VW T4 TDI: Fuel Injector Timing/Lift Problem

"Hi, my new T4 is starting poorly. The timing belt was recently replaced by a specialist workshop. When logging into the diagnostic computer with the default diesel settings, the injection timing is outside the tolerance range, towards Top Dead Center (TDC). It's about 0.2mm before TDC at engine temperatures of 30-50 degrees Celsius. I didn't have time to warm it up. I've noticed that the injection timing is constantly fluctuating between 0.05 and 0.4mm. Is this bad? Does it always fluctuate this much? It also ran very poorly immediately after logging in."

Hi there.

Okay, my test program doesn't even run when everything is cold. The coolant should be at 90°C, but it's only at 30°C.

"My value is also fluctuating a bit."

"If you're only making dynamic adjustments, I'll initially set the belt so that it runs basically correctly. Not excessively noisy, and not producing excessive white smoke. Once it's roughly adjusted, I'll warm it up and take measurements. Unless I have to replace the pump itself, like last time, there's often not much else needed – the tensioner can compensate for a lot."
With the other pump, I had to open the camshaft and adjust it.

Hi,
How/with what did you measure the start of the acceleration? The value of 0.2 mm before TDC (Top Dead Center) seems unlikely to be from a dynamic measurement, as does the range of 0.05 to 0.4.
hg
Herbert.

Herbert wrote:

Hi, How/with what did you measure the start of the acceleration? The value of 0.2 mm before TDC (Top Dead Center) seems unlikely to be from a dynamic measurement, as does the range of 0.05 to 0.4. hg Herbert

"By the way, that information doesn't mean anything to me either. However, it seems there are several different display values. My program shows the injection angle in degrees, and the range is from +0.5 to -2.0. My VP37 engine with the 5-cylinder configuration runs best around -1°."

I'm also investigating a highly variable injection timing, possibly related to the crankshaft central bolt.
hg
Herbert.

The issue of a loose KW (eccentric shaft) bolt is more common in the 1Z engine. At most, the pulley adhesive might come loose in the 2.5 TDI engine, but that doesn't affect the valve timing. I used a program called "Gidis" at a friend's workshop; it's quite old. When the engine is running, it displays the injection point as a point on a graph, showing the injection timing (0-100, where 100 represents 1mm before top dead center) and fuel temperature.
I prefer to park the car myself. Do you also do that with the engine running?

Without wanting to promote anything: With VCDS and the TDI timing checker, you can see at a glance whether you are within the tolerance range.

Unfortunately, I cannot provide any information about the millimeter values due to the lack of comparison data.

You could check if your ESP is set too much towards "late," which you can tell, among other things, by the duty cycle of the injection timing adjustment.

Slight "fluttering" or instability at the start of the injection process is normal. Of course, the belts and tensioners on the AHY should be in good condition and have the correct tension.

Generally, regarding the functionality and assessment of the injection start setting on the VP37:
I am unable to access external websites or specific files online, including the URL you provided. Therefore, I cannot translate the text from the German link.

Best regards, Rainer.

Hi,
Gidis = Grundig Instruments' diagnostic and information system. Grundig Instruments was acquired by AVL DiTest.
As a hypothesis: Gidis displays the values 2 (EVP) and 9 (fuel temperature) from module #0.
This explains the measurement range of 0 to 100.
However, even then, the values for mm and 0.05 don't seem to fit.
Here are the target values for the AHY: http://www.dieselschrauber.de/Solldaten_5_Zylinder_VE.html
Unfortunately, the results of the EM (electrocardiogram) test for T are missing. You might want to have them printed out from your doctor's office or obtain a copy from the medical records department.
Of course, the measurement must also be taken here when the coolant temperature is above 85°C.
hg
Herbert.