AFB Injector Timing: Adjustment Guide

Hello,
First of all, I want to give a big compliment to this forum. I've been through many forums, but I've found the most helpful contributions here. So, I've decided to register. And I actually have a question right away:

My engine (Audi A4, year 1999, engine code: AFB) is misfiring at idle, which I suspect is due to an injection timing that is too early. This was also confirmed by the VAG-COM TDI timing diagnostic. After browsing this forum for a few days, I finally felt confident enough to adjust it myself.
So, I adjusted the injection pump slightly, but very late (not through adaptation!!!).
Unfortunately, nothing has changed. Am I correct in assuming that the injection timing adjuster constantly resets the injection timing to the old value, regardless of how I adjust the pump? Even after extreme adjustments and starting difficulties, the values reverted to the old ones after a few seconds, resulting in engine knocking at idle and premature injection timing.
I'm a bit lost right now.
Would it be beneficial to shift the entire characteristic map (target values) towards later timing via adaptation (would be my next step)?

And how do I determine the correct static injection start? According to the Audi repair manual, the injection start should be at 2° BTDC ± 2°, which it usually is, thanks to the injection control valve. I would just like to adjust it properly for a good start.
Did I miss something?

"Sorry if I'm asking in the wrong forum, but as a newbie, I'm not yet allowed to post in the "Diesel - Engine Technology" section."

Best regards, Ronny.

Okay, so the dynamic start time must be within the specified values (see target data), and the rest is controlled electronically. Specifically, it should be between 0 and 4 minutes (but only if the pump is starting late, not when the motor is running normally).

TDI timing is only possible with the newer versions of VAG-COM; otherwise, perform the basic adjustment in group 4 (the pump switches from early to late timing, read the values).

You don't rotate the VP44; you also don't remove the gear, but rather you rotate the wheel on the NW (North West) side! You probably already knew that.

The pump is statically positioned using the north/west and east/west locking mechanisms and a pin.

"Nageln" can indicate either a severely misadjusted fuel pump (outside the normal operating range, which probably isn't the case for you), incorrect valve timing (check with locking mechanisms), worn-out valve guides, or a faulty exhaust valve system (ESD).

You know that the V6 engine can be quite noisy when it's cold, right? Mine, for example, is noisier than my old 1.9 engine with 96 kW.

Good luck.

Adjusted valve timing (check with locking mechanisms), worn camshaft, or a 'defective' ESD.


Okay, I'd check the camshaft. I once had a camshaft misaligned by a few degrees on an AAZ engine (the crankshaft locking pin came loose during timing belt installation, and I didn't notice it right away), and it ran terribly. It had a bad cold start, a bad warm start, very little torque, and the engine ran like an old tractor.

And how do I determine the correct static injection start? According to the Audi repair manual, the start should be at 2° BTDC ± 2°, which it almost always is, due to the injection timing adjuster. I would just like to adjust it properly for a good start.
Did I miss something?


Search function + expert articles -> 'TDI Graph'

Would it be beneficial to shift the entire characteristic map (target values) towards later timing via adaptation (which would be my next step)?


Stop doing that; you risk damage from higher exhaust temperatures (in extreme cases), and it will result in lower efficiency (less power/torque).

Quote:

Quote: And how do I determine the correct static injection start? According to the Audi repair manual, the start should be at 2° BTDC ± 2°, which it almost always is, due to the injection timing adjuster. I would just like to adjust it properly for a good start. Did I miss something? Search function + expert articles -> "TDI Graph"

The graph is likely only available in the new VAG-COM versions for V6 engines; otherwise, use MWB4 -> basic settings. There will be very little information available in the search function for V6 engines. Therefore, it's better to enter the ignition timing dynamically.

I find the term static injection start problematic, as there is no corresponding value for it, but rather locking mechanisms. The value that Khyro mentions is already the dynamic injection start and is adjusted using a graph or a basic setting.

Quick response, respect!

The dynamic fuel injection start occurs at approximately 2° before top dead center (idle, engine warm), as required by the specifications, but it's still misfiring. It's not severe, but it bothers me, and it wasn't present before.

I recently had a complete engine replacement, including new camshafts, an exhaust system, and a fuel injection pump.
That's why I suspect that the pump wasn't properly adjusted.

I turned the rotor of the fuel injection pump. All the gears, timing belts, or similar components remained attached. I only loosened the 3 screws of the crankshaft pulley, as described in the repair manual.

"My TDI timing is already running, and I've seen that it's operating at the upper tolerance limit. What surprises me is that it won't adjust to the ideal line."
I checked the basic settings for group 4, and the values are within the normal range for driving conditions, so everything seems okay, right?

Could you perhaps explain the static setting in more detail? If it's too much, I'll look it up more specifically on Google.

Wenn der Motor kalt ist läuft er schön ruhig, dann liegt der Einspritzbeginn auch im "Früh-Bereich" Erst wenn er wärmer wird und Richtung Spät wandert fängts Nageln an. KomisWhat's up? / What's going on?

And I also have the usual cold start and warm start problems . I will try to compensate for this by adjusting the starting amount.

Best regards, Ronny.

With "static pump start," I mean the setting of the pump at engine start, specifically the first few seconds before any regulation takes place. Surely, this setting must also be correct, right?
Otherwise, the engine is running great! The fuel consumption, top speed, and power are all good.

Sorry, if I seem ignorant, but I am still in the process of learning more about the subject .

Best regards, Ronny.

The start of static funding is determined by the adjustments already made.
You could try disconnecting the connector at the injection nozzle housing for the NBF (No Back Pressure) sensor. It will create an error message, but it shouldn't cause any major issues otherwise. Opel and Ford manage without it entirely when it comes to the VP44 fuel injection pump.

Quote:

The pump is statically adjusted using the north/west locking mechanisms and a pin.

After some "googling" and logical thinking , I finally understood it .

Okay, so I'll set the KW/NW to OT (I don't necessarily need to lock it, right??) and see if I can insert the centering pin into the pump. If the holes match, the "static start of delivery" should also be correct, or?? That's at least how I would solve it . Thanks for the thought-provoking suggestion!!!

Now, I'm only wondering how to move the start of injection in the "VAG-COM TDI Timing" setting away from the tolerance limit and onto the ideal line?! See the Screenshot:
/viewtopic.php?t=13452

Best regards, Ronny.

Have you ever logged Group 4 data during a test drive? If so, under all conditions, excluding minor differences due to changes in load, it should generally be correct. However, if something is wrong within the NHG (National Harmonization Group) range, the EDC (Electronic Diesel Control) or MSG (Motor Steuergerät - Engine Control Unit) will base its calculations on an incorrect actual value and then adjust it to the target value. That's why I suggested disconnecting the connector.

I'll definitely give that NHG thing a try!
And I will also carefully check if the NW, KW, and pump are correctly aligned to ensure that this is the case.

"I already logged Group 4 during a test drive. The actual value consistently followed the target value. It ranged from 2° negative OT at idle to 10.8° advance OT at 4200 RPM. That's why I wanted to try adjusting the fuel map via adaptation to change the target values!"
The throttle position is 100% at idle, and 38% at full throttle and 4200 RPM. Is this okay, or should it be adjusted further towards a "more aggressive" setting?
That would mean the pump is set too far on the "LATE" setting, causing it to run at its maximum speed? *confused*

Or maybe the noise isn't related to the start of the operation, which would mean I'm back to the beginning of my search .

Best regards, Ronny.

Setting the static timing is already worthwhile because it allows you to check the valve timing, including all locking mechanisms. Then, position the distributor rotor ("NW-Rad") of the ESP system to the "middle" position; this will allow you to achieve the 2° BTDC (before top dead center) or the ideal timing curve on the graph. If you position the rotor at its extreme limit, the adjustment range might not be sufficient.

The initial setpoint values are only checked to see if they follow the specified target, they are irrelevant for the dynamic setting (but are important for the static setting, at least twice ), because the pump would have to be "extremely" misconfigured for that to happen.

Here's the translation:

"Just to explain again: the static adjustment is done with the locking mechanisms, while the fine-tuning or dynamic adjustment is done via diagnostics. In my case, the dynamic check is actually unnecessary because it always matches the static adjustment in my system, but a check is still better."

After the dynamic adjustment, you can skip the static adjustment because it's already included. However, if the value is too far outside the tolerance range, it's a good idea to perform the static adjustment first. This is done by removing the vacuum pump, inserting a ruler, and inserting the pump dowel. However, since you might have adjusted valve timing (and this can't be determined this way), it's also a good idea to set the crankshaft and camshaft locking mechanisms as well.

khyro wrote:

Or maybe the noise isn't related to the start of the process, which would mean I'm back to the beginning of my search .

I suspect so; see also my recommendation regarding other things that should be checked.

Your timing is slightly early for optimal values, but still within the tolerance range, so I don't believe it's your fault.

That should be your values, right?
Okay, I understand. Please provide the German text you want me to translate into English. I will only provide the translation.

Yes, those are the values you see at idle with a warm engine.
I would rule out any water damage or electrical system defects, as everything has been replaced and the car has only 17,000 kilometers (approximately 10,500 miles) on it.
Since the timing belt was also replaced, I'm going to check and possibly adjust the settings of the crankshaft, camshaft, and fuel injection pump. I'll also check the knock sensor. Hopefully, something will become apparent there.

Definitely, thank you for the help; this will get me moving forward for now!

Best regards, Ronny.

Oh, so it only happens when the engine is warm. Have you tested your temperature sensors for plausibility? I couldn't find that information here.

Be careful when working with your belt drive; make sure nothing breaks if an adjustment is needed. Also, use a suitable puller and counterholder.

The temperature sensors should be working correctly. I checked the sensors in group 7 while the engine was COLD. All four sensors were showing the approximate outside temperature. After the engine started, they increased plausibly. However, I also replaced the coolant temperature sensor and the mass airflow sensor, as they are known to cause problems frequently.

I hope it's just that the pump is not properly adjusted. If the timing also doesn't match between the crankshaft and camshaft, I'll have to figure something out. To correct this, I lack the specialized tools .

But think positively!!

Best regards, Ronny.

khyro wrote:

I hope it's just that the pump is not properly adjusted. If the NW (negative working) also doesn't match the KW (kilowatt), then I'll have to figure something out. To correct this, I lack the specialized tools .

Postpone that for later. If it doesn't work (due to misalignment or wear on the end of the NW wheel), then re-install the ESP timing belt. I don't think it's related to that, though.

The specialized tool is worth it because then you can do the belt replacement yourself next time. Maybe your local dealer will be helpful.

Dorn KW.
2x Ruler NW
Dorn ESP.
Pliers.
Defaulter.

The first three cost around €50.00 each. I think the rulers were 5mm thick, but I had to sand them down to about 4.5mm (or something like that). The last two cost me about €40 each, so together they were around €80.00. It's not exactly cheap...