Hi All,
J10 1.5 diesel 2008 pre DPF model.
I’m asking about the hesitation/flat spot I’ve always experienced at about 2500/2700 rpm (Owned for 5 yrs) when cruising on the motorway in 6th gear at 75mph ish, nobody has really provided an answer.
Recently I did a google search and it appears it’s not only my vehicle that suffers from this, anyway on to the point somebody suggested it might be the MAF sensor and to disconnect it and see if things improved, so I disconnected mine expecting the engine to stall and the engine management light to come on.
But nothing no stall, no light. In fact she still starts and runs as well as ever.
It’s a Siemens VDO unit, can they be tested? as I suspect mine is defunct !!!
and if is defunct why does it go so well and return a good 44+ mpg around town which is our main usage
Any advice appreciated
Neil
MAF meter issue, help pls
-
lewisbryant
- Posts: 336
- Joined: Sat Feb 23, 2019 7:27 am
- Qashqai Model: Mk.3 Qashqai - J12 (2021+) New Model
Is your initial concern with the flat spot resolve with disconnecting the MAF sensor?
First thanks for replying, my initial answer is yes but I’ve
only completed one high speed journey since disconnecting it yesterday and it did seem to be smoother.
If this is the case what are you saying?
Many thanks
Neil
only completed one high speed journey since disconnecting it yesterday and it did seem to be smoother.
If this is the case what are you saying?
Many thanks
Neil
-
lewisbryant
- Posts: 336
- Joined: Sat Feb 23, 2019 7:27 am
- Qashqai Model: Mk.3 Qashqai - J12 (2021+) New Model
When unplugged the engine ECU reverts back to a back up strategy if youd like, it's like substituted data, so that it can make correct calculations for fuelling. If it has improved then that would suggest the currently fitted MAF sensor is providing the ECU with false readings in certain ranges, these sensors are just a hot wire kept at a certain tempreture and when air passes across it the tempreture drops and it then has to apply more current to get the wire back up to temp, the more current the more air the less current the less the air, so it's a direct relationship between current and mass of air. If the sensor is unable to provide the current to the sensor to heat the wire up because its dirty for instance then the current to heat the wire and the amount of air may no longer be in calibration or sync if you get me. This is my understanding of the system apologies if I get a thing or two incorrect.
The reason you dont get any light on is because I believe it's a 3 trip DTC for a p0101 or p0100 which ever one it is cant remember of top of my head and you dont get any limp mode is because it isnt programmed into the ecu to utilise a fail safe for this DTC. When disconnecting the MAF sensor you also disconnect the intake air temp sensor and this also sets a code in the ecu but again must be a 3 trip DTC with no fail safe.
If you were to do this disconnect on a j11 qashqai euro 6 engine with the digital type MAF sensor you would get an instant DTC for a p0101 with no fail safe and an intake air temp sensor circuit high DTC which does have a fail safe and applies power limitation amongst a few other things. If you got yourself a variable resistor and plugged it into the ground and the sensor wire you can actually simulate the intake temp sensor and clear this fault and then your able to use the MAF sensors back up strategy. I've had to do this once on a juke that had no dtcs and everything was checking out good except the MAF readings.
Sorry if this is long winded I babble and like I said I may be incorrect in some parts feel free to correct anything guys.
Hope this helps and I wouldnt recommend doing the substituting on the j11 unless you know what your doing you could fry the ecu.
The reason you dont get any light on is because I believe it's a 3 trip DTC for a p0101 or p0100 which ever one it is cant remember of top of my head and you dont get any limp mode is because it isnt programmed into the ecu to utilise a fail safe for this DTC. When disconnecting the MAF sensor you also disconnect the intake air temp sensor and this also sets a code in the ecu but again must be a 3 trip DTC with no fail safe.
If you were to do this disconnect on a j11 qashqai euro 6 engine with the digital type MAF sensor you would get an instant DTC for a p0101 with no fail safe and an intake air temp sensor circuit high DTC which does have a fail safe and applies power limitation amongst a few other things. If you got yourself a variable resistor and plugged it into the ground and the sensor wire you can actually simulate the intake temp sensor and clear this fault and then your able to use the MAF sensors back up strategy. I've had to do this once on a juke that had no dtcs and everything was checking out good except the MAF readings.
Sorry if this is long winded I babble and like I said I may be incorrect in some parts feel free to correct anything guys.
Hope this helps and I wouldnt recommend doing the substituting on the j11 unless you know what your doing you could fry the ecu.
