Reluctant PD motors: Serial error? ATTENTION: Do NOT change any HTML tags, BBCode tags, or URLs in the text!

Hello,

I often hear that PDs are not as responsive as VP-TDIs, especially above ~ 3500 rpm, there is hardly any power.

I now wonder where this judgment comes from.

OK, most PDs have a more pronounced torque peak than VPs (as a ratio between the torques at the maximum and at the rated power).

The biggest drop is with the 85 kW PDs with 310 Nm. 310 : 201 Nm means that the torque from 2000 to 4000 rpm decreases by a full 35%, so about twice as pronounced as the 81 kW VP with 235 : 193 Nm or 18% loss.

The ASZ with 310 : 229 Nm = about 26% loss could also be considered "stuck" at high speeds.
From the factory, I even noticed something: in the DZR test, my engine was clearly firmer above 3500 rpm.
But equally clearly, this property has disappeared since I corrected the NW setting to the correct value. Now it is no longer comparable to the AFN.
The error was about 3° KW in the late direction.

I can even imagine this as a mass production defect:
If the KW stop is set on the gear and then the engine is turned forward with a bit of "oomph" (because it should go fast), until the locking KW stop blocks the movement, then IMO, elastic or plastic material deformations could occur, so that the KW only comes to a standstill after the actual OT.

In addition, every tool needs some play so that it can be accepted and easily removed. With the small KW gear, this naturally results in a relatively large angular play.

Adding deformations and play, the total error IMO should quickly grow to the single-digit degree range.

If the NW wheel is then set as if the KW wheel is at OT, the error is complete - and the engine appears more or less unwilling to turn (the same can of course also happen when changing the ZR in the authorized workshop).
On average, all PDs would result in a too late NW setting, which could explain the often expressed impression that PDs are sluggish at high speeds.

Even badly adjusted engines seem to be able to cope - like the Fabia RS, which the test bench certified to have a torque drop from the factory at high speeds compared to the other cars, with the result of just over 120 hp instead of the 130.
(I downloaded this test as a pdf from the Hopa website in January. But Hopa is apparently currently offline, and the pdf is probably too large (over 3 MB) to attach as an attachment . . .)

So, that's mostly speculation. The only thing I know for sure is the setting of my engine before and after.
What do the rest of this round say about my theory?

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I can also imagine that this will help reduce the power of the Pd. motors in the upper speed range, so that the VTG can still control the turbo precisely and not overshoot. As it is currently with my tuned VP-Tdi.

The reason for this is that the exhaust flow is increased in the upper speed range, so that the VTG runs at full capacity and the boost pressure still increases.
Now, a larger turbo, such as a VNT 20, would help.
This would have the disadvantage that it would only start to work fully at around 2000 rpm.
This is my theory and information.

I hope it has come across as I intended!

Conclusion:
The manufacturers leave a large safety margin for these unwanted turbo regulations.

Can anyone else agree with this?

@ulf

So, I can't understand why the 85 kw PD (AJT) should drop by 35%. I even think it's more aggressive than our beloved 1Z. The ATJ willingly revs up to 4,500 rpm (in 4th gear), then drops, which the 1Z didn't do, although it could also rev up to over 4,000 (unfortunately not in the last gear, but the ATJ can't either). I actually don't notice any difference from the old VP (except for fuel consumption, which the new Passat unfortunately needs more of).

Our ATJ has already had a timing belt replacement.

Regards, WarLord

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So, I can't understand why the 85 kw PD (AJT) should drop by 35 %. I even think that it is more "stubborn" than our beloved 1Z. The ATJ willingly revs up to 4,500 rpm (in 4th gear), then drops, which the 1Z did not . . .
Hi,
then one could assume that the NW setting on your AJT is correct.
If you look at the torque tables in the driving simulator (and the "Nm levels" between the speeds in the 200 rpm grid), you will notice that the PDs drop approximately linearly between 2000 and 4000. In particular, there is no "steep drop" in torque between 3000 and 4000, which would have to be the case according to common complaints.
The 110 PS VP, in particular, holds the Nm constant at over 2000, then drops relatively more at around 3000 rpm.
Due to this data, in practice, the 110 VP should show the characteristic that is so often attributed to the PDs.
These considerations and your experience with the AJT (does it also have 310 Nm?) and, not least, my engine confirm my suspicion that the "nothing comes after 3500" wisdom could be based on (massively) incorrectly set PD NW.

Steffarn wrote:

I can also imagine that this would allow the Pd. engines to be optimized in the upper speed range, so that the Vtg can precisely control the turbine and not overshoot.

Hi,

this would only be a problem if it were structurally impossible to further expand the Vtg's operating range to "torque" (i.e., past the drive turbine) even at full load.
(Because this would also solve your problem.)

But I can't quite imagine that it shouldn't be possible . . .

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then one could assume that the NW setting is correct in your AJT.

If you look at the torque tables in the driving simulator (and the 'Nm levels' between the speeds in the 200 rpm grid), you will notice that the PDs decrease approximately linearly between 2000 and 4000. In particular, there is no 'steep drop' in torque between 3000 and 4000, which would have to be the case according to common complaints.
On the other hand, the 110 hp VP holds the Nm almost constant at first, above 2000 rpm, before breaking more strongly above 3000 rpm.

Due to this data, in practice, the 110 hp VPs should show the characteristic that is so often attributed to the PDs.

These considerations and your experience with the AJT (does it also have 310 Nm?) and, not least, my engine confirm my suspicion that the 'nothing happens above 3500' wisdom could be based on (massively) incorrectly set PD NWs.

This is not an AJT, but an ATJ. Is the 85 kw PD engine with 310 nm, which was built for the 6 speed gearbox.
I assume that it must be the setting of the camshaft. A timing belt change has already been done on the car (it was bought afterwards) and I was really surprised that it could run so far. We have a few new Tourans at work (good, but already have 25,000 km), which are just being run in and after 4,000 rpm, nothing happens, but it goes normally up to 4,000 (subjectively). But I noticed something with the ATJ: you can somehow notice that the torque is regulated in steps up to 3,000 rpm (but I'm blaming the leaky air-to-water cooler for that). Let's see how it goes with the new air-to-water cooler.

Best regards, WarLord

My AJM (85kw) definitely runs better after the timing belt replacement.

I also have a large turbo and the other PD components, but I'm not sure if I want to try it because I'm going to school in the next 2 years and I can't afford to damage the engine...

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DaBibo wrote:

My AJM (85kw) definitely runs better after the timing belt change.

Hmm, that could also be due to an extension of the timing belt, which naturally also delays the NW setting (although how much this can make a difference -> ????)

Or, your NW was also originally set too late, and the timing belt change was the first time it was correctly set.

Did you do the change yourself?
If not, then just the (presumably) correct timing belt setting would be a valuable tip for your workshop :twisted:

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DaBibo wrote:

My AJM (85kw) definitely runs better after the timing belt change.

Hi,
if Ulf's theory is correct, one should be able to observe this effect on a larger scale, assuming proper workmanship.

christians wrote:

if Ulf's theory is correct, one should be able to observe this effect on a large scale, provided that the work is done correctly

And that's exactly where (-> bold part of the quote) the problem lies - as long as "normal" workshops carry out the work.

Or, as many PD drivers check their NW settings themselves.
It's actually not that difficult - and you might get arguments that you can occasionally bring up in a discussion with VAG or a workshop :twisted:

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we hunted the ASZ a bit today...

it runs smoothly up to the red zone without seeming strained...

CU Gremlin

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@ Ulf,

I already wrote about it in one of your Gremlins topics. I decided to follow your instructions today when adjusting my ASZ (1. timing belt, 40tkm) and, lo and behold, the deviation was so small that I almost didn't want to loosen the NW wheel. I think it's just a little less than a degree, maybe a maximum of 2°. If I'm right, I'm either the third or fourth person to have done this (and found the time). It's really very doable, and Ulf's instructions get straight to the point. I used a blue Loctite sealant on the NW wheel side and also on the opposite side. I would recommend this to everyone, as it made the LC4 engines 100% airtight even in the early days of KTM.

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I have a Fabia TDI ATD with 101 hp and 240 Nm. Last year, the car still ran without major problems up to 4300 rpm in 5th gear, i.e. 220 km/h according to the speedometer. However, I don't want to start a debate about the maximum speed, but rather about the engine's willingness to rev.

Yesterday, my ATD only reached 4000 rpm slowly, even though nothing had been changed on the car (same tire width, ...), I even got a new air mass meter at 100% warranty in winter. Could it possibly be related to this adjustment, or is it simply an old air filter (I have 56000 km on the tachometer and the old air filter inside).

How can I, as a 'talented borrower', check this 'NW wheel' (please explain what it is) without electronic aids? Is this even possible. I have a technical education (mechanical engineering), so I'm not completely incompetent in this regard, but I'm still a beginner in the field of engines.

Best regards,
Jack )

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Hi Ulf!

One must consider:

A PD provides a right 'torque peak', a VEP not so much. My ALH completely lost its power above 3800 rpm (no wonder, 66kw were at 3750 rpm), after tuning it was a little better. However, it pulled cleanly from 1200 rpm onwards, before that it was dead below 1600 rpm.

The AWX spins freely up to the red zone, regardless of whether it's new or slightly worn. Subjectively, one feels that after this brutal torque maximum at around 1900 rpm, not much more comes. However, if you compare with other vehicles on the highway, you can already see that it accelerates quite quickly. 320d drivers are always complaining behind me, although this engine has a very smooth power delivery.

The most powerful TDI I have driven so far was the 1.4 PD_TDI in the A2... sound/consumption/performance-wise, a big thumbs up! ;)

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we hunted the ASZ today...


Also again.

Regards, WarLord

Jackrabbit82 wrote:

Yesterday, my ATD was running sluggishly at only 4000 rpm, even though nothing had been changed on the car (same air filter width, ...), I even got a new LMM with 100% warranty in winter. Could it possibly be related to this adjustment, or is it simply an old air filter (I have 56000 km on the tachometer and the old air filter is inside)?

Hi,
Just check the air filter
There are many possible causes for performance loss.
Starting with the LMM (even if they are sold as new, they can be defective), through clogged fuel filters, and boost pressure problems, etc.
5 km/h headwind - or tailwind, most people won't notice, but in the Vmax, it makes a difference of almost 10 km/h!

Quote:

How can I, as a "talented borrower", check this "NW wheel" (please explain what it is) without electronic aids?

Camshaft wheel.
Click here. If you don't understand it after careful reading, please be careful (don't take it personally , just for your own safety).

@Julian:

Quote:

A PD has a right "torque drop", a VEP not so much.

Yes. However, the drop is still almost uniform at higher speeds (in Nm loss per 100 rpm).
But if, according to reports, the power drops "abruptly" around ~3500 rpm, then the Nm loss per 100 rpm should be much greater from then on.

But at least with the powerful PDs, there is no such "dip" to be felt. Therefore, I consider torque drops significantly below 4000 rpm to be a defect or incorrect setting.

Quote:

The most eager TDI I have driven was the 1.4 PD_TDI in the A2...

I once drove a Polo of the latest generation with the 1.4 (75 hp) with 3 people. It barely got anything below ~1700 rpm.

And because of the larger ignition distance, 4000 rpm sounds like 3000 rpm in "normal" engines -> shift to the end, even though your ear tells you to "rev it further".
So, I don't really believe that.

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