map sensor

[shooter mcgavan]

well fellas anyone know what this should read at idle and full throttle.i put diagnostics on the car other day and when i floored it,the value(in kpa)incresed.should it not decrease?hoping this is my low power and drinking petrol problem!

 

[Vtec6000]

It should increase when you floor it as your creating more vacuum. At idle if im correct you should read near enough to standard atmospheric pressure (101.325 kPa) or 18-21 inches of mercury.

 

[b16 mini]

It should increase when you floor it as your creating more vacuum. At idle if im correct you should read near enough to standard atmospheric pressure (101.325 kPa) or 18-21 inches of mercury.

thats not right, with the throttle wide open there will be less vacume,i think your confusing air velocity or volume of air being drawn with vacume.

vacume will be at its maximum when you floor it then shut the throttle off as the engine is effictivly sucking every last bit of air it can get.

example:
think about a hoover hose, put your hand over the end and the hose will try and suck it self flat! with a restriction the suction will be greater.

shooter, i'd think the value would increase but it would be in -kpa(vac) not +kpa(pressure)

 

[blinx9900]

Yes you have less vacuum at full throttle.

 

[Vtec6000]

Sorry my mistake, I should have said increase in negative pressure or as b16 mini has said -kpa

 

[shooter mcgavan]

yeah mine is not a minus figure,its 43kpa at idle and 96 when revd out.that cant be right!!thanks for replys keep them coming!!

 

[Vtec6000]

Have you a friend with a vtec that you can swap one off and try it on your car or just get the readings off his/hers to compare to

 

[b16 mini]

shooter, i'd think the value would increase but it would be in -kpa(vac) not +kpa(pressure)

sorry that should of said decrease, with more throttle the negitive pressure figure would reduce.

have you got/ can you borrow a vacume gauge, to see what is going on inside the inlet manifold,

the map sensor could be reading correctly, and the problem could be to do with your valves(inlet)

if you had incorrect cam timing, bent valves or sticking valves then its possible that its compressing the inlet manifold,

have seen ford zetec engines do this,(the early ones suffered sticky valves when using incorrect grade oil)

this would explain poor fuel consumption also, as the fpr would be shut at all times.

 

[shooter mcgavan]

well please god i dont have sticky valves!!i think ill swap one off a dc2 my mate has one will it work

 

[b16 mini]

it will fit,