Products which are suitable for recording engine speed can be found in the Workshop Equipment Catalogue.
The devices can be used in conjunction with exhaust emissions testers from various manufacturers within the framework of the exhaust gas emissions test.
Normally, engine speeds for diesel engines are recorded using clamp sensors.
The engine speed is detected via the clamp sensor at an injection line. With the engine running, the line delivers an impulse to the clamp due to the pressure increase. It is therefore important that the clamp is not dirty or oxidised.
Thoroughly clean the point of contact for the clamp sensor on the fuel line, as otherwise, inaccurate or fluctuating engine speed indications may result. The result is then unusable.
The following points must be observed when fitting the clamp sensor:
- The line must be straight at the point of contact.
- The clamp sensor must be positioned as close as possible to the pump or nozzle.
- Grease and oil must be removed.
- The clamp sensor should be fastened securely.
- After fastening, do not turn the clamp sensor.
- Fit the ground clamp to the same line in the vicinity of the clamp sensor.
- Connect the clamp sensor, and only then connect the engine speed cable (danger of short circuit).
As well as engine speed recording via clamp sensor, there is also the possibility of
- optical engine speed recording (at crankshaft or camshaft pulley)
- electronic engine speed recording (at TDC sensor or central connector) and
- engine speed recording by means of measurement device/auxiliary equipment (alternator harmonic characteristic, muffler microphone/structure-borne noise).
Connection
Connection to the test vehicle's electrical system is normally via the cigarette lighter or directly to the battery by means of an adapter cable with battery clamp. These are the only adaptations necessary. The LED illuminates after correct connection.
Connection to Diagnostic Equipment or Smoke Opacity Tester (Sot)
When using the engine speed measuring module as ballast on diagnostic equipment or SOT, the technical data and operating instructions for the diagnostic equipment or SOT must be observed.
Before switching on the ignition, the diagnostic equipment must be connected to engine ground or the battery via the ground terminal in order to avoid the possibility of an electric shock. The manufacturer's instructions must always be observed.
Measurement
For measurement purposes, the idle speed must be held constant for at least 30 s. For the cut-off speed, a holding time of at least 1.0 to 5.0 s is applicable, depending upon the specified nominal value.
Note. The alternator belt tension must be correct.
The Holding Time Tx for Opel Diesel Engines Is 1 S.
In the event that the adaptation or calibration fails to produce a stable indicated engine speed, the alternator must be loaded by: Switching on lights and, if necessary, heated rear screen and additional headlamps (but not those with gas discharge lamps). Switching on electric motors (heater fan) and those with regulator circuit (AC) must be avoided, as these can affect the stability of the engine speed display. The adaptation or calibration must then be repeated.
Compiling the Test Report (Diesel Engines)
Errors can be eliminated using the diagnostic equipment. As a result, parts are then only replaced if it is certain that the signal emitted does not correspond with the nominal value or if the incoming signal cannot be converted. To successfully find and eliminate faults on electronic components, it is essential to have an understanding of the system and to possess the appropriate diagnostic equipment.
Note. Check voltage supply and ground connection
The person responsible for the test must issue a test certificate after the exhaust gas emissions test. The test certificate must contain the following information:
- date, time, testing location, testing device type, EGE software version
- VIN
- Vehicle nominal data, vehicle actual data
- result of visual check on components and engine diagnostic system control lamp - not satisfactory (not OK), - satisfactory (OK)
- Result of the smoke density measurement
- Overall result: - EGE test passed; disc awarded as per appendix IXa - EGE test failed
- Month, year when next exhaust gas emissions test due, signature of the person responsible for the test and, in the case of vehicle workshops approved in accordance with § 47b StVZO, the inspection number.
Other devices must be held in the vicinity of the muffler tail pipe for calibration purposes (approx. 1 m to the side), until a stable engine speed is indicated. In the case of extreme exhaust gas silencing, it may be necessary to select a lesser distance. The device must be held still during calibration.
The device is switched on and connected to the vehicle electrical system. After entering the number of cylinders, the engine is started. It is now necessary to wait until the idle speed has stabilised. A calibration is then performed.
Engine speed measurement module and connection cables must be positioned so that they cannot be damaged by hot or rotating components (muffler, fan, belt pulley).
The engine speed measurement module must be positioned so that it cannot slip due to engine vibration.
In order to recognise the useful signal, the engine speed measurement module normally requires an adaptation phase before the measurement phase. For this purpose, the engine is started and the throttle briefly actuated so that the charge telltale is extinguished. Allow engine to run at idle speed. Adaptation is completed after approx. 30 s.
Accurate engine speed measurements are not possible at all measurement points. The measurement must then be made at another point.