Not LLM: Poor Performance Explained. (Solution)

Hello everyone,

I recently registered on this forum because I came across the post 'It's working again,' and it gave me some hope.

As a mechanical engineer, I'm not completely inept with technical matters, but I'm also quite inexperienced. So, here's my question, and I need to explain it in more detail:

Okay, so: We've been driving a PASSAT Variant, PD model with 115 horsepower for almost two years now. By the way, the engine code is AJM!
First registration: 06/99 (model year 2000). Absolute top speed: with a very long run-up, 195 km/h [shouldn't it be closer to 210 km/h if everything is working correctly?].
Since I drive approximately 100 kilometers of highway per day, the car is driven quite fast. Biodiesel is not used as fuel.

The car was purchased used by an employee of the company. The mileage at that time was approximately 22,000 kilometers.

Currently, it has approximately 75,000 kilometers on the odometer, and I'm still experiencing issues with its performance and acceleration.

It feels quite sluggish, and above 150-160 km/h, the power starts to drop off. In some cases, it can even be dangerous when you floor the accelerator... and there's not much response.
The LLM was replaced, and the AG check valve was replaced, but none of these actions resolved the problem.
Having been to several workshops and now being completely broke, I'm hoping you might have some information.

Then, as I mentioned before, I read the post titled 'Now it's working again.'

The turbocharger was supposedly checked.
I had already asked during the first visit to the workshop whether the problem could be related to the charger or the control valves, etc.

Unfortunately, I don't know which charger is installed, and I don't know how to distinguish the types as a non-expert.
I've heard of Garett, VTG, and KK%K a few times, but that's all I know about them.

Oh yes: I've noticed something occasionally: The fuel consumption is usually between 7 and 7.5 liters, but sometimes the car seems to perform better, and yet it uses less fuel, around 6-6.8 liters, even at the same speed. However, in those cases, the accelerator pedal feels heavier and is harder to modulate.
I'm not sure if it's related, but I was starting to think I was just imagining things, but recently, even my brother-in-law noticed that our car wasn't pulling properly when he was driving his 90 horsepower diesel Passat.
Perhaps you can help me.

I wonder if I might have the same pressure vessel, membranes, etc. Does anyone know if it's the same?

How can I test something like that?

Okay, that was a lot of questions, thank you very much for your patience.

Greetings to the forum from the new member.
Your increasingly desperate Thorsten .

Hi.

. . . to conduct a measurement run, read out and document important engine data (boost pressure, fuel injection quantity and timing, engine speed, air mass, throttle position), and then post the results here.

Our measurement data specialists will hopefully take a look at it and be able to provide tips on where the problem might be.

Hello.

A diagnostic test drive is probably the best way to troubleshoot problems, although minor issues can often be overlooked. (Especially if the workshop is doing it.)

I once had similar problems with my Golf. It also felt different when pressing the accelerator pedal. It turned out to be an issue with the electronics of the accelerator pedal. I can't tell you exactly what was replaced.
Perhaps it would be worth exploring that direction.

Greetings.
Jean.

Hello and thank you very much.
Thank you for the information.


I had already implemented the information from Ulf.
As he suggested, I was already at the workshop about a year ago.
I think I no longer have the printouts.
I once rode with a mechanic who analyzed everything while we were driving.
Without any findings, our Passat had been in the workshop more often than driven (a slight exaggeration ).
To be honest: I've given up... I'm desperate!

But still:
It's good to have your common sense validated by others.

I had also suggested Jean's idea, mainly because I sometimes feel like it's working a little better (but only for a short time).
But nowadays, I think it's more likely related to the turbocharger or something similar.

Yesterday, on the way home from work, the car was running relatively poorly.

Suddenly, the accelerator pedal became harder to press, and it felt like there was more resistance.

After that, I felt like the turbocharger had more power, provided better acceleration, and even seemed to offer better fuel efficiency.
Regarding the fuel consumption, that's probably more subjective; I was driving faster than usual because I was so happy that it was running again .

I guess it's some kind of silly mistake, and right now, the only things that come to mind are the vacuum pump or the boost pressure control valve!

Despite everything, thank you again for all the ideas .
Sure, here is the translation of the text from German to English:

'So long'

This phrase is a common way to say goodbye in English. It is similar to the German phrase 'Auf Wiedersehen'.

Here are some other ways to say goodbye in English:

* Goodbye
* Bye
* See you later
* See you soon
* Have a good day
* Have a good evening
* Have a good night

I hope this helps!
Thorsten.

Hi,

"If the accelerator pedal feels heavier than usual, there's definitely something wrong with it. TDI engines have electronic throttles, meaning the pedal is only connected to a potentiometer; there's nothing else connected to it. In particular, there is no mechanical feedback to any parts related to the ESP or turbocharger systems."

If the feeling of heaviness isn't just a subjective impression (because things weren't going well at that moment), then something is broken in the pedal mechanism.

Here's what could be done: Use a diagnostic tool like a tester or VAG-COM to read the throttle pedal position, and slowly depress the pedal - if there are any jumps or inconsistencies in the values, something is broken.


Or simply check if the pedal is mechanically okay, and if there's anything catching or jamming.

Best regards,

Jan.

So, some other simple things would probably be:

- Replacing diesel filter ( probably too simple).
- Check the spray pattern of the nozzles.
- Perhaps something was misadjusted during a possible timing belt replacement (like the injection timing, etc.), but I'm not very familiar with PD engines.
- Air filter okay?
- Is the distance by air short?
- iO Taktventil?

Hello,

In order to test the spray pattern of the nozzles, the PD elements must first be removed, which is a time-consuming and expensive process.

I would, as Ulf suggests, have another measurement taken and the values documented. Even if the workshop (or the mechanic) says that everything is correct, that doesn't necessarily mean it is (see many posts in the forum).

hello thorsten,
I've now driven my AJM for 50,000 km. The highest speed I've ever achieved, according to the speedometer, was 200 km/h (with a lot of acceleration, no wind, and an outside temperature of about 20°C). When I compare that to driving a Skoda Fabia with a 100 hp TDI (year 2001), I suspect that the AJM doesn't actually have much more power.
The consumption figures you provide also match my own.


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

'Hello,'
hans

Okay, a quick question: What's the stated value in the documents?

And: How is the gear ratio in the 5th (or 6th) gear? The Passat is heavier than the Golf or Ibiza, so it's quite possible that the gear ratio is too short to allow for significantly faster speeds. Beyond 4000 RPM, the power drops off quite sharply, and you're already operating in that range.

As a reference point, what is the engine speed in RPM when the speedometer reads 100 km/h in the highest gear?

For comparison: In my Ibiza with ASV (110 hp), the engine speed is just over 2000 rpm when fully revved. According to the speedometer, the top speed is around 205 km/h after a relatively short acceleration, sometimes even 210 km/h.

Best regards,

Jan.

Hello Hans,

Thank you for your contribution.
'The issue of performance is something that's been giving me a lot to think about.'

You often hear that some models can achieve speeds of 210-220 km/h (likely without any modifications).
Sometimes I suspect that the 115 hp output of the PD engine might have been 'detuned' or 'restricted,' which would explain why some examples perform significantly better.

I wouldn't be surprised if we have the same defective part (mine was manufactured on June 22, 1999!) - Model 2000!
As I said, it wouldn't surprise me.

I don't actually think it's normal to reach almost 200 km/h with a slight bump and tailwind, but what bothers me most is the fuel consumption: in my opinion, it's simply too high.
When I try to drive the car quickly, I do so on the highway.
'Sometimes it accelerates quite quickly in 5th gear (from around 2000 RPM), while other times it's very sluggish. Sometimes it pulls well and uses less fuel, even though I'm using the same tank of gas! Honestly, I find it all quite baffling. ...and the workshops apparently have absolutely no clue (at least, the many I've visited!).'

Regards,

Thorsten

Hello Jan,

I DON'T KNOW THE TRANSLATION.
You're right, it's probably a bit heavier, but I don't think that should make much of a difference with the torque.
Normally, I'm just happy to reach 4000 RPM.
IF the car wasn't so restricted, it would definitely be able to reach speeds of around 220 km/h. I'm actually convinced that if it can roll, then it can roll!
That's probably the point. I assume the loader isn't running as it should, which means less power and a lower top speed.
However, what I've noticed is:
Sometimes, it reaches 2000 RPM in 5th gear (5-speed transmission, Comfortline).
When accelerating to 170 or 180, then don't take the sausage off the plate .
I need to check what RPM the engine is running at when the car is traveling at 100 km/h in 5th gear.
I'd be happy to provide more information.

But Seat cars, at least those manufactured up to and including the year 1999, have a particularly aggressive torque curve.
It's probably due to the corporate structure. I think I have a copy of that somewhere. I believe it mentioned that they are supposed to compete against BMW! We still have an Ibiza from 1999 with a 60 horsepower gasoline engine, which is actually quite good, but it's starting to show its age.


Update: 07/04/02
'Der schnelle braune Fuchs springt über den faulen Hund.'
This morning, while I was driving to work, I checked the relationship between the engine speed and the vehicle's speed.
2000/U => 100 km/h
3000/U => 145 KM/h
I hope this is helpful. At a speed of approximately 195, the engine would be running at around 4000 RPM, but this speed is only achieved weakly.
Could the engine's maximum speed be increased to 4100 RPM without much effort?

So long .
Thorsten.


P.S. to Hans' email: How high does your engine's RPM reach at top speed?
Do you have a 6-speed transmission?

Thorsten,
At 100 km/h on the speedometer, it's exactly 2000 RPM.
At 200 km/h on the speedometer, the engine speed is just over 4000 RPM (4100, 4200?? I'm not sure, it should ideally be directly proportional, I need to test that again...). Beyond 4000 RPM, there's definitely 'turbo lag' on a flat road. The car has a 5-speed manual transmission. However, I always use about 2.2-2.3 bar of tire pressure in the front tires instead of the recommended 2.1 bar.
What annoys me the most (much more than 'just 200 km/h'): the engine doesn't really start pulling until around 1200 RPM. In the city, the engine just barely manages to 'get out of the basement' (when I shift from 1st to 2nd at 1800 RPM). In contrast, the 100 hp PD model also gets going nicely from around 1000 RPM.

Hi Hans,

Hello Hans,

Maintain the tire pressure at approximately 2.2 bar.

'The thing about using the speedometer to measure RPM also makes sense to me (see my previous response to Jan).'

My engine definitely doesn't start pulling until around 1500-1800 RPM, but I usually drive gently using higher gears.
I can't get 4200 RPM in our car. Even with a good day, a tailwind, and using high-octane fuel, and if I haven't eaten breakfast, I might be able to reach 4100 RPM, which translates to roughly 198-205 km/h! But I think I've only managed that once.

That number, 4000, also makes sense to me.
What model do you have? Ours is the Comfortline model.

Regards,
Thorsten

Hello fellow sufferers,

I'm experiencing the same problem as described above.
Diesel TDI PD, 115 hp, AJM engine, 5-speed manual, located in the upper section.
Speeds are very weak, meaning I can't [achieve something].
according to the climate control display (not the speedometer), 185 km/h.
straight line, no wind.

Das sind nach Tacho so ca 200 KmH. More is not.
It fits well in the torso and the fit is generally good in the lower part.
...except for the first few meters when it's completely cold.
Then he has absolutely no strength, not even enough to...
Approach!

The engine speed is exactly 2000 RPM at 100 km/h.
At 200 (indicated on the speedometer), approximately 4100 RPM.

But once it gets warm, it generally runs quite well.
He just doesn't have the strength anymore, especially in his upper body.
I know that a diesel engine doesn't have much power at higher RPMs.
'But I can't even reach 4200 RPM in 5th gear.'
The LMM is clean (visually). The wires are definitely okay.
blank.

Ihr habt Probleme mit der Abregelung. I've met him before.
Let it run at full speed with the machine still warm - then I noticed that...
It stopped in the 4th gear at almost 4,900 RPM.
No haggling!


Best regards, Holger.

Hello Holger,

The fact that the transmission is operating near its limit at 4000 RPM is a problem.
That's a different issue.

It seems the issue is related to the airflow, which varies significantly on different days. This is likely due to a different cause.

I don't believe that, under normal conditions and with full load, the transmission typically reaches 4200 RPM.
I think that was the case with the 110 hp TDI.
But maybe you're right about the throttling problem .
Perhaps someone knows more about it?
I think there might be something we could do with the charging rate range.
(Comparison to apples and oranges: A Jetta with a 70 horsepower diesel engine, after being modified with a turbocharger, could reach speeds of 190-195 km/h!)
Sure, here is the translation of the text from German to English:

'So long'

This phrase is a common way to say goodbye in English. It is similar to the German phrase 'Auf Wiedersehen'.

Here are some other ways to say goodbye in English:

* Goodbye
* Bye
* See you later
* See you soon
* Have a good day
* Have a good evening
* Have a good night

I hope this helps!
Thorsten.

Hello everyone,

It might sound silly, but have you ever considered that on warm days, with the air conditioning running, you might be losing around 10% of performance? This is especially noticeable as a lack of power at lower engine speeds, below 2000 RPM. (Of course, this isn't an explanation for actual performance problems, but it really does make a difference.)

Furthermore, as an immediate measure, I would also check the air filter and possibly replace the fuel filter.

By the way, I always keep the tire pressure in my Golf at 3 bar. The tires feel much more stable. However, the tire wear pattern is still perfectly even.
Greetings.
Jean.