AFB Engine Problems: Get Expert Advice!

Hello, I'm having the following problem with my TDI. It's an AFB engine (2000 A8 2.5 TDI 150 hp) with a Tiptronic transmission.

"This car now has 170,000 km on the odometer. (Since the same engine was also used in the A6, and I'm hoping to find more information here, I'm posting my question here.)"



The engine has no power, it only revs up to a maximum of 2000 RPM, and you can only go faster by shifting early using the Tiptronic system.

He doesn't maintain a steady idle speed; it constantly fluctuates (going up and down, almost stalling and then rising back up to idle speed, creating a consistent sine wave pattern).



The error code indicates: 1. G28 speed sensor (this has been replaced, all wiring has been checked, and the control pins on the torque converter housing are also secure and not bent). So, everything should be fine. However, the error code reappears immediately after being cleared, and it would also explain the engine's behavior.



Where else could I look for the error? Could the problem be related to the engine control unit (ECU) in any way?





Error 2: Faulty fuel injection pump control unit. The error code appeared, was cleared, disappeared for a short time, and then reappeared. The fuel injection pump control unit was checked and is functioning correctly. After installing the control unit, the engine ran properly for a short time before reverting to its previous behavior.



Can the control unit be adjusted to match the pump (even though the pump was completely replaced 3 years ago, you never know)?



I have the feeling that the pump isn't doing what the control unit wants it to do.





Could the problem with the speed sensor be caused by something else?





I am grateful for any help and advice.







Greetings from the Harz region.

Hi Denns!

Based on my gut feeling, in your case, I would start by addressing error number 2.
In this case, I would first completely replace the pump (as a test) and then try again in order to completely rule out the pump as the cause of the problem, including any mechanical issues.
Assuming that the fuel supply is in good condition and the distributor cap is new .

Error number 1 can be recorded as a consequential error of error number 2 in the fault memory, because the engine control unit (ECU) receives measured (and in this case, actual) speed fluctuations that do not correspond to the commands sent to the ESP control unit.

Best regards from Munich!

Quote:

Error 2: Injector pump control unit defective. The error code was present, then cleared, and was briefly gone, but then reappeared. The injector pump control unit was checked and is functioning correctly. After installing the control unit, the engine ran properly for a short time, then reverted to its old behavior.

How long after that did he run properly?

Faulty connectors in the wiring harness; a broken cable is almost the likely cause.

Hello, it probably ran for about 5 minutes, not more. Where do you suspect a cable problem might be?

Greetings from the Harz region.