Hi,
I have a CL203 with an M271 engine which keeps throwing an engine light. When I scan it I get P0171 however I don't notice a rough idle or anything detrimental. It came on right after it's MOT which it passed including the emissions. I checked for vacuum leaks and can't detect any. The Short Term Fuel Trim is at 25% at idle, 25% at 2k rpm and 15% at 3k rpm. Goes to 0% when coming of the throttle. The MAF shows 2.1g/s at idle 9.1g/s at 3k rpm. I've measured the post cat lambda at 425mV and this only moves by a few millivolts if I rev the engine. I didn't know the connector for the pre-cat lambda was under the car so I haven't measured that yet and I suspect it may be the cause, however, is there anything else I should check?
Thanks
I have a CL203 with an M271 engine which keeps throwing an engine light. When I scan it I get P0171 however I don't notice a rough idle or anything detrimental. It came on right after it's MOT which it passed including the emissions. I checked for vacuum leaks and can't detect any. The Short Term Fuel Trim is at 25% at idle, 25% at 2k rpm and 15% at 3k rpm. Goes to 0% when coming of the throttle. The MAF shows 2.1g/s at idle 9.1g/s at 3k rpm. I've measured the post cat lambda at 425mV and this only moves by a few millivolts if I rev the engine. I didn't know the connector for the pre-cat lambda was under the car so I haven't measured that yet and I suspect it may be the cause, however, is there anything else I should check?
Thanks