micra after some opinions

[tonyboy101]

hi all

i have nissan micra 2006 model with k12 engine petrol
code read with snapon solus code p1144 lambda values reached maximum minimum too many times

checked for air leaks

when driving car at about 2000 to 2500 revs on light throttle car holds back / hesitates accelarate hard it pulls through hesitation

fitted new plugs and air filter[very black not been changed for a while]car has 28000 miles on the clock

when hesitation happens min trim level goes to -25%

any ideas

tony

[oldford]

With the trim (which one, STFT or LTFT?) on -25% the mixture is way too rich. Could be a defective Oxygen sensor or a leaking injector or blocking fuel pressure regulator.
Does this vehicle have an Airmass or a map-sensor?

[carvan]

-25 means that the ecu has reduced the amount of fuel as much as it can cause it was told by the front lambda sensor that it was too rich.It could be a fault in the lambda sensor or its wiring or less likley it could be over fueling but due to your lack of power it sounds like mixture is lean,they used to be bad for air flow meter faults but that fault code would not be there for the old air flow meter faults.

[tonyboy101]

With the trim (which one, STFT or LTFT?) on -25% the mixture is way too rich. Could be a defective Oxygen sensor or a leaking injector or blocking fuel pressure regulator.
Does this vehicle have an Airmass or a map-sensor?

many thanks for your reply oldford
the trim level is stft
yes car air mass meter
the vehicle has had new front lambda sensor just before it came to me

[carvan]

You need to check what is hapening to the voltage on the black wire of the front lambda sensor when it is holding back and when it running ok. also what is the long term fuel trim.

[DCD]

Do you have HR16 engine?

[smosha]

I work on these all day, unplug the rear oxy sensor, you will probley find it drive great (mil light on tho) and the front oxy sensor will come back into spec, if so replace the rear oxy sensor, I tend to drill a little 1/8 hole in the down pipe of exhaust as its the build up of water in the exhaust that causes the rear sensor to fail

[tonyboy101]

Do you have HR16 engine?

engine is 1.2
thank you

[oldford]

Smosha is right. Have seen this before where one defective Oxygen sensor disturbs the signal from the other good sensor.

[tonyboy101]

many thanks for all your help i did what smosha and oldford said
replaced sensor worked a treat
once again thank you for all your help
tony