Was ist da denn kaputt? 10 cent ohne Wirkung | Posts 16+

Um, thinking error!

The EDC always adjusts to its setpoint. So, even WITH a resistor set to 5mg/hub, it will adjust accordingly. However, due to the calibration issue, the actual amount delivered is more than what is indicated.

Therefore: When the engine is not running, check the voltage values of the fuel quantity control unit. On my ALH, it's somewhere around 0.6xx V, and this value decreases when the resistor is activated. This is because the EDC (Engine Control Unit) doesn't activate the fuel quantity control unit when the engine is not running, as there's nothing to control.

So, you can see whether the resistance actually has any effect.

however, you should also notice it even when idling. I can't add the 10 cents if the engine is running at idle. It sputters like an old lawnmower .

CU Gremlin.

Hi Gremlin,

Gremlin wrote:

um, thinking error! The EDC always adjusts to its setpoint.

Therefore, even WITH a resistor set to 5mg/hub, it will adjust to that value.

Quote:

However, due to the calibration error, the actual amount delivered will be more than that.

No. The EDC's quantity control system always adjusts to the target injection quantity, except when the engine is idling.
Here, the primary setting is to maintain '900 rpm'. If the target value were adjusted here, the idle speed would increase when the resistor is activated. However, this is not the case (as long as you don't exceed the limits). Apart from that, you would no longer have an idle speed control system, because the idle injection amount cannot be constant (keywords: engine oil temperature and viscosity, air conditioning, rear window heater, different fuel qualities, faulty glow plugs...).
Even if, instead of using idle speed for the test I suggested, we were to use, for example, 3500 rpm, the resistance would still be noticeable at a lower actual injection quantity.

Quote:

therefore: when the engine is not running, check the voltage values of the fuel quantity control. In my ALH, it's somewhere around 0.6xx V, and this value decreases when the resistor is activated. This is because the EDC (Engine Control Unit) does not activate the fuel quantity control when the engine is not running, as there is nothing to activate. So, you can see whether the resistance actually has any effect. "Of course, this is also possible. Within a measurement block between 10 and 20 – I've forgotten the exact value – the voltage values of the quantity setting device can be accessed during the EDC start-up test." Then you also have the maximum value.

However, you should also notice it even when the engine is idling. I can't add the 10 cents if the engine is running at idle. It sputters like an old lawnmower .
then your resistance is quite small.

Best regards, Rainer.

Hello everyone,

I have just finished taking the measurements.

Okay, Rainer, you were right: it's the ohm. The resistance between pin 1 and 2 is the same as the resistance between pin 2 and 3, which is 6.3 ohms in my case -> no potentiometer.

Fuel injection amount measured with VAG-Com:
It oscillates between 5.2 and 5.6, with no significant resistance.
with resistance, exactly the same, no change noticeable

What does that mean in my specific case? But what about the quantity switch?

Best regards.
David.

DocSnydor wrote:

Fuel injection amount measured with VAG-Com: It oscillates between 5.2 and 5.6, with no significant resistance. with resistance, exactly the same, no change noticeable What does that mean in my specific case? But what about the quantity switch?

Hi.

I can only explain it by saying that the resistor isn't "working" (in the right place).

So, it's either a resistor with too high a value (e.g., 10 kΩ instead of 1 kΩ), it's broken, or you've connected the wrong cables.

ulf wrote:

... I can only explain it by saying that the resistor isn't "working" (in the right place). So, it's either a value that's too high (e.g., 10 kOhm instead of 1 kOhm), it's broken, or you've connected the wrong cables.

Hi Ulf,

As you probably know, I'm very familiar with the fact that the pump (or rather, the flow meter) was defective in my 1Z. The Authal box was the only tuning box that worked. The Authal Box does not place the resistor between pins 2 and 3, but rather in series with pin 1.
The 10-cent tuning between pins 2 and 3 didn't have any effect for me either. I tried it with a 2K potentiometer and turned it down almost to zero --- with no effect whatsoever.

What DocSnydor (a faulty quantity setting device) says could very well be true!!

Bertil wrote:

As you probably know, I'm very familiar with the fact that the pump (or rather, the flow meter) was defective in my 1Z. The Authal box was the only tuning box that worked. The Authal Box does not place the resistor between pins 2 and 3, but rather in series with pin 1. The 10-cent tuning between pins 2 and 3 didn't have any effect for me either. I tried it with a 2K potentiometer and turned it down almost to zero --- with no effect whatsoever. What DocSnydor (a defective quantity setting device) says could very well be true!!

Hi Bertil,

What you've written was completely unknown to me until now, but your conclusion seems obvious...

I'm just wondering: if a pump is already so "broken" that it doesn't even react to a significant 10c tuning adjustment, why does the car still run with acceptable performance?

And what's even more puzzling is why a "faulty" pump no longer responds to the 2-3-tuning, but still reacts to the Authal intervention on cable 1.
Because, as far as I know, in the RWG evaluation stage, the ratio of the reference and measurement coils is converted into a DC voltage (which can also be read out using VAGCOM).
Why should this evaluation stage suddenly react in a "selective" manner:

ulf wrote:

What you've written was completely unknown to me until now, but your conclusion seems obvious...

Hi Ulf,

I never wrote about it before because I thought I was too stupid . However, I'm sure that I didn't connect the 10-cent tuning correctly. The car made a noticeable noise, but there was no power - the acceleration time was exactly the same, no matter where the potentiometer was set. With the Authal Box, it took about 1 second less.

Quote:

I'm just wondering: if a pump is already so "broken" that it doesn't even react to a significant 10c tuning adjustment, why does the car still run with acceptable performance?

... I have no idea either, but I wanted to bring this up because DocSnydor has the same problem and is also complaining about the jerky pumping (the workshop diagnosis was a faulty fuel quantity sensor, just like mine).

Quote:

And what's even more puzzling is why a "faulty" pump no longer responds to the 2-3-tuning, but still reacts to the Authal intervention on cable 1. Because, as far as I know, in the RWG evaluation stage, the ratio of the reference and measurement coils is converted into a DC voltage (which can also be read out using VAGCOM). Why should this evaluation stage suddenly react in a "selective" manner:

... to do that, I would need to think more about the function of the pump and its control. But at the time, I also didn't come up with any other ideas. By the way, I once tried a different box that worked fine in zone 1, but not with my setup (it was probably a box with pin 2 and 3 connected).

Bertil wrote:

... to do that, I would need to think more about the function of the pump and its control

.

Hi Bertil,

if you, as an advanced PD driver, are not too ashamed to waste your brainpower on outdated VPs .
- I'm curious to see the result.

Especially since, as far as I know, I don't have the opportunity to research such cases on a "living subject."

Perhaps our Rudi could also contribute something to the discussion - I haven't heard from him in quite a while .

ulf wrote:

... if you, as an advanced PD driver, are not too ashamed to waste your brainpower on outdated VPs . - I'm curious to see the result.

... sorry Ulf, the PD patent was filed in 1905 by a certain Rudolf Diesel, so it's likely the older concept. It was probably only mechanically impossible to realize for many years.

Quote:

Especially since, as far as I know, I don't have the opportunity to research such cases on a "living subject."

"... yes, you're not alone in that..." But I'll think about it for a few days.

Quote:

Perhaps our Rudi could also contribute something to the discussion - I haven't heard from him in quite a while

.
I emailed Rudi last week.

Hi Ulf and Bertil and everyone else...

I think it's great that you are all discussing the problem so actively.

Regarding my tuning: When I installed it back then, I let the engine idle and then I turned the 1k potentiometer (I'm sure of it) as far as it would go until the engine started to run unevenly (and sputter), and then I turned it back a little bit. I also have to mention that I installed the two antiparallel diodes, so the resistance is already set very high.
Then we took it for a test drive and were totally disappointed because there was absolutely no more power .

I've gotten used to the jerking and the poor acceleration. I'm now faster than a Corsa 1.2i! On the highway, it reaches a good 180 km/h. Hey...
If I ever have some extra money, I'll get the pump replaced before it shakes the whole car apart.

Best regards.
David.

DocSnydor wrote:

I think it's great that you are all discussing the problem so actively.

Hi David,

it's not entirely selfless .
Given the potential problems that TDI engines can sometimes produce, preparation is necessary so that you don't end up, eventually (along with many workshops ), standing like a bull in front of a mountain .

Quote:

Regarding my tuning: When I installed it back then, I let the engine idle and then I turned the 1k (definitely) potentiometer as far as it would go until the engine started to run unevenly (and sputter), and then I turned it back a little bit. I also have to mention that I installed the two antiparallel diodes, so the resistance is already set very high. Then we took it for a test drive and were totally disappointed because it had absolutely no more power

.

So, was was actually a reaction from the car... but then why wasn't there any extra power?
Question for pump specialists: Was there perhaps a generation of pumps (in the 1Z model) that was already running very close to its maximum capacity under normal full load conditions, to the point where it had no more reserves for a significant increase in performance?

Quote:

I've gotten used to the stuttering and the poor performance.

Hm... I remember advising Bertil back then to open the pump cover and check the valve stem for side play. It was difficult to check the functionality, but then the non-performer got in the way.

Perhaps it could be an option for you to continue using the old pump. Have large quantities of biodiesel ever been processed through the system during its operational history?

ulf wrote:

Hmm... I had advised Bertil back then to open the pump cover and check the switchgear shaft for excessive play or stiffness, but then the "troublemaker" got in the way.

... oh, I forgot about that. Of course, I had removed the pump cover a few days earlier. The points mechanism moved smoothly and could be moved with increasing force until it reached its limit. Without any jerking or stuttering.

Perhaps it could be an option for you to continue using the old pump. Have large quantities of biodiesel ever flowed through it during its operational lifetime?

I've never used biodiesel in it, because even for a 1994 model, it's not approved by VW.
I didn't open the pump myself, I'm not really comfortable working on it. That's why I went to Bosch, and they diagnosed a faulty mass airflow sensor. Due to being in shock, I unfortunately didn't ask what exactly was broken .
Well, replacing just the MST costs €600, while replacing the entire pump costs €750, so they advised me to have the whole pump replaced.
But, as you already mentioned, what surprises me: If the pump is really so broken that a new one is needed, then why can I still drive it so well, given the circumstances ?

Oh yeah, something just occurred to me:
He (the Bosch employee) had suggested that the jerking was happening because I was always driving in the same RPM range, which would cause the throttle mechanism to wear out in that specific range. Looking back, his explanation seems a bit 'vague' or 'unconvincing.' What do you think?

DocSnydor wrote:

He (the Bosch employee) had suggested that the jerking was happening because I was always driving in the same RPM range, which would cause the throttle mechanism to wear out in that specific range. Looking back, his explanation seems a bit "vague" or "unconvincing." What do you think?

Hi David,

The position of the pump does not determine the speed, but rather the amount of fuel injected.
"That is, whenever possible, for example, in the 5th..." When driving at 2000 rpm, the pump may have to deliver its maximum capacity on inclines, and downhill, the thrust cutoff engages – meaning that everything from zero to full load is possible within that range.

If, on the other hand, only long distances are driven on flat terrain (without wind ), the 2000 rpm is practically always associated with the same amount of fuel injection.
But even then, I cannot imagine "concentrated" wear and tear due to the structure of the aggregate system .

My suspicion is: typical, nonsensical rambling, just to say something...

Hi Ulf,

That certainly sounds logical. In our area, the terrain is sometimes hilly, so full-throttle rides are definitely possible, and it seems like that's when the jolting occurs. Now, the issue of stiffness also sounds very plausible. Very rarely, I've noticed that the engine didn't stutter or jerk, even when at a high RPM and under full throttle.

I think there was a thread in this forum about the procedure for opening the pump cover, including checking for any difficulty in operation (didn't it even originate from you?).
If that were to happen to me, there's not much I can do, is there?

David.

P.S.: Just a thought: The boost pressure builds up about 500 RPM too late. That's probably a different story, I just mentioned it to be sure.

DocSnydor wrote:

I think there was a thread in this forum about the procedure for opening the pump cover, including checking for any difficulty in operation (didn't it even originate from you?). If that were to happen to me, there's not much I can do, is there?

Hi David,

The instructions on how to open the lid and check the signaling system came from me. However, the original post might have been from someone else (Bertil?).
It's probably been about half a year, if you want to take a look.

If you dare to open the pump, you might even be able to eliminate any stiffness caused by deposits by manually rotating the pump shaft several times within the jammed area, while moving the shaft up and down (it has some play).

Quote:

P.S.: Something else that occurred to me: My turbocharger boost builds up approximately 500 RPM too late. That's probably a different story, I just mentioned it to be sure..

"Pump jerkiness and turbo boost pressure shouldn't really be related, in my opinion." But on the other hand, TDIs are always good for surprises .