Leistungsmangel und ultrahoher Verbrauch beim AEL-Motor | Posts 48+

Andi aus dem Ösiland wrote:

The rather leisurely movement could also be due to the fact that the speed of the ESP also changes, and thus the N108 needs to be "timed" for an earlier/later injection start because there is more vacuum in the pump (or is the pressure in the ESP kept constant?)

When accelerating with a relatively constant load, the TV (turbocharger boost pressure) changes only slightly and slowly, as the internal pressure already increases with the engine speed.

When there are load changes without simultaneous speed changes (e.g., cruising -> full throttle in the highest gear), the TV normally makes a significant jump, as seen in the G3 AFN.
If the issue also affects the speed, it makes the situation even more puzzling -> Is the MSG (Main System Board) defective?

Hello.

Quote:

However, I suspect that the OT measured by the EDC is later than the actual OT, and therefore the system is generally adjusted to start injections too late.

IMHO, it's also worth checking, especially if the performance issue appeared after a clutch/flywheel replacement.

Is the intercooler piping already 100% leak-free?

Best regards, Rainer.

In terms of the theoretical aspects, I believe we should also investigate whether a high duty cycle at the N108 actually results in a high current, which could indicate significant phase shift.

In some VAG regulations, the TV (torque value) refers to the periods of power interruption. In such cases, a high percentage value during operation would indicate that the regulation is triggering prematurely!
But that doesn't align with the injection start values that, according to the log, should have been reached... somehow, everything seems to be going in circles .

If the basic pump settings, according to the diagnosis, are correct and the overall behavior is approximately correct, then a misaligned camshaft sensor rotor is unlikely.

However, I also consider it theoretically possible that a damaged optical tachometer (OT) sensor signal could cause a speed-dependent shift between the actual and detected OT, perhaps due to cable damage between the sensor and the engine control unit (ECU), electromagnetic interference, etc.
That would also explain the old error, even with the new engine and replacement MSG, because the wiring harness is probably still the old one, right?

How did the problem arise? Was it sudden, gradual, or did it initially occur only occasionally, and then more and more frequently and for longer periods?

Hello.

Okay, so the wiring harness is still the original one, but it has been checked multiple times and, on occasion, tested with new shielded cables as a "bypass." Most of the time, and always so far, this has not produced any noticeable results.

I would rule out the flywheel as the cause, because the same symptoms occurred on the new motor with the new clutch pack as they did on the old motor.

The N108 TV only displays the ratio of off-time to on-time (0% = off => early; 100% = on => late). The voltage, measured with a multi-phase oscilloscope, is almost the same as the average voltage during the on-time. The waveform is a rectangular curve.

The N 108 is simply a "1-0" valve (either open or closed; there is no intermediate value), and the pulsing action is used to maintain any desired value between those two extremes.


The whole problem started when both boost pressure hoses ripped due to age. Since the hoses were very expensive, I continued driving like that for a while, even though the performance was significantly reduced. However, the fuel consumption didn't change at that time.
Then, suddenly, the pump belt broke, and the car stopped (after only 55,000 km after the belt replacement). Both belts were then replaced again. Since then, the fuel consumption has been high, and the performance has been reduced. Months later, the car stopped again => the fuel injection pump was defective. The first one lasted only 2 weeks, then the second lasted about 4 weeks before failing. The third one has now lasted almost two years, but with the problem of reduced power and extremely high fuel consumption.
"In the meantime, the exhaust manifold and turbocharger have been replaced multiple times because they literally burned out. All hoses have been replaced or checked. The coolant and its hoses have been pressure tested (checked for leaks at 2.25 bar). The fuel injection pump is new, the EGR valve is new, the EGR control system is new, the engine control unit (ECU) has been replaced multiple times, etc...."
Just before the "lucky streak" ended, the vibration damper broke apart, which in turn damaged the timing belt again. So, everything had to be replaced once more.


Well... a few months later, the engine mounts failed. Then, a completely new engine was installed.



The more I delve into the intricacies of fuel injection and EDC (Engine Diagnostic Control) systems in AEL engines, the more illogical the troubleshooting process becomes, because some data and values contradict each other or even exclude each other.



I'm going to keep fighting for a little while longer.


Best,
krissi

Kristian wrote:

Suddenly, the pump belt broke

, and the car stopped (after only 55,000 km after the belt replacement). Both belts were then replaced again. Since then, there has been high fuel consumption and reduced power. Months later, the car stopped again => the fuel injection pump was defective. The first one lasted 2 weeks, then the second lasted about 4 weeks before it failed. The third one has now lasted almost two years, but with the problem of lacking power and extremely high fuel consumption.
That smells like a misconfiguration during the first fuel pump replacement, which has been going unnoticed ever since -> typical of a workshop.
"However, I don't know the adjustment procedure for the 5-cylinder engine. You would have to experiment yourself and (theoretically) try to deliberately make incorrect adjustments, so that the error is as inconspicuous as possible."

Edit:
Or should the NBF nozzle have been incorrectly positioned in a cylinder since the last pump replacement, and were the injection lines simply bent to fit?
With only 72° crankshaft offset in the 5-cylinder engine (instead of 180° in the 4-cylinder), there are, in my opinion, already theoretical possibilities to provide a correspondingly advanced ignition timing signal, which is not entirely implausible }, but constantly pulls the injection timing towards a later injection.
Alternatively, individual fuel injection lines between the pump and the cylinders might be swapped, and the NBF (Noiseless Fuel Injector) might be located in the correct cylinder (do the lines from the pump lead to the cylinders in a circular sequence according to the firing order?).

When starting, the NBF signal is ignored -> it could still start normally if the pump is adjusted correctly.

Perhaps an owner of a properly functioning AEL (presumably a specific type of engine) could post where their NBF (likely a component) is located, and how the fuel injection lines are connected between the pump outlets and the cylinders.

hello,

Okay, the NBF (presumably a fuel injector) is in the correct position (cylinder 4), and all the other injectors are properly connected to the ESP (Electronic Stability Program). The injector housing is bent, and it's impossible to bend the connections in a way that would allow you to connect two or more injectors to different locations than what the bending radii allow. In any case, everything looks straight and parallel.


Regarding the reference, the pump settings are incorrect and causing delays.
I used to think the same thing, but I insisted on having a complete engine adjustment done, which didn't change anything. Even after having the crankshaft oil seal replaced (which requires removing the vibration damper and timing belt), there was no change in the symptoms.

Since the same errors are present in the new engine, I'm also ruling out a misconfiguration here (especially because this is the third different workshop that's performing the initial setup).

Today, I tried disconnecting the crankshaft speed sensor while the engine was running. The engine then briefly increased its speed and immediately shut off. Afterward, the ESP (Electronic Stability Program) started making strange, periodic noises that faded in and out. It sounded almost like a solenoid valve being activated with a varying frequency.

As far as I remember from the manuals, the NBF should serve as a backup for the speed sensor (or was it the other way around?). I'll do some more research.

"I'm quite familiar with the injection timing settings for the 5th cylinder, even when I'm not actively working on it, as well as the basic settings. I also know where mistakes can be made, where mistakes are commonly made, and what the consequences of those mistakes are."

"On the old engine, there was this inexplicable phenomenon: if you (forgive me for saying this, and you too...) would rev the engine to 4200/4500 RPM in first or second gear while it was completely cold, and then try to let it idle (e.g., at a traffic light), the engine would sputter and run very rough, as if it were only running on three cylinders, and it wouldn't respond to the throttle. Then, after a few seconds, it would stall. Restarting the engine was impossible for the next 5-7 minutes, even with constant cranking. The first restart attempt would result in a huge cloud of black smoke (approximately 25-30 meters in diameter). Consequently, the back of my car was always completely covered in soot."
The error message displayed was "NBF," indicating an implausible signal, possibly due to a short circuit or interruption, and occasionally, a problem with the injection start control.
Neither Audi nor Bosch, nor anyone else, could explain this phenomenon or pinpoint its cause.

The new engine definitely doesn't (but it's only been tested once!).


Okay... I'll do some research on the Audi.

Best regards, Krissi.

Kristian wrote:

so, the NBF is in the correct position (cylinder 4), ... Regarding the reference, the pump settings are incorrect and causing delays. I used to think that too, but then I insisted on having a complete engine tuning done, but it didn't change anything at all. .

Well, if a defect x has existed precisely since the work y was performed, then I assume that x is a consequence of y.

Could the crankshaft position sensor on a 5-cylinder engine possibly be mounted on the pump instead of the crankshaft, and was it perhaps installed incorrectly?
When I look at the signal processing for the 4-cylinder engine with the crankshaft sensor wheel (2 TDC marks spaced 180° apart), it's difficult to directly apply that to the 5-cylinder engine without significant modifications (the spacing is 72°, but only every other mark is counted as a TDC, or something like that...?).

Therefore, I would likely connect the sensor to the pump or the NW (negative working point), or at least install an additional sensor there, which would facilitate the idle speed control and the association of the NBF (negative brake force) signal with the correct cylinder.

EDIT:
I checked, and the 5-cylinder engine also only has the crankshaft position sensor.

Hmm, it could also be that the catalytic converter or the muffler is clogged, which could cause back pressure! A friend of mine had the same problem recently with his T4 ASV – the fuel consumption was insane, up to 16 liters per 100 km. The cause was a clogged catalytic converter! I simply removed the catalytic converter to check (it was very loud), and sure enough, the acceleration was better! I had the catalytic converter cleaned and reinstalled, and it worked wonders!

Hello,

@ T3Surfer

The check happened a long time ago... it wasn't clogged.
While a few small areas were blocked, the total affected area was less than 5%.

Despite that, I managed to mill away approximately 1 mm of material in front of the catheter insertion point, ensuring that all the tubes were clear again.

The result was no noticeable effect on performance or fuel consumption.


Best,
Krissi

Hello,

@ Ulf

I simulated the N108 component using a resistor (75 ohms, 3 watts) and disconnected the connector.

Result = ENGINE IS KNOCKING LIKE A COLD TRUCK IN WINTER !!! Otherwise, N O T H I N G !!!

Neither an increase in performance was noticeable, nor did the consumption decrease.


N108 controls the pump even when the connector is unplugged.


"Driving with the 'original chip' is definitely not fun; you simply don't get anything below 2400 RPM. Even though the boost pressure is already at 0.7 - 0.8 bar."

It's simply not possible to achieve "burnout" from a standstill without revving the engine to its maximum RPM (even with the claimed 290 Nm of torque at 1900 RPM)!!

Anger and frustration are slowly building up.


Well then...

Krissi.

Kristian wrote:

I simulated the N108 using a resistor (75 ohms, 3 watts) and unplugged the connector. Result = ENGINE IS KNOCKING LIKE A COLD TRUCK IN WINTER !!! Otherwise, N O T H I N G !!! Neither an increase in performance is noticeable, nor did the consumption decrease.

Too bad, but it was once a conceivable approach...

Assuming the entire timing of the engine control unit is correct, what other causes could be stealing power and simultaneously reducing efficiency (leading to increased fuel consumption)?

-> Compression loss (likely resolved -> no).

-> Narrow sections in the fresh air or exhaust path (have you really checked everything?)

Hello Ulf,

The intake passages have been checked, and nothing is blocked or being pushed in, either during normal operation or when the intake is activated ==> this has been checked multiple times before.

The exhaust system was also checked, especially the catalytic converter, but nothing unusual was found there.

Yesterday, I performed another chemical cleaning of the fuel injection system. The fuel gauge was at the second mark before the reserve, and I added 2 liters of cleaner. This caused the engine performance to decrease even further, and it started to smoke slightly during strong acceleration. After refueling, it returned to normal as it was before.

Starting from low RPMs, it struggles and takes a while to build power (1700-2400 RPM). Around 2600 RPM, it starts to accelerate a bit faster, and from 3000 RPM, it really takes off, reaching 4400 RPM. At 4600 RPM, the "handbrake" is clearly applied to the engine, which then stays at 4800 RPM (1st through 5th gear; 6th gear only reaches 3400-3500 RPM).

"It already feels like cramping" in the wrist when you're on the highway and pushing it (around 215 km/h according to the speedometer, but GPS shows 203-205 km/h), especially when going slightly downhill and you get casually overtaken by a Polo TDI, which I experienced today!

I have a feeling I'll never get this thing working again!

Best,
krissi

Kristian wrote:

I have the feeling that I will never get this thing to "work" again!!

Well, what can you say... I'm still wondering why the problems started exactly when the first pump was replaced.
Coincidence? In my opinion, very unlikely.
I'm not sure where all the bolts and screws need to be loosened when replacing the fuel pump on this car.

Regarding pump replacement...

The engine is set to the first cylinder (the TDC mark on the flywheel aligns with the clutch housing, and the TDC mark on the flywheel is opposite the injection pump).

Then, only the rear belt is loosened, or the tensioner is loosened, the belt is removed, and the gear on the pump is unscrewed (it has a slot and a spring, so it can only be in one position). Then, loosen the mounting screws of the pump, and you will have the pump in your hand (only if you have also loosened all the connections on the pump beforehand!! ).

Installation, but reversed.

Adjustment is performed using the two timing marks on the flywheel and the injection pump flywheel. Subsequently, dynamic adjustment of the pump is carried out.

It's very easy to replace that part.

The two previous pumps failed due to a technical defect. In the first instance, the car simply stopped and the engine immediately turned off. In the second instance, it stopped accelerating, and when the accelerator was fully pressed, the engine only reached 1400 RPM without any power. The engine immediately turned off when the clutch was engaged. However, fuel was still coming out of the fuel injectors.

Krissi.

How about the fuel system? Have you installed a new fuel pump yet?

Best regards, Mario.

Hi,
It does not have a pre-lift pump.
The OT marking on the ESP is not in the correct position; it is clearly located to the side of the OT marking.
Ideally, to adjust the NW (likely referring to a specific type of engine or component), you should loosen the rear wheel. However, this can be awkward. If these things are no longer working correctly, the engine 1. might not start, and 2. you should notice it during dynamic adjustment.