Engine RPM Limited to 3000, Excessive Smoke

Hello,

'I'm having the following problem: I installed an injection pump from an AFN engine into a 1Z engine. I bought the pump from eBay, and it already had the defect mentioned. However, I completely disassembled the metering unit, cleaned it thoroughly (following the instructions), and checked the high-pressure section and the lift disc for signs of wear. I also checked the piston for the injection timing adjustment for smooth movement, and then, of course, reassembled everything carefully.'
After that, I adjusted the injection start timing using VAG-COM. The injection amount is approximately 5 mg/hour at idle.
The engine starts well, whether it's cold or warm, and it has good power, but only up to 3000 RPM. After that, it seems to be restricted, and it produces a lot of white-blue smoke.
New fuel injectors, including NHG (noise, heat, and vibration) components, have been installed.
'Error code 00550 (fuel injection timing) was found in the error memory, but it has not reappeared after being cleared.'
I personally suspect a fault in the injection start-up control system. That's why I checked the solenoid valve at the bottom of the pump, using the actuator diagnostics, and also while it was disconnected. It's closed when there's no voltage applied, and it can be blown through when voltage is applied.
I'm at a loss, what could be the reason?

Hello!

dieselcruiser wrote:

I'm at a loss, what could it be due to?

The hollow screw connected to the fuel return line acts as a throttle. This creates a pressure that is dependent on the speed of the pump.
Is the correct fuel injector nozzle installed? The injector nozzle is moved depending on the internal pump pressure, and the solenoid valve only performs the "fine adjustment."

Similarly, the impeller pump may be damaged. In this case, the internal pressure cannot be built up sufficiently -> pressure measurement.

All other "typical" errors should, of course, have already been checked (e.g., a sticking fuel injector, a worn valve lifter, stuck springs, etc.).

BYE
TDI mechanics.

I didn't know about the valve in the return line, thank you. How can I tell if it's the correct one?
The EB start is not being adjusted early enough, so the pressure for adjustment may not be high enough. Therefore, the throttle should be oversized (i.e., provide less throttling) in the flow path, or?
I still have another pump here; I'll compare the throttling settings.

dieselcruiser wrote:

The EB start is not shifted far enough towards the early stage, so the pressure for shifting should not be high enough, therefore the throttle in the passage should be oversized (i.e., not throttle down enough), or?

It could be like that.

For verification, simply perform a full-throttle acceleration in 3rd or 4th gear from approximately 1500 to 4500 rpm (or as high as it revs), and log the "Engine Speed" (Motordrehzahl) using VAGCOM, specifically measuring block 4.
Rule errors manifest as a difference between the values in columns 2 and 3 -> this can be easily studied in the log.

Habe mal MWB 4 und 10 geloggt. Die Drehzahl steigt schnell bis ca 3000 U/min, danach steigt sie jetzt weiter, allerdings sehr träge. Zwischen Spalte 2 und 3 ist doch eine deutliche Abweichung zu erkennen. Also stimmt der Einspritzbeginn bei höherer Drehzahl wohl tatsächlich nicht. Unwhy?
I once logged data for MWB 10, and now there's suddenly also an error related to the intake manifold pressure, but it might be caused by the constantly clicking magnetic valve for the turbocharger pressure.

The problem with the boost pressure has been resolved. After seeing 1250 mbar displayed on the diagnostic tool (MWB10) with the engine idling, I replaced the boost pressure sensor in the control unit. Afterward, the diagnostic tool showed a pressure close to atmospheric pressure with the engine idling.

I've found a possible cause for the malfunctioning spray nozzle adjustment: there are visible wear marks inside the pump housing from the adjustment ring. While the ring can be moved easily by hand within the housing, it's also missing any additional load, such as that from the lifting disc. Does anyone have any constructive thoughts on this?

Answer from Kilian
Okay, bitte gib mir den deutschen Text, den du übersetzt haben möchtest.

Hello.


The marks left by the roller bearings inside the aluminum housing are perfectly normal for a pump with moderate operating hours. The pump would still function properly even with significantly more pronounced marks.

Based on the log data, I can see that the injection valve remains in the late injection position even under full load. What's strange is that the duty cycle of the injection valve (cold start valve) is 96.5%. To eliminate this control deviation, the duty cycle needs to be reduced. (Emergency mode?)

The significantly low pressure inside the pump chamber could indicate a jammed rotor in the vane pump. Another possibility lies in the pressure control valve next to the pump inlet. Perhaps the pre-tension spring piston has come loose. I don't believe the throttle in the pump's return line could be too large; the differences between the 1Z and AFN engines aren't that significant. If that were the case, the injection timing adjuster piston would at least move slightly away from its late injection position.

The speed limit at 3000 RPM might be caused by the high-pressure plunger not receiving enough fuel when the pump pressure is too low.

Thank you for the response. In the meantime, I was able to solve the problem. By 'grooves,' I didn't mean the ones from the four roller bolts, but rather the two bare, wide strips (visible in the image above) that were caused directly by the adjustment ring of the roller bolts. These grooves were partially almost 1 mm deep. My second pump showed a similar wear pattern, but not as severe. This pump is from a 1Z model, but unfortunately, it's not entirely complete. So, I painstakingly removed the grooves in the pump housing of the 1Z pump using 1200-grit sandpaper by hand, as best as I could, and I transplanted all the components of the AFN pump into the 1Z pump housing (both have a 10 mm pump plunger, but different lift plates). Now the engine runs as it should, but I'll have to see if it lasts. By the way, I know from the previous owner of the AFN pump that he operated it with biodiesel, and it's also not unlikely for the 1Z pump, since the seals were leaking. So, could the biodiesel be responsible for the wear pattern? In any case, I don't use biodiesel!

Can you describe the differences between the different types of hub discs?
Or even provide images?

To the best of my knowledge, that's the only difference between the pumps, and I'm very interested in it.

Thank you.
m;

I couldn't tell the difference based on the shape of the impeller; they looked almost identical, but the numbers were different. I can easily take a picture of the 1Z impeller, but the AFN impeller is now back in the pump and working properly.

.. okay, then you just had to rotate the camera, and then you could take the picture.

Too bad, because I was wondering if the "ridges" on the disc appeared steeper or something like that...

Because in the engine noise, you can already hear a noticeable difference between the 1Z and AFN engines, and the only things that come to mind to explain that would be the pistons (with a different Omega groove) and different spray patterns (except for the injectors, which I can assess).

m;

So, the center point of the two discs was the same, and the angle of inclination also appeared to be the same, although I didn't measure it precisely, but rather just held them side-by-side and compared them visually. That's also why I compared the model numbers, and those were indeed different.

Hello dieselcruiser,

Someone has taken pity on my karma (thank you!), so I was able to put on the blue overalls and can now also participate in the conversation here.

The two large, adjacent scratches on the housing likely do not affect the function of the pump itself. The cause of these scratches is probably due to the introduction of lateral forces by the toothed wheel. Apparently, the front pump bearing is worn. The drive shaft then tilted to the side, and the adjustment ring sitting on it left the marks on the housing. It is possible that the tilt of the drive shaft caused the vane pump to no longer seal properly within the housing, preventing the build-up of fuel pressure in the pump.

I highly doubt that you could tell from a photo whether one rotor head has a steeper attack angle than the other. The maximum lift is likely to be almost the same. A more likely difference would be in the relief areas within the control piston.

I believe that the machining marks significantly hinder the movement of the adjustment ring. When I tried to move the ring with some pressure towards the machining marks in the housing, it felt somewhat rough. After grinding, it worked much better. The theory that the drive shaft is misaligned is contradicted by the fact that the adjustment ring is not connected to the drive shaft at all, but is only guided by the housing. The force applied by the piston for the injection start adjustment to the adjustment ring acts directly in the direction of the machining marks and likely caused the damage due to the lack of lubrication from the biodiesel. The rotary vane pump shows an almost new appearance, which is why I took both this pump and the drive shaft from the AFN pump. In any case, thank you very much for your constructive opinions!