TD5 disco 2 maf and ambient air temp sensor

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Dieseldog57

Member
Posts
13
Location
Nottingham, UK
Hi everyone, just got myself the britpart lynx diagnostics. Ran fault clearing then re read codes and I’m getting ambient air temp of 119.9c and 0 on the maf sensor with it plugged in. Checked the wiring and the fuses but all seem okay. Could the maf be faulty and still read 0?? Cheers in advance. 05C2B702-0147-437A-81F1-E008E587F0D0.jpeg
 
Classic test is to drive with it disconnected. If things get/feel better than you know you've got a problem!
But SF will tell you!
 
Dieseldog57 said:
Disconnected it exactly the same result. Only improvement is cleaning the map however I’ve also found out the turbo wastegate actuator is faulty
Click to expand...
"Right. Don't look like the Maf then." (I can hear SF's teeth grinding from here. Of course there is prolly a problem with it, it ought to give some sort of reading, :rolleyes::rolleyes::rolleyes: have you tried cleaning it?)
The Map/IAT if dirty or fubar will make a big difference which you can prove by disconnecting and then driving.
If the wastegate actuator is sticky or you have lost nuts etc then it will lead to the ECU reading it as over-fuelling and putting you into limp-home mode, until you switch off then restart.
Faulty how? Just stuck at the turbo?
Keep us in the picture.
 
If I disconnect the map sensor (the one on the left of the engine as you look at it) it runs really slow. If I disconnect the maf it runs the same, not tried the one just above the air filter itself tho. The wastegate isn’t seized but when I run the “actuator test” in lynx it doesn’t move but I can hear it clicking somewhere. Will deffo keep you updated :)
 
Dieseldog57 said:
If I disconnect the map sensor (the one on the left of the engine as you look at it) it runs really slow. If I disconnect the maf it runs the same, not tried the one just above the air filter itself tho. The wastegate isn’t seized but when I run the “actuator test” in lynx it doesn’t move but I can hear it clicking somewhere. Will deffo keep you updated :)
Click to expand...
Hi, I put this up not cos I agree with it but becos I want to be sure we are talking about the same sensor.
the Maf is a big cylindrical thing between the air filter and the rest of the inlet system.

So you'll see it here. The reason I have done this is cos you have me confused with the "not tried the one just above the air filter itself tho."
To me the only thing "above" the air filter is the bonnet! :rolleyes: Do you mean the AAP sensor?
If the wastegate actuator is jammed then as you try to accelerate up a hill for instance, the engine will just refuse to climb up the revs, like running into a very strong headwind.
I have Foxwell so cannot speak for Lynx.
 
Hiya mate, my apologies I didn’t explain myself properly. Yes the large sensor in the intake pipe I’m referring to as the maf, yes the aat sensor is in the filter part of the air box. I’m going to take the heat shield off the turbo and check the wastegate arm itself by removing the actuator arm. The symptoms I have are extremely low power almost stalling when going up hills but once she reaches 2500 revs she takes off. I have a genuine LR Maf sensor coming and AAT sensor as this is reporting 119c. I have also purchased a turbo wastegate actuator but I have a feeling this may no actually be faulty now. I did an actuator check in lynx and heard clicking from somewhere under the bonnet. Thanks once again for all
Your advice and help :)
 
Dieseldog57 said:
Hiya mate, my apologies I didn’t explain myself properly. Yes the large sensor in the intake pipe I’m referring to as the maf, yes the aat sensor is in the filter part of the air box. I’m going to take the heat shield off the turbo and check the wastegate arm itself by removing the actuator arm. The symptoms I have are extremely low power almost stalling when going up hills but once she reaches 2500 revs she takes off. I have a genuine LR Maf sensor coming and AAT sensor as this is reporting 119c. I have also purchased a turbo wastegate actuator but I have a feeling this may no actually be faulty now. I did an actuator check in lynx and heard clicking from somewhere under the bonnet. Thanks once again for all
Your advice and help :)
Click to expand...
Best of luck with sorting it out!
 
Dieseldog57 said:
....and AAT sensor as this is reporting 119c
Click to expand...
You are in a bit of confusion here, there is no AAT sensor, on Eu3 modells it is AAP/T sensor on the airbox but the temperature reading of this one is not covered by diagnostics, the only reading which you can get from that is ambient pressure. The 119C reading is INLET air temp which is output of the MAP/IAT sensor. According to the readings you described in the first post(with the correction that you can't get ambient temp reading) you need a new MAF(which seems covered) and a new MAP/IAT sensor generally named only MAP.

here's some info:

the figures are based on many live tests and official data from various documents, so:
(for all the presented figures +/- 5% is acceptable)

MAF(air flow) = 55-65 at idle growing with revs up to 600 or above at 3000+rpm under heavy load, at 680 the MAF drops to 0 and the ECU reduces fuelling(turbocharger overspeed protection)

AAP(ambient pressure) = real ambient pressure on barometer in kPa, around 100 must drop up to 2 units to 3000+rpm, more decreasing of that value related to the acceleration should indicate that the air beyond the filter is less than required.

AAT(ambient temp) -only Eu3/15-16P engines = real ambient temp on thermometer (not shown by diagnostics)

MAP(manifold absolute pressure) should be very close to AAP at idle growing to 230 at full load

IAT(inlet air temp) = AAT + 10 to 30 depending on outside temp, engine coolant temp and boost(meaured with coolant gauge at middle)...also it can be much higher if non-cooled EGR is still fitted

COOLANT TEMP = 70 - 115 gauge stays at the midddle, the gauge will go to red zone only at 120 and the electric cooling(aircon) fan kicks in at 110 and stops at 105

FUEL TEMP = around 10 - 20 less than coolant temp depending on ambient temp

THROTTLE
ACCEL. WAY 1 - about 0.3V with the pedal released, about 4.7V with pedal to the maximum position
ACCEL. WAY 2 - about 4.7V with the pedal released, about 0.3V with pedal to the maximum position
ACCEL. WAY 3 – this track must have values very near to the second track.(only 15P-16P engines)
ACCEL. SUPPLY – this value must stay between 4.9 a 5.1
* an up to +0.5V for WAY 1 and -0.5V for WAY 2 are accepted

IDLE ESPEED = 750rpm

IDLE SPEED ERROR – This is a calculated value that shows the difference between the idle speed and the real drive demand
 
Last edited:
Thankyou so much!! So the sensor that’s the first sensor in the air box (downstream of the Maf sensor) what does this do?? I’m going to pick my Maf up on Monday so I’ll enquire about a Map sensor also. I did clean this up and it improved things a little. Cheers again.

sierrafery said:
You are in a bit of confusion here, There is no AAT sensor, on Eu3 modells it is AAP/T sensor on the airbox but the temperature reading of this one is not covered by diagnostics, the only reading which you can get from that is ambient pressure. the 119C reading is INLET air temp which is ouput of the MAP/IAT sensor. According to the readings you described in the first post(with the correction that you can't get ambient temp reading) you need a new MAF(which seems covered) and a new MAP/IAT sensor generally named only MAP.

here's some info:

the figures are based on many live tests and official data from various documents, so:
(for all the presented figures +/- 5% is acceptable)

MAF(air flow) = 55-65 at idle growing with revs up to 600 or above at 3000+rpm under heavy load, at 680 the MAF drops to 0 and the ECU reduces fuelling(turbocharger overspeed protection)

AAP(ambient pressure) = real ambient pressure on barometer in kPa, around 100 must drop up to 2 units to 3000+rpm, more decreasing of that value related to the acceleration should indicate that the air beyond the filter is less than required.

AAT(ambient temp) -only Eu3/15-16P engines = real ambient temp on thermometer (not shown by diagnostics)

MAP(manifold absoolute prssure) should be very close to AAP at idle growing to 230 at full load

IAT(inlet air temp) = AAT + 10 to 30 depending on outside temp, engine coolant temp and boost(meaured with coolant gauge at middle)...also it can be much higher if non-cooled EGR is still fitted

COOLANT TEMP = 70 - 115 gauge stays at the midddle, the gauge will go to red zone only at 120 and the electric cooling(aircon) fan kicks in at 110 and stops at 105

FUEL TEMP = around 10 - 20 less than coolant temp depending on ambient temp

THROTTLE
ACCEL. WAY 1 - about 0.3V with the pedal released, about 4.7V with pedal to the maximum position
ACCEL. WAY 2 - about 4.7V with the pedal released, about 0.3V with pedal to the maximum position
ACCEL. WAY 3 – this track must have values very near to the second track.(only 15P-16P engines)
ACCEL. SUPPLY – this value must stay between 4.9 a 5.1
* an up to +0.5V for WAY 1 and -0.5V for WAY 2 are accepted

IDLE ESPEED = 750rpm

IDLE SPEED ERROR – This is a calculated value that shows the difference between the idle speed and the real drive demand
Click to expand...
 
Dieseldog57 said:
So the sensor that’s the first sensor in the air box (downstream of the Maf sensor) what does this do??
Click to expand...
The sensor on the airbox lid is generally named AAP(ambient air pressure) sensor but on Eu3 modells it has an additional output for AAT(ambient air temp) too but this is not shown dy diagnostics, the default for the IAT side of MAP sensor is 120C hence you get that 119 which is within the error range and cleaning the sensor would not help that, this is a very important sensor so go for genuine LR but if you can't afford that buy only Bosch
 
I dont know what V reg means so without EGR if it's Eu2 the MAP sensor is the most important and if it's Eu3 then the MAF comes into play too
 
I bought my AAT sensor replacement directly from LR dealers.... reasonable price tbh. Stopped the ECU throwing up AAT faults.
 
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