Diagnosis
Diagnosis using the HHT
Activation applications
Activation using HHT | Possible symptoms, no DTC's stored | Examples of possible causes in system (refer to corresponding DM) |
Camshaft | Rough idle, poor performance | Adustable camshaft control |
Secondary air injection pump | Excessive emissions | Secondary air injection piping, oxygen sensor, secondary air injection pump |
Injection valve | Rough idle, poor performance | Injection valve, engine control module |
Throttle valve | Idle speed too high, rough idle, motor hunts | Poor idle control, position sensor |
Electric fuel pump | Repairs to fuel system (relieve fuel pressure) | Repairs to fuel system |
Evaporative emission control system | Fuel odor | Purge valve, leak in EVAP system |
Purge control valve Carbon canister | Test EVAP system, check for system integrity | |
Exhaust gas recirulation | Rough idle, high fuel consumption | EGR valve, (binding) |
Air/fuel mixture control | Off-idle or warm-up faults | Ignition coil, air leak, injection valve |
Diagnosis
Diagnosis using the HHT
Activation applications
Activation using HHT | Possible symptoms, no DTC's stored | Examples of possible causes in system (refer to corresponding DM) |
Electric cooling fan | Motor temperature too high | Cooling fan defective, engine control module, wiring |
Ignition control | Rough idle, poor performance | Ignition coil, spark plugs, wiring |
Switchable intake manifold | Poor performance | Switchover valve, vacuum lines, vacuum tank |
Compression test | Rough idle, poor starting, poor performance | Check for mechanical faults |
Supercharger | Poor performance | Supercharger, air flap/air filter motor, engine control module |
Supercharger clutch | Poor performance | Supercharger, wiring, engine control module |
Air intake | Poor performance | Air intake switchover valve/motor, engine control module |
Acitvation functions
Activation using HHT | Function | |
Camshaft | ON | Motor idles poorly (uneven) |
Secondary air injection pump | ON | Oxygen sensor voltage goes to < 40 mV in max 60 s. |
Injection valve | OFF ON | Idle speed drops briefly when an injector is switched off. Idle quality deteriorates. Idle quality improves when the injector is switched on again. |
Throttle valve | OPEN CLOSED | Idle speed increases as throttle angle increases. Idle speed decreases as throttle angle decreases. |
Electric fuel pump | OFF | OFF: Fuel pressure drops and the motor stalls. |
EVAP system | ON | Purge valve ON: Purge valve cycles |
Purge control valve Carbon canister | ON | Test EVAP system, for leaks, engine off. |
Exhaust gas recirulation | ON | Motor runs poorly, stalls. |
Air/fuel mixture control | RICH\\LEAN | LEAN: Idle quality deteriorates |
Acitvation functions
Activation using HHT | Function | |
Electric cooling fan | PLUS/MINUS | Cooling fan can be regulated between 20 and 90%. |
Ignition control | ON | Motor runs somewhat poorly recognizable by poor idle quality. If no change in idle quality, check ignition circuit for faults. |
Switchable intake manifold | ON | ON: Operation of switchover valve is visible under motor cover. |
Compression test | Test for internal cylinder damage. | |
Supercharger clutch Air flap/air filter actuator | ON ON | Supercharger clutch engages Air flap can be heard switching. |
Additional information to the actual value screens
HHT actual value screen | Possible symptoms, no DTC's stored | Possible faults in system |
Testing engine at idle, emissions testing | Complaints of poor performance | Refer to corresponding DM volume |
Testing engine | Test of motor functions Check idle speed control system | Refer to corresponding DM volume |
Engine, cold start | Engine won't start or starts with difficulty | Refer to corresponding DM volume |
Engine, warm-up | Complaints during warm-up | Refer to corresponding DM volume |
Engine performance | Testing on a chassis dynamometer Poor acceleration Poor performance High fuel consumption | Refer to corresponding DM volume |
Cruise control | Complaints with cruise control operation | Refer to corresponding DM volume |
Drive authorization system | Engine will not start | Refer to corresponding DM volume |
Cylinder balance test (smooth running function) | Engine complaints (mechanical, engine management) | Refer to corresponding DM volume |
Compression testing | Engine shakes Engine starts with difficulty Blue exhaust smoke after start up Poor performance | Refer to corresponding DM volume |
Tests completed | After repaired faults | Refer to corresponding DM volume |
Compression Testing
Compression can be tested as an input using the HHT.
A mechanical problem may be present if the difference in engine speed is > 8 rpm for engines 104/112/113, and > 5 rpm for engine 111.
Any engine speed difference will not present itself in the same manner in all engines, so no conclusions can be drawn concerning the affected cylinder.
If the engine speed difference is greater than the set value, perform a compression/cylinder leakage test to determine the affected cylinder.
P07.61-2279-13
P07.61-2280-13
Figure 2
Failed compression test |
Engine 113 |
Example: |
Cylinder 1 330 rpm (max. value) |
Cylinder 4 320 rpm (mni. value) |
Difference 10 rpm |
Figure 1
Good compression test |
Engine 113 |
Cylinder balance test
The cylinder balance test must be performed at idle. If the misfire recognition shutoff threshold is exceeded, a fault will be stored and at the same time the fault count will increases. After repairs, clear the diagnostic memory.
P07.61-2281-13
P07.61-2282-13
Figure 4
Failed cylinder balance test |
Engine 112 |
Fault in cylinder 4 |
Figure 3
Good cylinder balance test |
Engine 112 |
1/s2=Engine speed difference |
between cylinders |
Ignition circuit shutoff
Ignition circuit shutoff can only be performed on Motor 113.
P07.61-2283-13
P07.61-2284-13
Figure 6
Failed ignition shutoff test |
Engine 113 |
Ignition circuit b switched off |
Fault in cylinder 5, ignition circuit a |
Figure 5
Good ignition shutoff test |
Engine 113 |