944S2cab
Member
For the last 2 months I have had a problem with acceleration on my 1999 S430 (petrol).
The engine is fine until I press the accelerator beyond approximately half way down at approx. 3500rpm, when it kicks back and seems to have run out of power. I had a fault code relating to the mass airflow sensor and I replaced it (with an aftermarket part as I intend to part-exchange the car). I cleared the fault code and it did not return.
The acceleration problem returned with fault codes relating to voltage on 3 coil packs. I replaced all 8 coil packs (aftermarket) and cleared the codes and they have not returned.
The acceleration problem returned and there was a fault code P0150 relating to the pre-cat left hand oxygen sensor. I fitted a new Bosch sensor and deleted the code but the acceleration problem is still there.
I have just serviced the car. It has new air filters, fuel filter and Bosch spark plugs.
I have obtained the following live data. The first reading is at idle, the second at 3000rpm.
Air mass volume: 8kg/h. 76kg/h
Air flow meter voltage: 1.21V. 2.1V
Throttle valve angle: 2.2 7.2
Injector duration 3.3 3.45 on both banks
Camshaft Hall sensor: 85-170 at idle, same at 3000rpm
Intake manifold pressure sensor: 0mbar 5mbar
Throttle position sensor signal 1: 4.41V 4.14V
Throttle position sensor signal 2: 0.57V 0.84V
Pedal position sensor signal 1: 0.31V 1.46V
Pedal position sensor signal 2: 0.14 0.78
Left O2 sensor pre-cat: -3% 0% voltage: 123mv 216mv
Right O2 sensor pre-cat -1% +1% voltage 641mv 69mv
My diagnostic kit will not give readings for the post-cat O2 sensors for some reason.
If any technician members could give me some guidance on what to do next (apart from take it to the local MB specialist) I would appreciate it.
Thank you.
The engine is fine until I press the accelerator beyond approximately half way down at approx. 3500rpm, when it kicks back and seems to have run out of power. I had a fault code relating to the mass airflow sensor and I replaced it (with an aftermarket part as I intend to part-exchange the car). I cleared the fault code and it did not return.
The acceleration problem returned with fault codes relating to voltage on 3 coil packs. I replaced all 8 coil packs (aftermarket) and cleared the codes and they have not returned.
The acceleration problem returned and there was a fault code P0150 relating to the pre-cat left hand oxygen sensor. I fitted a new Bosch sensor and deleted the code but the acceleration problem is still there.
I have just serviced the car. It has new air filters, fuel filter and Bosch spark plugs.
I have obtained the following live data. The first reading is at idle, the second at 3000rpm.
Air mass volume: 8kg/h. 76kg/h
Air flow meter voltage: 1.21V. 2.1V
Throttle valve angle: 2.2 7.2
Injector duration 3.3 3.45 on both banks
Camshaft Hall sensor: 85-170 at idle, same at 3000rpm
Intake manifold pressure sensor: 0mbar 5mbar
Throttle position sensor signal 1: 4.41V 4.14V
Throttle position sensor signal 2: 0.57V 0.84V
Pedal position sensor signal 1: 0.31V 1.46V
Pedal position sensor signal 2: 0.14 0.78
Left O2 sensor pre-cat: -3% 0% voltage: 123mv 216mv
Right O2 sensor pre-cat -1% +1% voltage 641mv 69mv
My diagnostic kit will not give readings for the post-cat O2 sensors for some reason.
If any technician members could give me some guidance on what to do next (apart from take it to the local MB specialist) I would appreciate it.
Thank you.