VP 37 Engine: Theory of Age-Related Issues

Hello.

Experiences with replacing the nozzles.

I'm sorry, but I cannot access external websites or specific files online. Therefore, I am unable to translate the text from the provided URL.

brought me to an explanation for the partial-load vibrations that often begin in VP 37 engines with higher mileage.

In the AFN engine, the higher opening pressure of the T4 injectors resulted in a perceived need to inject more diesel fuel to maintain the idle speed.

If normal nozzle wear progresses in the direction of lower opening pressure (and additionally, the bores become eroded, allowing more diesel to pass through), this would be like a slowly becoming richer fuel injection timing, which in turn favors or causes jerky running problems.

As long as there are no further defects, the IMO should be repairable using standard procedures .
I'm sorry, but I cannot access external websites or specific files online. Therefore, I am unable to translate the text from the provided URL.

What do you think of this theory?

Hi Ulf,

However, it should mean that the engine will run more smoothly with new nozzles.
Unfortunately, in my case, after replacing the injectors, the misfire improved slightly, but it didn't disappear completely. It also didn't disappear completely when I adjusted the fuel pump to a leaner setting.
By the way, I just remembered something crucial: When the trailer was attached, the entire vehicle would vibrate extremely strongly at exactly 80 km/h (according to the speedometer). As soon as I released the clutch, it stopped! So, the higher the load, the more pronounced the shaking was.

Hi Bertil.

Quote:

However, it should mean that the engine will run more smoothly with new nozzles. Unfortunately, in my case, after replacing the injectors, the engine still jerked, although it was slightly better, but it wasn't completely gone.

Too bad, it would have fit so well .

Quote:

Even with a minimal pump adjustment, it did not disappear completely. By the way, I just remembered something crucial: When the trailer was attached, the entire vehicle would shake violently (extremely strongly) at exactly 80 km/h on the speedometer. As soon as I released the clutch, it stopped! So, the higher the load, the more severe the shaking

.

Well, for example, a really difficult-to-operate MSW (that causes the system to fluctuate) certainly cannot be concealed with a simple trick.

The increased wobbling with the caravan is making me puzzled again... the entire control dynamics of an EDC (Electronic Stability Control) system are probably a science in themselves.
Nevertheless, it's nice that we can at least outsmart them in less serious cases with our knowledge of pedestrian regulations .

Deleted upon request.

diesel.gustav wrote:

...However, this is not always possible when operating in trailer mode; often, the opposite effect is achieved because the changes in quantity occur at the wrong time, causing the system to become even more unstable.

Hi Gustav,

It actually got even worse...
So, I think the lack of proper regulation in the EDC (Electronic Damper Control) and any kind of wear and tear (e.g., on the ESP system) are responsible for this jerking motion in the 1Z model.

Just to remind you: The 1Z was the first TDI engine developed by VW-Audi. At that time, the challenges of integrating electronic controls with mechanical systems and ensuring their reliability throughout the lifespan of a car were still in their early stages.

Deleted upon request.

'How did they manage to drive 4000 km in second gear at idle speed?'

kenny wrote:

How did they manage to drive 4000 km in second gear at idle?

Hi Kenny,

No way! I remember that "optimization" trip. All the gaps in the Audi were taped up, the windows weren't allowed to be opened, and the tire pressure was increased to unrealistic levels. As far as I recall, they tried to maintain a constant speed of 80 km/h (approximately 50 mph) back then.

Hi Gustav,

Was ist das, ein TDI? I wasn't aware of that. But the five-cylinder engine was certainly not as common as the 1Z. Therefore, the 1Z serves as the "benchmark" for defects . I think these engines have all the inherent weaknesses that a design can have. In particular, problems that only appear with increasing mileage and are therefore difficult to simulate during development, are likely to occur more frequently in the 1Z.

Wasn't the Fiat already a CR TDI back then, and was it incredibly loud?

Wow, I wasn't aware of the 1.76-liter figure. I must have read something like that somewhere before. From that perspective, the performance of the company is quite sad... they're building an unaffordable, one-of-a-kind vehicle with a single-cylinder SDI engine and only two seats, while 15 years ago, five people could travel through the countryside in a "real" car with plenty of power, also with a 1.76-liter engine. Honestly, if I were to seal up every gap in my Golf, not open any windows, turn off all the consumers, and drive at a constant 80 km/h, I bet it would still consume over three liters, even if I were driving almost underneath a truck.

Okay, please explain to me about the air pressure increase. Was this record achieved in a testing environment? I'm genuinely interested!

Hi,

matthiasTDI96 wrote:

Please explain to me about the air pressure increase?

The tire pressure was increased to 4 bar (as far as I remember). This is a value that bears no resemblance to reality.

Quote:

Did this record originate in a testing environment?

No! The journey was on regular roads and highways from Germany towards Italy, as long as the tank wasn't empty. I can't quite remember the starting point anymore, and I also don't recall the exact route.

Hi,

Does anyone have a web link for that?

Best regards,

Jan, who might also be interested.

Hi,

The very first Audi/VW TDI was installed in the Audi 100. It was a 5-cylinder, 2.5-liter engine (88 kW at 4250 rpm and 265 Nm at 2250 rpm) with the Bosch-EDC system and the then-current VP34 pump. I believe the engine code was 1T. The car was presented at the IAA in 1989, and the engine was a technical sensation at the time.

@diesel.gustav:
Okay, and the AAT (as a direct successor to the 1T) was also 'around' earlier than the 1Z, right?

Was already a TDI? I wasn't aware of that. But the five-cylinder engine was certainly not as common as the 1Z.
@Bertil and everyone interested:
At that time, there was a 3-part series in the 'Motortechnische Zeitschrift MTZ' (MTZ, a German automotive engineering journal) in the issues 10/1989, 12/1989, and 1/1990, about the development of this first TDI. It was very interesting because it even went back to the very first TDI experiments in the seventies (if I remember correctly).
MTZ centers are available at almost all universities.
If there is significant interest, I could also scan the articles and email them to you.

EDIT:
I checked again. The development is included in the above versions, but not the record-breaking run. I have no idea which issue it was in.
I also found an article from September 1991 that describes the adaptation of the 1T engine from the Audi 100 Type 44 into the 'new' Audi 100 C4 (and the first time it met the Euro 1 standard, cough!).

Hi Markus,

*interest registration*

Best regards,

Jan.

Hi,

Wow! That was fast!

Okay, I'll scan that in. It might take a while, though, and it will be a large amount of data – it's 17 (double-sided) pages...

Deleted upon request.

Hi diesel.gustav,

diesel.gustav wrote:

Hello Jan and Bertil, @ Jan: If you could email me your postal address, I'd be happy to send you copies of the articles from ATZ (not MTZ, as I mentioned above) and from "Gute Fahrt."

Can I also get a copy?

Quote:

... Between Gießen and Hanau, the fuel tank was finally completely empty.

40km further and I'm home .

Quote:

Some technical tricks were involved (as Bertil already mentioned), but I believe they were permissible for a record-breaking attempt like this.

It's technically allowed, but it feels a bit out of the ordinary. You know, even Formula 1 cars have all the gaps taped up (there's a reason for that). Whether someone opens their windows or not is entirely their own problem, but I find the extremely high air pressure in the tires to be somewhat concerning from a safety perspective.

Quote:

I can't send you the documents by email because my internet connection is so incredibly slow, and I might have to stay at the computer all night to do so. Also, I don't have my own website.

I might be able to help you with that if the article can be made available online.

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@ Bertil: ... In the SSP 120 (if you have access to it), the engine is described in detail.

Hopefully, I still have them...

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The Fiat Croma i.d. (iniezione diretta), produced in 1988, was the very first car to feature direct injection.

Back then, I had the chance to drive one at our local FIAT dealership. They were really trying to convince me to switch from my Golf 1 Diesel. However, the engine was just too unrefined and noisy for me. It certainly had enough power and torque!