Early 1Z Injection in LL/TL: Troubleshooting

Hi,
"In my 1Z engine (Audi 80 B4, control unit MSA 12, 028 906 021D, SG, D21), I observe at operating temperature, at idle and under partial load up to approximately 2000 rpm, a difference between the target and actual injection start timing of up to 1.5°. The engine is misfiring slightly and runs somewhat harshly at idle. The control of the injection start valve is almost at its maximum late position."
Basically, the injection start is a bit late. The tolerance range used, "all 1Z >1994", matches the tolerance range specified in my Erwin (siehe Fehlerdatenbank) repair manual.
Log data recorded during operation sometimes shows a noticeable delay in the actual value catching up to the target value.
When I mechanically adjust the ESP further towards "late" in its basic setting, the setpoint/actual difference decreases during normal operation. I only bring it close to zero when I set the injection start significantly outside the tolerance range towards "late." In that case, a difference in the engine noise during the transition between the basic setting and normal operation can be heard.
My initial suspicion is a problem with the fuel injection timing valve. However, this doesn't explain why the basic setting shows a late timing, while the actual value in normal operation shows an early timing. In both cases, the control should be fully set to "late" according to the observed values.
The attachments contain logs and VAG Scope data for operation with a late start of injection (injection timing 2, EZ_2) and with an injection start that is well within the tolerance range (injection timing 3, EZ_3). Does anyone here have any further information?
Best regards,
Herbert.

Hi,

You can leave everything as it is. If the engine is making a knocking sound, it's definitely not coming from the logged values.

It's possible that your fuel injection pump is simply worn out. More interesting would be whether the target and actual values for fuel injection timing roughly match when the engine is at full throttle and 4000 rpm.

Please also keep an eye out for potential timing belt crankshaft pulley issues (loosening/shearing) on the 1Z engine.

Best regards, Rainer.
PS: The current version of VCDS is 908.0, which can be downloaded from your customer account.

Hi,
Analysis of log files under full load (highway driving, approximately 4000 RPM) shows: the actual value for injection timing fluctuates slightly around the target value. To me, this looks perfectly normal. The control signal is slightly below 90%. Individual peaks reach 96%.
When the gas pedal is released, the actual behavior seems to be slightly off. The acceleration from 60 km/h to 100 km/h is slightly better than specified.
I will continue to monitor the small age spots, as long as no other problems arise.
When the engine is idling, I measure approximately 14 volts at the ESP (Electronic Stability Program) control unit, specifically at the valve for fuel injection timing (in the normal range and in the basic setting).
The central bolt on the stabilizer bar is fine; my car came with the improved type from the beginning. Still, thanks for the tip!
Best regards,
Herbert.