Injector calibration with VCDS (Articles)

Adjust IMA-ISA values – TDI injector calibration with VCDS (injector adaptation)

Anyone working on modern diesel engines will eventually encounter piezo injectors. These high-precision parts are factory-measured and classified into groups – the so-called IMA (Injector Quantity Adjustment) and ISA values (Injector Voltage Adjustment). They describe the individual injection behavior of each valve.

Due to manufacturing tolerances, each injector has its own unique characteristics. The engine control unit (ECU) uses these values, along with self-learned correction factors, to optimally calculate the pre-injection and post-injection amounts for each cylinder.

Quote:

Important: IMA-ISA values depend on mileage. An injector with 10,000 km differs from one with 70,000 km. The control unit automatically adjusts the learned values during operation. If the IMA-ISA values are changed, these learned values are reset – the control unit assumes that a new injector has been installed.

When do IMA-ISA values need to be adjusted?

• One or more injectors have been replaced – Attention: Only adjust the modified valves, not the old ones!
  
• The engine control unit has been replaced.
  
• Do not modify if none of the mentioned components have been replaced – not even for practice purposes.
  

The adaptation code – where can I find it?
The code is directly on the injector. Most of the time, it is a 7-digit value.
Exception: 1.2 L engines with Delphi injectors – in this case, there is a 20-digit code present. This value must be converted before being entered, as the control unit only understands hexadecimal values.

Conversion table (code on the injector → converted code)

Code on Injector	Matches	Transformed Code
0	→	00
1	→	01
2	→	02
3	→	03
4	→	04
5	→	05
6	→	06
7	→	07
8	→	08
9	→	09
A	→	0A
B	→	0B
C	→	0C
D	→	0D
E	→	0E
F	→	0F
G	→	10
H	→	11
J	→	12
K	→	13
L	→	14
M	→	15
N	→	16
P	→	17
R	→	18
S	→	19
T	→	1A
U	→	1B
W	→	1C
X	→	1D
Y	→	1E
Z	→	1F

Example:
On the injector, it says: W G 7 6 4 8 8 H E 6 F 7 K 7 U 5 2 C Z 0.
After the conversion, the result is:

Code:

1C 17 07 06 04 08 08 11 0E 06 0F 07 13 07 1A 15 02 0C 1F 00

Now, spaces need to be inserted so that a readable string is created.

Requirements

• The new injectors have been installed, and the IMA-ISA codes are available.
  
• Ignition ON.
  
• Engine OFF.
  

Instructions – Adjusting IMA and ISA values using VCDS

1. Start VCDS and connect to the vehicle.
   
2. [Select] → 01 – Engine
   
3. [Adaptation – 10]
   
4. Now the channels appear:
   
   • Channel: Injector 1 correction value
     
   • Channel: Injector 2 correction value
     
   • Channel: Injector 3 correction value
     
   • ... (other cylinders, with corresponding adjustments up to channel 4 for four-cylinder engines)
     
   
   
5. For each injector to be modified, enter the converted value.
   
6. [Test] → [Save] → [Done, Go Back]
   
7. Turn the ignition OFF, wait 10 seconds, then turn the ignition back ON.
   
8. The values should now be saved. Please review and check the adaptation channels again for verification.
   

Tips

• If the code on the new injector is difficult to read, scanning a QR code often helps (e.g., using the app i-nigma – works on BB, Android, and iOS).
  
• After the adjustment, the previous learned values of the control unit will be erased. The vehicle should then be driven under normal operating conditions for a certain period of time to allow the control unit to recalibrate itself.
  
• No experiments: Only adjust if an injector or the control unit has actually been replaced.
  

If anything is unclear, consult the official VCDS manual or the relevant forums.

See also:
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