Measuring Value Blocks, Reading
Special tools, workshop equipment, testers, measuring instruments and auxiliary items required
- VAG 1551/1552 Scan Tool using VAG 1551/3 adaptor cable
Test Conditions
- Engine Coolant temperature must be 80 °C minimum.
- All electrical consumers must be switched OFF, e.g. rear window defroster.
- A/C must be switched OFF if installed
- Place Transmission Range selector in P or N for vehicles with an automatic transmission.
- No DTCs stored in DTC memory. Checking DTC Memory (Function 02)
Work Sequence
- Connect VAG 1551/1552 Scan Tool. [1][2]Reading and Clearing Diagnostic Trouble Codes
- Ensure that engine is running at idle
- Press 0 and 1 buttons to select Address word 01: "Engine electronics"
Display will appear as shown
Rapid data transfer HELP
Select function xx
- Press 0 and 8 buttons to select Function 08: "Read measuring value block".
- Press Q button to enter input
Display will appear as shown
Read measuring value block HELP
Input display group number xxx
NOTE: Display group 001 is an example to illustrate the sequence.
- Press buttons 0, 0 and 1 to select "Display group 1"
- Press Q button to enter input
Display will appear as shown (1 to 4 Display zones)
Read measuring value block 1 ->
1 2 3 4
- Press -> button.
Display will appear as shown
Rapid data transfer HELP
Select function xx
- Press 0 and 6 buttons to select Function 06:"End output"
- Press Q button to enter input
NOTE: To change to another display group proceed as follows:
Display group 000 at Idle (engine warm, coolant temperature 80 °C minimum)
Display group 001 at Idle (engine warm, coolant temperature 80 °C minimum)
Evaluation: Injection quantity display
Evaluation: Modulating piston displacement sensor voltage display
Display group 002 at Idle (engine warm, coolant temperature 80 °C minimum)
Evaluation: "Throttle position" display
Evaluation: "Operating condition" display
Relevance of figures in 3-digit number block for engine operating conditions:
Display group 003 it Idle (engine warm, coolant temperature 80 °C minimum)
Evaluation: Air mass drawn in (specified) display
Evaluation: Air mass drawn in (actual) display
Display group 004 at Idle (engine warm, coolant temperature 80 °C minimum)
Evaluation: Start of injection (specified) display
Evaluation: Start of injection display (actual)
Display group 005
The values displayed are not useful for Service department troubleshooting.
Display group 006 with ignition switched ON
Evaluation: Brake pedal monitor display
Relevance of figures in 3-digit number block for brake pedal monitor:
Display group 007 with ignition switched ON (engine cold and not running)
Evaluation: Fuel temperature display
Evaluation: Intake Air Temperature display
Evaluation: Engine Coolant Temperature display
Display group 009
The values displayed are not useful for Service department troubleshooting
Display group 012
The values displayed are now useful for Service department troubleshooting.
Display group 013 at Idle (engine warm, coolant temperature 80 °C minimum)
Evaluation: Idle speed smooth running control display
- The fuel injection system is equipped with an idle speed smooth running control. There may be power differences between the individual cylinders (component tolerances, jet drillings, compressions etc.) which are recognized and equalized via selective injected quantities.
- Recognition at idling speed is via the signal from the engine speed sensor which delivers four signals per crank- shaft revolution to the control unit. If the signals are delivered at the same rhythm then all cylinders work the same. If one cylinder is weaker then the crankshaft takes longer for the next half revolution. Conversely a more powerful cylinder accelerates the crankshaft so less time is taken.
- If the Engine Control Module (ECM) recognizes a difference, then the relevant cylinder is given more or less fuel, until the engine runs evenly again.
- The Measuring value block displays the Injection quantity differences of the individual cylinders compared with cyl. number 3 to ensure even idle quality.
- + to mg/H: The relevant cylinder is less powerful than No.3 cylinder and is therefore supplied with more fuel.
- - to mg/H. The relevant cylinder is more powerful than No.3 cylinder and is therefore supplied with less fuel.
Display group 015
The values displayed are not useful for Service department troubleshooting.
Display group 016 at Idle
Evaluation: Additional heater display
Relevance of figures in 8-digit number block for additional heater:
Evaluation: Heater element activation display
Relevance of figures in 2-digit number block for heater element activation:
Display group 19 with ignition switched ON
Evaluation: Modulating piston displacement sensor voltage display
Display group 000 at Wide Open Throttle (test drive in 3rd gear,Engine Coolant Temperature 80 °C minimum)
NOTES:
- When testing ,accelerate vehicle under Wide Open Throttle.
- Measuring values must be printed out or displayed (2nd person required)when engine speed reaches 3,000 rpm.
Display group 004 at Wide Open Throttle (test drive in 3rd gear, Engine Coolant Temperature 80 °C minimum)
NOTES:
- When testing, accelerate vehicle under Wide Open Throttle.
- Measuring values must be printed out or displayed (2nd person required) when engine speed reaches 3,000 rpm.
Evaluation: Start of injection (actual) display
Evaluation: Cold start valve duty cycle display
Display group 008 at Wide Open Throttle (test drive in 3rd gear, Engine Coolant Temperature 80 °C minimum)
NOTES:
- When testing, accelerate vehicle under Wide Open Throttle.
- Measuring values must be printed out or displayed (2nd person required) when engine speed reaches 3,000 rpm.
Evaluation: Injection quantity (driver's requirement) display
Evaluation: Injection quantity limitation via revs. (torque limitation) display
Evaluation: Injection quantity limitation due to air mass drawn in (smoke prevention) display
Display group 010 at Wide Open Throttle (test drive in 3rd gear, Engine Coolant temperature 80 °C minimum)
NOTES:
- When testing, accelerate vehicle under Wide Open Throttle.
- Measuring values must be printed out or displayed (2nd person required) when engine speed reaches 3,000 rpm.
Evaluation: Air mass drawn in display
Evaluation: Manifold Absolute Pressure (Boost pressure) display
Evaluation: Throttle position display
Display group 011 at Wide Open Throttle (test drive in 3rd gear, Engine Coolant Temperature 80 °C minimum)
NOTES:
- When testing, accelerate vehicle under Wide Open Throttle.
- Measuring values must be printed out or displayed (2nd person required) when engine speed reaches 3,000 rpm.
Evaluation: Boost pressure display (actual)
