Engine 120 LH-SFI

When diagnosing starting or warm up complaints, do not check engine at operating temperature, instead proceed according to specific complaint.

Diagnostic plug (060) to diagnostic socket (X11), disconnect connector "A" from DI control module and connect plug (077) in between Diagnostic plug (060) to dual ignition adaptor (055) Knob to position "T1/1 & T1/2" Plug of dual ignition adaptor (055) to diagnostic socket (X11) 2) TN signal/on-off ratio signal connector 3) Trigger clamp (061) on ignition cable "1" Kilovolt clamp (062) and (063) on ignition cable "4" of ignition coil T1/1 and T1/2 Oil thermometer (064) in engine oil dipstick tube DC inductive clamp 1) (065) to battery G1 ground Exhaust vent hose (014) to exhaust pipe Vacuum connection with Y-adapter (068) to DI control module (N1/3) Vehicle data Engine oil temperature approximately 80 °C connect, disconnect connect, disconnect turn connect, disconnect connect, disconnect connect, disconnect connect, disconnect insert, remove connect, disconnect connect, disconnect connect, disconnect enter. warm engine up.

The DI control modules on model 129.076 are located in the engine compartment on the left wheelhousing. The 9-pole diagnostic sockets (X11/2, X11/3) are above the DI control modules (N1/4, N1/5). The assignment of the components to the respective ignition circuit is as follows: The DI control module (N1/4) and the diagnostic socket (X11/2) for ignition circuit T1/2 (cylinders 7 - 12) are in the front, as viewed in the driving direction. The connectors "A" and "B" are easily accessible (Figure 6 and 8). The DI control module (N1/5) and the diagnostic socket (X11/3) for ignition circuit T1/1 (cylinders 1 - 6) are in the rear, as viewed in the driving direction. The connectors "A" and "B" are not accessible. The hot wire MAF sensor must be removed by opening 2 clamps on front of the air filter housing to make the test connections. The MAF sensor together with the formed hose (leading to the throttle valve) can then be pushed aside. The connectors "A" and "B" of the DI control module (N1/5) are now accessible and the necessary connections to the TN signal/on-off ratio signal adaptor can now be performed. The MAF sensor must be installed again for the engine diagnosis, since otherwise it can lead to interferences in the engine performance. The location of the ignition coils is similar to that of model 129 with engine 119. The outer ignition coil belongs to ignition circuit T1/2 (cylinders 7 - 12), the ignition coil towards the engine belongs to ignition circuit T1/1 (cylinders 1 - 6).

Testing with dual ignition adaptor (055) The dual ignition adaptor provides engine diagnosis on engines with dual ignition systems (engine 120) when using the Bear DACE (Model 40-960) engine analyzer. With the dual ignition adaptor (055), the single ignition circuits T1/1 and T1/2 are combined to a 12-cylinder ignition circuit. This enables the display of the single circuits and the complete ignition circuit on the oscilloscope. Next to the standard measurements, the diagnostic measuring methods for dynamic compression test, idle quality test and ignition system analysis can be performed. The switch on the dual ignition adaptor allows the selection of measurements on a single ignition circuit, for example: dwell angle, ignition timing, on-off ratio and voltage values of the primary/secondary ignition circuit. In the total display (switch position T1/1 & T1/2) with the osilloscope in the parade setting, the ignition impulse of ignition circuit T1/1 is shown first. At the end of the fade-out process, switch over to ignition circuit T1/2 occurs and according to firing order the next cylinder, including dwell and current draw are displayed.

	Engine analyzer		Switch position Dual ignition adaptor (055)
	Cyl. number	Trigger clamp
Dwell angle	6 cylinder	Cylinder 1	T1/1 or T1/2
Ignition timing	6 cylinder	Cylinder 1 Cylinder 12	T1/1 T1/2
On-off ratio	12 cylinder	Cylinder 1	T1/1 or T1/2
Ignition oscilloscope	12 cylinder	Cylinder 1 Cylinder 1 Cylinder 12	T1/1 & T1/2 (possible only up to 4400 rpm) T1/1 firing order 1 - 5 - 3 - 6 - 2 - 4 T1/2 firing order 12 - 8 - 10 - 7 - 11 - 9
Compression	12 cylinder	Cylinder 1	T1/1 & T1/2
Idle quality	12 cylinder	Cylinder 1	Idle quality test. Set engine analyzer to TN signal

Equipment

Engine analyzer 1)	Bear DACE (Model 40-960) Sun MEA-1500 MB
Dual ignition system adaptor	Bear 43-322

1) Available through the MBUSA Standard Equipment Program.