Jonboy274
New Member
Hi all, im new to this forum but im having a problem with this car.
Its a Mercedes C220.Engine: 2143cc 16v Engine code: OM651.911 Blue efficiency AMG sport 168bhp.
The car has had a replacement engine (re-man from Ivor Searle) and a brand new turbo but for some reason under full throttle conditions, the car mis-fires badly. Returning to idle it'll mis-fire for a further 5 seconds or so until it clears and runs well again. This flags up a fault code of P0272 (Teach in of the operating parameters for cyl 4 has a malfunction. There is a general error)
** This only does it under full throttle conditions.**
During this mis-fire, the exhaust gasses get very hot (600*c+) and a horrid exhaust fume smell is produced. Thinking ourselves we may have a blocked exhaust or EGR fault, i removed the exhaust straight from the turbo and the car still mis-fires.
So, again, blocked the EGR pipe at the inlet manifold and also straight out of the exhaust manifold but to no improvement.
So now we go down the route of an injector fault and replaced injector number 4. Re-programmed and still the same fault. Swapped with other injectors and re-programmed but again, no improvement.
Next stage was to check vacuums etc to all the turbo actuators/transducers which again were all good. Checked the wiring to them (all good) and signals from the ecu to them (all good).
The turbo was the same as the original one we removed which has an actuator for the boost pressure control flap (diverting the spent gasses between the 2 turbos) and a waste gate actuator for the low pressure turbo, but no charge air bypass flap switch over valve. (assume this is done internally in the cold part of the turbo because it has no separate actuator for it or transducer or wiring even)
Now if you put a stop on the boost pressure control actuator arm (holds the divert flap open slightly) then mis-fire disappears and the car will rev freely to 4000 rpm +. Great! I thought. But no. Driving up the road you have low down turbo lag, and a fault code for low boost pressure turbo 1. Still drives along at a good speed, but revs limited to 3500 rpm. Still no mis-fire though.
Speaking to various mechanic friends, Snap on technical, Autel technical and RMI technical and performing crank sensor scoping and the duty cycle checks at the turbo actuator transducer and ecu pins, it would appear that the actuator vacuum isn't being expelled quick enough or possibly at the correct time.
Having checked for vacuum exhaust and replacing vacuum pipes etc, we have hit a brick wall.
Just wondering if anyone knows of any fix for this or whether the turbo actuator settings need to be re-set? Can this be a problem with the duty ratio of the boost control transducer or is there a problem with the ECU mapping?
Spoke to Ivor Searle who's only answer is 'take the engine out and send it back to us which obviously is a last resort. Its done 300 miles since the engine change.
The reason for the change was because of a failed oil seal (oil filter housing to block) and the car spat all it's oil out over the A34. So obviously the car was running well before this.
Literally apart from engine, turbo, injector and service items (oil air and fuel filters) the car has all it's original things on it.
I hope you can shed some light on the subject. Thanks for you time reading this long post, but as you can imagine, I'm banging my head against a wall...
Its a Mercedes C220.Engine: 2143cc 16v Engine code: OM651.911 Blue efficiency AMG sport 168bhp.
The car has had a replacement engine (re-man from Ivor Searle) and a brand new turbo but for some reason under full throttle conditions, the car mis-fires badly. Returning to idle it'll mis-fire for a further 5 seconds or so until it clears and runs well again. This flags up a fault code of P0272 (Teach in of the operating parameters for cyl 4 has a malfunction. There is a general error)
** This only does it under full throttle conditions.**
During this mis-fire, the exhaust gasses get very hot (600*c+) and a horrid exhaust fume smell is produced. Thinking ourselves we may have a blocked exhaust or EGR fault, i removed the exhaust straight from the turbo and the car still mis-fires.
So, again, blocked the EGR pipe at the inlet manifold and also straight out of the exhaust manifold but to no improvement.
So now we go down the route of an injector fault and replaced injector number 4. Re-programmed and still the same fault. Swapped with other injectors and re-programmed but again, no improvement.
Next stage was to check vacuums etc to all the turbo actuators/transducers which again were all good. Checked the wiring to them (all good) and signals from the ecu to them (all good).
The turbo was the same as the original one we removed which has an actuator for the boost pressure control flap (diverting the spent gasses between the 2 turbos) and a waste gate actuator for the low pressure turbo, but no charge air bypass flap switch over valve. (assume this is done internally in the cold part of the turbo because it has no separate actuator for it or transducer or wiring even)
Now if you put a stop on the boost pressure control actuator arm (holds the divert flap open slightly) then mis-fire disappears and the car will rev freely to 4000 rpm +. Great! I thought. But no. Driving up the road you have low down turbo lag, and a fault code for low boost pressure turbo 1. Still drives along at a good speed, but revs limited to 3500 rpm. Still no mis-fire though.
Speaking to various mechanic friends, Snap on technical, Autel technical and RMI technical and performing crank sensor scoping and the duty cycle checks at the turbo actuator transducer and ecu pins, it would appear that the actuator vacuum isn't being expelled quick enough or possibly at the correct time.
Having checked for vacuum exhaust and replacing vacuum pipes etc, we have hit a brick wall.
Just wondering if anyone knows of any fix for this or whether the turbo actuator settings need to be re-set? Can this be a problem with the duty ratio of the boost control transducer or is there a problem with the ECU mapping?
Spoke to Ivor Searle who's only answer is 'take the engine out and send it back to us which obviously is a last resort. Its done 300 miles since the engine change.
The reason for the change was because of a failed oil seal (oil filter housing to block) and the car spat all it's oil out over the A34. So obviously the car was running well before this.
Literally apart from engine, turbo, injector and service items (oil air and fuel filters) the car has all it's original things on it.
I hope you can shed some light on the subject. Thanks for you time reading this long post, but as you can imagine, I'm banging my head against a wall...
