Golf4 ARL: Low RPM Power Loss Troubleshooting

Hello,
I own a Golf 4 TDI GTI Exclusive, manufactured in 2003, with engine code ARL. I bought it in 2004 with 12,000 km (and it currently has 30,500 km).
"The problem, which has existed for a year now, is that when I accelerate below 1700 RPM, I don't experience much power until 2500 RPM (the driving behavior is like a gasoline engine or a naturally aspirated diesel). However, if I accelerate starting from 2000 RPM, this problem is not as pronounced."
He can still reach his top speed of 220 km/h, which is fine. Initially, it was 230 km/h, but now he weighs about 100-150 kg more, and I'm already quite satisfied with that.

I've already checked the usual suspects: I've replaced the mass airflow sensor, the charge air hoses have new seals, the VTG (variable turbo geometry) unit is moving freely and is at its limit at -0.6 bar, and I've replaced the diesel filter.

Since I only just received my semi-professional equipment today and couldn't use it before because I was missing a laptop, and my car isn't yet roadworthy, I could only check the basic values, such as the temperature sensor and pressure sensor. However, these were within the tolerance range, with a difference of 2° and 5 mBar (displayed as 980 mBar and 985 mBar).

I'm currently trying to figure out which types of vehicles I should prioritize logging together, and I'm planning to do this on the highway this Saturday.

Best regards,
Marco

Today I took some logs using VAGCOM, specifically channels 007-011 and 008-010, and to me, they look normal.

/viewtopic.php?p=107433#107433

Best regards,
Marco

Hi,

It looks normal to me. Starting around 1900, the maximum amount is released and maintained. It's not possible to see from the log why you claim to only notice proper acceleration after 2500.

Perhaps, for safety's sake, you could try running a 1/8 or 9 log to see if the injection amount is being limited by something else.

Regards,
Sure, here's the translation:

"Guste" is a German word that means "gust" or "gust of wind." It can also be used to describe a sudden burst of something, such as laughter or anger.

Hello,
When I got the car, it would fully accelerate from 1700 RPM, which was enough that I didn't have to deal with wheelspin in 3rd gear. However, a year ago, it sat for 3 months, and since then (9 months), the problem has been that it takes too long to reach full acceleration.

And the 001-008-009 Logg, highway, 5th gear, but I also think it's great as a loan.

I took some more logs today:
001-004-010
001-004
004-006
006-007-010
006-010
011-013-018
011-018-023
"All five gears, but since I don't know which ones are relevant, I will process them as needed."

Best regards,
Marco

Okay, I can't understand your problem with the poor low-end torque either. For example, in the 7-11 log, the torque curve is perfectly normally shaped: it's steepest around 2000 rpm, but it starts increasing well from 1500 rpm.

"Let's log a basic setting of the MWB 11; perhaps something is misaligned with the VTG end stop."

Hello,
KPower produced 110 kW and 400 Nm of torque in 5th gear while driving on a straight highway.
"From the 4th gear onwards, there's enough power available from 1700 RPM (although it feels like there could have been more, unfortunately, I don't have my father's 330d xDrive anymore to compare it to, as I used to drive that). However, in the 1st to 3rd gears, it revs up too slowly and comes out of the low RPM range too gradually, compared to how it used to perform before it was idle for a while."

And the LOG-01-011-xxx-xxx is in the default settings mode, unfortunately only available as a CSV file because I no longer have access to Excel; I won't have access again until next weekend. Also, it takes about a week to process new logs because I don't have a laptop and have to borrow one.

Best regards,
Marco

Marco115 wrote:

And the LOG-01-011-xxx-xxx in the default settings mode, unfortunately only available as a CSV

.
It is readable, though.

The drop in RPM when switching to "on" seems a bit weak (in my case, the RPM drops for a longer time and down to 42 RPM), and the pressure build-up as well.

-> I would check if the valve timing gear (VTG) is free to move, and if so, I would try loosening the small adjustment screw by about half a turn.

Don't ask me how such a problem could arise from a long operating time...

Hello,
"The VTG (variable torque generator) is working freely. This weekend, I'll try adjusting it using the set screw."

"In my previous Golf 4 Combi TDi with 115 horsepower, I also experienced this problem after just six months of inactivity. The engine had only 10,000 kilometers on it, even though it was a replacement engine (covered by warranty)."

Best regards,
Marco