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Renault Laguna II V6 - Air temp sensor

5K views 5 replies 3 participants last post by  polecat 
#1 ·
Any idea if it's ok to leave the air temp sensor disconnected,
it's located in the air duct between the air filter and the throttle body on the V6 lag II
will the other sensor's compensate for this being disconnected eg coolant, lambda & map sensors.

The reason I ask is because the car runs a hell of alot better with the air temp sensor disconnected, no flat spot's or hesitance.
 
#3 ·
Hello PC, I just spotted this but unfortunately don't know the answer. As you have noticed that reconnecting the air sensor relieves the symptom, I would deduce that it is the cause. I think I have read as much elsewhere but can't, for the life of me, think where. I think it was advised not to leave the MAF off indefinitely, but I can't say why.
 
#4 ·
Hi there vass
I don't think we have a MAF fitted to the V6, it's the MAP we have, got this from a web site "making sense of sensors"

MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR. This sensor is mounted on or connected to the intake manifold to monitor intake vacuum. It changes voltage or frequency as manifold pressure changes. The computer uses this information to measure engine load so ignition timing can be advanced and retarded as needed. It performs essentially the same job as the vacuum advance diaphragm on an old fashioned mechanical distributor.


MASS AIRFLOW SENSOR (MAF). Mounted ahead of the throttle body on multiport fuel injected engines, this sensor monitors the volume of air entering the engine. The sensor uses either a hot wire or heated filament to measure both airflow and air density.

Its the air temp sensor that I had disconnected,not the MAF or MAP.
The car is coming up for it's MOT on the 14th of feb so I took it in today to see if the emissions were ok, maybe this would point to a bad lambda sensor if it failed this test, everything checked out ok

lambda min limit 0.970 max 1.030 actual value 1.002
HC ppm was 4, CO was 0.008 fast idle test

Natural idle CO was 0.005

I am at a loss with this one, and so are Renault, Mr computer is not giving them any fault code's, so all they can do is start chucking parts at it :crazy: .
So I will have to look for a good local diagnostics center.
I asked at the MOT center if they could recommend one
they did'nt seem to have a good word for any of them around here, "sure they have the diagnostic equipment but they dont know how to use it".
:(

Well at least it passed the MOT
 
#5 ·
You will have a MAF (or airflow meter) and a MAP sensor fitted on to your car somewhere,even if it's built in to the throttle body).

Does the engine management light come on when the air temp sensor is disconnected?.

If so then the ECU runs on a set programme which ignores the information it gets from certain other sensors.This can make you think that one sensor is the problem when in fact it is another.

If possible,get the readings from the sensor checked,either as part of an ECU live data scan(an independant garage with the right equipment can do this),or getting the correct resistance readings and comparing them with different temperatures.
 
#6 ·
Cheers lagdti
No the engine management light does'nt come on.
The MAF must be built into the throttle body then, a MAF is not mentioned in dialogys, just the MAP.
Specs for the air temp sensor according to dialogys are
-10c 10450 to 8625
25c 2065 to 2040
50c 815 to 805



I have removed the sensor and tested in the house, these are the reading's I got
1830 ohm at 32c
2190 ohm at 25c
2030 ohm at 26c
3680 ohm at 13c
18950 ohm at -14c
20000 ohm at -15
it's not exactly to Renault spec, would it have to be spot on ? according to dialogys it say's 2040 to 2060 at 25c
So to me it seem's to be working as the resistance is rising and falling as the temp alters, but as soon as I reconnect it the poor running come's back

I tested it with a multimeter (digital) and one of those laser temp guns
 
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