaputt geht. We then tested a new mass airflow sensor (MAF) and removed the air filter, but that didn't... leider auch nichts gebracht. Ich war dann nochmal bei VW, weil die freie Werkstatt nicht mehr weiter wusste und auch nicht die Messmöglickeiten hat. Dort wurden Ladedruck, Ladeluftschläuche, LMM, Ladedruckmagnetventil überprüft und natürlich zum zichsten Mal der Fehlerspeicher ausgelesen, der leider keinen Fehler anzeigt. Es war alles in Ordnung. Die haben dann alles aufs Tuning abgewälzt und das sie da leider nichts mehr machen könnten. In der freien Werkstatt haben wir gestern nochmal die Nockenwelleneinstellung gecheckt und verstellt, was allerdings auch keine großen Veränderungen brachte. II also can't imagine that everything was caused by the 0W-20 oil, since I previously had 0W-30 longlife 2 in it, and the 0W-20 was put in during the engine replacement by [Lo - presumably a person or company].I have replaced nglife 3.

As I said, I'm slowly reaching the end of my financial resources and my nerves are frayed.

Here's a brief overview of the following errors:

1. Lack of power across all RPM ranges. Occasionally, almost normal power is available for a very short period.
2. The engine speed drops when starting and fluctuates up and down.
3. High-pitched whistling sound coming from the engine compartment.
4. The relationship between speed and RPM is no longer correct.

Parts inspected: air filter, fuel filter, mass airflow sensor (MAF), wastegate solenoid valve, turbocharger, intercooler piping, camshaft.

I hope I haven't forgotten anything.

I am grateful for any advice you can offer.

You won't get very far without VAG COM... we need logs... But: what kind of tuning was it? Was it done via OBD? If so, the VW system might have installed a new "firmware" and overwritten the OBD tuning.

But how exactly do you envision the relationship between speed and revolutions? If a certain gear has 'x' revolutions resulting in a speed of 'y', then that remains constant. Only components are installed between the engine and the wheel that don't inherently change this gear ratio. The clutch cannot slip continuously; I would rule that out.

What makes this oil so special... but I don't think that's the problem.

It sounds more like a problem with the LMM (mass airflow sensor) or connection issues between the LMM and the MSG (engine control module). There might also be a leak in the diesel line near the filter (were the seals replaced?). It's worth checking the precise timing after replacing the timing belt, but not by just any VW mechanic.

Hi,

Thank you for the response.

The tuning was done via OBD. However, when I asked the tuner if Volkswagen could overwrite anything related to it during an inspection or similar, he told me that this was not possible.

The thing about the RPM relationship is really strange, I know. But before, I had 200 fewer revolutions at all speeds, regardless of which gear I was in.

The oil is a brand new, high-performance product that was just released on the market, and I had initially hoped it would result in slightly lower fuel consumption, but that's not really the point of why I had the oil changed back then.

Yes, the seals on the fuel filter were also replaced.

The valve timing should have been correct after the timing belt replacement, as the engine still had its power afterwards.

mecky wrote:

At that time, I had 0W-20 oil from Fuchs filled in, at my own risk, which does not have a VW approval.

Hi,

as a supplement to Matthias' answer:
Perhaps you damaged the positive electrode displacement (PED) components (or their actuators) with that oil. Oils specifically approved for PED systems are designed to withstand those particular and extreme stresses, while other oils may not be.

Otherwise: Read articles about performance issues and common mistakes .

Quote:

The tuning was done via OBD. However, when I asked the tuner if Volkswagen could overwrite anything related to it during an inspection or something like that, he told me that this was not possible.

That's nonsense unless the tuner implements specific measures to prevent reflashing (which is possible, but as far as I know, it's rarely done).
The fact that the RPM-to-km/h relationship has been changed already indicates to me that some software is different now.

Hi Ulf,

I've read the article several times, but I haven't found a real solution.

mecky wrote:

I have read the article

several times, but I haven't really found a solution.
Is it ensured/verified that the charging chamber actually receives a vacuum to initiate the lifting process?

Has the fuel pressure (at the outlet of the tandem pump) ever been measured? The erratic engine speed suggests a fuel problem to me, possibly also a faulty high-pressure injector (see above).
What amount of fuel does the EDC believe it should inject at idle (read from MWB 1)?
What do the idle speed control, PDE switching times, and PDE status indicate (according to sections 13, 18, and 23 of the manual)?

So, back then the tuner messed around with something in the fuse box and then told me that Volkswagen couldn't overwrite it.

Of course, none of those things were measured. The problem is that if I take my car back to VW now, it will cost me a lot of money, and they probably won't find anything. Unfortunately, I don't have the means to carry out such measurements myself. I need someone who's really knowledgeable about diesel engines who can help me, and I would, of course, pay them for their time. Right now, I can't afford a VW workshop.

mecky wrote:

So, the tuner had messed around with something in the fuse box back then and later confirmed to me that VW couldn't overwrite it.

Well, I don't quite believe it... depending on the car, you might simply need to pull a fuse in order to flash the software; otherwise, it won't work.

Quote:

I'm looking for a real diesel mechanic expert who could help me with something, and of course, I would pay them for their time.

Perhaps someone lives near you, but to find out, we first need to know your region.

Quote:

I currently can't afford a VW workshop,

and I don't want to.
Here's another case where having your own diagnostic equipment is probably cheaper than the next visit to the repair shop .
Take a look around our diagnostics shop .

I live near Frankfurt am Main. Maybe there's someone in this forum who would be willing to help me out.

mecky wrote:

I live near Frankfurt am Main. Maybe there's someone here in the forum who would be willing and happy to help me.

Your case seems interesting to me... if you were willing to travel all the way to Saarland, I would take a look (but with no guarantee of success!).
For details, please send me a private message.

One more question regarding error localization:

Do you experience a significantly reduced overnight power consumption compared to the average display?
Then a fuel supply problem (pump, pressure drop issues?) that is not monitored by the EDC becomes more likely...

Hi Ulf,

"The other day, when I filled up my car, it took 55 liters instead of the 50 liters that my calculations suggested. That was quite surprising. So, currently, the values calculated by my onboard computer regarding how much fuel I should need to fill are rarely accurate and don't usually match the actual number of liters dispensed at the pump."

I don't quite understand your question. What do you mean by "night refueling consumption"?

mecky wrote:

So, the values I've calculated based on the car's computer regarding how much fuel I need to add rarely match the actual liters displayed at the pump. I understand your question, but I don't quite follow. What do you mean by "Nachtankverbrauch"?

The amount of fuel added / distance traveled, multiplied by 100, compared to the average display on the multi-function instrument cluster (MFA).

Severe fuel supply shortages manifest themselves in the fact that after driving a certain distance, you don't need to refuel with the usual amount (15 liters per 100 km, as required by the manufacturer), but only 8 liters per 100 km (a random example), resulting in very poor performance.

It seems that is not the case for you, but rather the calculated injection amount probably corresponds roughly to the actual consumption.

Is the approximately 10% difference between the MFA (Multifunction Display) and the fuel level reading after refueling possibly related to the discrepancy between the odometer and the displayed mileage?

At that time, I had Fuchs 0W-20 oil filled, at my own responsibility, which does not have a VW approval.
Hi,

as a supplement to Matthias' answer:
Perhaps you damaged the positive electrode displacement (PED) components (or their actuators) with that oil. Oils specifically approved for PED systems are designed to withstand those particular and extreme stresses, while other oils may not be.

Otherwise: Read articles about performance issues and common mistakes .


The tuning was done via OBD. However, when I asked the tuner if Volkswagen could overwrite anything related to it during an inspection or something like that, he told me that this was not possible.
That's nonsense unless the tuner implements specific measures to prevent reflashing (which is possible, but as far as I know, it's rarely done).
The shifted rpm-km/h relationship already indicates, in my opinion, that some software is different now.

I think Ulf is right that the software doesn't fit his idea.
The engine speed comes from the MSG (presumably a control module). The speedometer signal comes from the instrument cluster. Since nothing mechanical can change in the transmission, this means that the engine speed is no longer being correctly detected or processed by the MSG. This could be a software problem.
It would be interesting to check the crankshaft speed sensor. If it's defective, the engine should only run in a limited mode.
Ask your tuner if they can re-flash the complete tuning file for you; maybe that will fix it. (Most reputable tuners do this free of charge when there are issues with reflashing.)
The boot protection is nonsense (as Ulf said). He removed the fuse because there are problems with the immobilizer when flashing the device using a specific tool. By removing the fuse, the immobilizer can be deactivated, which allows the flashing process to proceed.

What's supposedly so great about a 0W20 oil? The thermal stability is significantly weaker than that of a 0W30, so it's more likely to be counterproductive.
This could definitely overcook your pasta dishes.

Best regards, Jochen.

Hi,

"I'm actually using slightly more fuel than the onboard computer indicates. It's usually about 0.4 liters more than what's shown on the display. I can't say for sure whether this is related to the discrepancy between the rev counter and speedometer readings."

Having the tuning software reinstalled would be quite a task, because it would involve a long trip.

mecky wrote:

So, I actually use slightly more fuel than the onboard computer indicates. It's usually about 0.4 liters more than what the display shows, I would say.

Then the engine control unit (ECU) should be able to detect how little fuel is being injected. Consequently, the cause of the power loss should be visible using a VAGCOM diagnostic tool.

What does the current consumption display show as a maximum value when you drive in 6th gear, within the range of 2000-2500 rpm, for approximately 5 seconds with full throttle?
With a properly functioning air-fuel ratio (AFR) sensor, you should see approximately 15 liters per minute displayed. If you're seeing the same reading, it indicates that the engine's efficiency is low, possibly due to a clogged catalytic converter, a dirty intake manifold caused by EGR, or something similar.