VW T4 111kw AHY Idle Jerking/Hesitation

"Hi, my bus occasionally jerks when the engine is cold, and one cylinder seems to be misfiring. I removed the injectors and had a specialist check the opening pressure, and they were all within the range of 180-190 bar. I replaced the glow plugs with Beru plugs in May. The fuel consumption is around 7.6-8 liters per 100 km. I've now replaced the injector nozzle holder (with brand-name parts) as a precaution, and adjusted the injection timing to 0.56 using a Mega Macs 55 Harrgenau (it was fluctuating between 0.40 and 0.65). However, it still smokes occasionally, especially when cold, and jerks at idle and up to 1300 rpm. The vacuum pump is making noise frequently and will need to be replaced soon. The turbo is leaking a little oil, but it's not enough to be noticeable on the dipstick after 3000 km. Does anyone have any ideas?" The error memory shows no errors. "The parameters are all fine so far. Sometimes, there's a lack of power. Maybe the turbo adjustment is stuck?" The vacuum lines are in good condition.

Mileage? Idle speed control? Soot color?

Body with 264,000 km, engine with 185,000 km. White to blue smoke. Smells like diesel! How do I check the idle speed control?

I blocked the exhaust gas recirculation system, even though it was working. After that, the engine ran much smoother while driving. I usually add about 100ml of 2-stroke mixing oil to the diesel. Since then, it's been running more quietly.

Please set the start time for the spraying to the early limit.
With over 200,000 km, the 5-cylinder engines often don't perform as well as they should, even with ideal values.

The idle speed control function is located in measurement block 13 of the engine control unit. Naturally, 2-stroke oil doesn't really help with blue smoke...

I tested the injection start timing with values of 0.35, 0.55, and 0.75. I drove the car with each setting. It runs best with the current settings. I didn't use the data logging feature of my Mega Macs 55; I only recorded the parameter values. Can I test the needle lift adjuster?

sebv6 wrote:

Can I test the needle lift generator?

Resistance between the contacts: 80-120 Ohms.

TDI-GTI-4-Motion wrote:

Please set the start of the injection to the early limit. With over 200,000 km, the 5-cylinder engines usually don't perform as well anymore, and often don't reach the ideal value.

Correct

RedR32 wrote:

sebv6 wrote: Can I test the needle stroke generator? Resistance 80-120 Ohm between the contacts.

Just a reminder: If the resistance is too high or too low, the NHG is definitely defective.
Unfortunately, having the correct resistance value doesn't guarantee everything is okay, as interruptions can still occur during operation. Usually, the engine control unit (ECU) is best at detecting faults in the negative high-voltage (NHV) system (through the fault memory). Unfortunately, there are sometimes exceptions to this rule. I am aware of a few instances (specifically, two so far) where a faulty NHG (No-Harm Guarantee) was not detected by the engine control unit.

Best regards, Rainer.

Hi,
I'm familiar with a defect in the needle lift solenoid from the 1Z engine, which manifests as hard misfires under load, especially when the engine is hot. Nothing appeared in the error memory.
Does the error persist if you disconnect the needle lifter? In idle and under low load, the emergency mode should not mask the underlying issue.
The ESP readings (measured with your tool) can only be evaluated if the fuel temperature is known, the engine is above 85°C, and the tool is set to its default configuration.
If he doesn't do the latter, you might just be constantly pushing against the regulatory limit by adjusting things. If that's the late cutoff time, then you'll have a problem.
What exactly does the Mega-Max offer?
hg
Herbert.

Hey, the fuel temperature is displayed along with the injection timing, so it should be working correctly. I've also adjusted it earlier or later and done test drives. You can adjust it slightly by rotating the rear pump tensioner. Today, I checked how long the glow plugs are activated. It starts poorly below 3 degrees Celsius, stutters, and smokes if I don't preheat it twice. Turns out, it's only glowing for about 4 seconds. Now, for the data from "mega macs" with a cold engine (driven 30 meters to the workshop at -2 degrees Celsius): fuel temperature (7 degrees), air temperature (7 degrees), and engine temperature (13 degrees). I just replaced the temperature sensor as a general measure. Let's see how it starts tomorrow. By the way, last week, the new serpentine belt broke, and I replaced the tensioner and alternator."The tension and guide rollers have been replaced. The vacuum pump is also new because the old one was faulty. There are no deposits in the U-pump."