The sensor measures the changes in pressure (MAP=Mass Air Pressure) in the intake manifold and adjusts the amount of fuel injected accordingly
High pressure = low vacuum = WIde Open throttle
Low pressure = high vacuum = Closed throttle
Throttle plate partially open + high vacuum = engine under load
etc
It is essential for adjusting the fuel mixture and timing
Well, the emission test didn't failed but is really poor.
We tried to disconnect the sensor few seconds during the test and emission went better... I think It may add too many fuel in the mixture adjustment.
The guy at the emission test told me he has already seen that before with another kind of car and the replacement of such sensor had resolved the problem.
The car has been checked by Toyota very recently for some parts replacement and engine check (among other little things). They didn't find unusual things.
Yeah I think toyota calls it a vacuum sensor or something like that...
I the non toyota world it is called a MAP (manifold absolute pressure). If you call it a vacuum sensor most people will not have a clue what your talking about.
How many Km's do you have?
When was the last tune-up?
-spark plugs
- cap and rotor
- wires
- air filter
- fuel filter (not so much for emissions more for performance)
- timing checked/addjusted (since you have a dizzy)
When was the last time the oxygen sensor changed? (can cause poor emissions if worn out, and yes they do wear out over time)
I would start with the basics first.
Honestly, I don't know if I would trust that mechanic. It sounds like hes out to make a quick buck off you.
Well, it's my father-in-law who took care of the car until i bought it to him last week.
Check was done last month. I didn't have picked invoices up yet from him so I don't know the full history but I'm at least sure about filters, oil service, timing belt, water pump and spark plugs for the last tune up.
The rav4 has around 180000 kms.
The MAP sensor replacement advice doesn't come from a mechanic (well in fact he was, right before its current job), I know him very well and he's now in charge of a several technical inspection centers (every two years in france for cars that are at least 4 years old). In France, Car repair shops and technical inspection centers are two seperate things to avoid conflicts of interest.
During low speed emission test, he disconnected the MAP sensor, and emissons had reduced dramatically to more than a standard level.
May it be significant?
Beside this emission problem, the engine seems to work perfectly at low speed, and high speed, and I haven't encountered any acceleration problems.
I'll check the history of the vehicle, as soon as I get all the invoices.
I would suspect the map sensor disconnect just masked another problem.
If it was bad, i think the rav would run poorly.
Try driving with it disconnected, it will likely run very poorly.
plugs, wires, oxy sensors, I would suspect other things before the map sensor.