Issue with starting the spray gun, model VP37

Hi,

I tried adjusting the fuel injection start using VAG-Com on my Golf III AFN today, following Ulf's instructions.

The basic functions are all working, meaning that if you select 'Basic Settings' and then 'Display Group 000' in VAG-Com, the engine speed slightly decreases → fuel injector controlled.
Field 9 also displays a plausible value for fuel temperature.

The problem is that the value in field 2 is constantly 000. According to the description, this field should display a value for the fuel injection start.

Perhaps someone here has experienced this problem before.

Best regards,
Andy

Hi Andy

I don't see much value in this adjustment method, because it only ensures the latest starting time in idle - which has almost no practical significance in real-world driving.

Instead, I warm up the engine and, in normal mode (i.e., not the default setting!), perform a full-throttle acceleration in 3rd gear. Speed range of approximately 1500 to 4000 rpm.
Here, the maximum sprue opening ratio should not significantly deviate from the performance-related optimal range of approximately 92 to 95%.
If so, the pump will be adjusted accordingly until the specified duty cycle is achieved under full load, and that's it.

Hello Andy,

"It's possible that your current injection start is so far off that the control unit is outputting the minimum value of 0. Why don't you compare the target and actual injection start values (read out from the measuring block) while driving, then you'll see what's going on."
When the engine is warm, the fuel injection starts relatively late at idle.
In the default setting mode, the fuel injector control is constantly activated and set to the maximum late-shut-off position. If this point is correct, then there is definitely enough reserve for early adjustment in operation.

Hello, Rainer

Hello Andy,

there was something for your car, Quote:

"The starting point of the fuel pump cannot be adjusted after a pump replacement."
Start value for adjustment in the default setting: "255" or "0"
Partial starting issues, especially in cold conditions

Cause:
Setting the "0" or "255" value for "Base Setting" at the beginning of the fuel supply can cause the fuel pump to inject fuel at a significantly later time.

Solution:
Adjusting the fuel injection pump setting in the basic adjustment.

Loosen the fuel lines and rotate the fuel pump approximately 4 mm further in the long slots, in the direction opposite to the engine rotation, away from the center of the long slot.

"Re-tighten the fuel lines and perform a new basic adjustment."

Hi, tinkerers,
After I had written the post, I also had the thought that the starting point for the spray might be outside the display area. I then turned the pump a good distance and immediately had reasonable values in display field 2. Setting it up was then easy. And now, he's starting up again, perfectly.
I will then re-examine Ulf's proposal for a final check.

Sometimes, you just miss something...

Best regards, Andy