1.6 16v MAP sensor voltage issue

[vijaycool]

Hi,
Today I back probed the map sensor wire with the digital multi meter. I am getting 4.98V on a 5V reference. The map output is 4.47V when the key in 'Mar' position. As the engine idles the voltage is 1.57V @ 800 rpm and 3k rpm its 1V.
Now the issue is when I switch on the AC button the output at idle changes to 1.96V and 3K rpm around 1.35V .I also checked the reference voltage with A/C there is no change still shows 4.98V. This eliminates Linear pressure switch issue. Now I am struck :bang: what causes the raise in MAP sensor voltage to 0.35V . Is this normal ? It will definitely affects the mileage. Please help.

Regards,
Vijay

 

[vijaycool]

Am I missing something. When the load increases MAP voltage increase.

 

[MrMigs08]

Maybe resistance changes as pressure changes, although voltage normally remains stable? :S Maybe i should pay more attention in electronics!

Is your car running ok?, could be pushing more voltage due to circumstance, if your idle and use electronics, you do tend to hear the revs shift slightly. (Maybe power too, more alternator juice!)