2000 4 Cyl 5SFE Map Sensor Behavior

[redekud]

I would like to hear from someone who "really" knows what they are talking about ... when testing the map sensor on this model car, should the voltage output go from hi to lo as vacuum is increased (or lo to hi)? I know what chilton/haynes says for this model, but what it says is the exact opposite of everything I find on map sensors on the internet. Thanks!

[hill8570]

According to the test procedure in the FSM (www.camrystuff.com , Generation 4, Diagnostics section, starting at page 29) the output of the MAP is larger at idle (large vacuum) than at 2500 rpm (low vacuum). I'd assume Toyota knows how their own sensor works.

[fenixus]

today i played with OBD2 software on my laptop (e.g. Digimoto) and noticed MAP sensor absolute pressure on my car to be ~25kPa at idle (~900rpm in Park) and dipping down the harder I pressed the gas pedal. i noticed it could dip down to ~13kPa when i revved it up to ~2000rpms but after holding it a while at such revs the pressure was going back up to ~25kPa.

according to all OBD2 software my car passes all ECM tests like EGR, fuel system, evap, oxygen sensor, engine missfire, etc.

[redekud]

I found a PDF from Toyota that had the exact same table as Haynes/Chilton but different wording. Toyota reads "voltage drop" and Haynes/Chilton reads "voltage". During my test, at zero vacuum, the signal wire voltage level was 3.55 volts. As I increased the vacuum, per the table, the "voltage drop" from the reference 3.55 volts increased exactly as the table indicated (which means the voltage went "down" as the vacuum increased). So, if you change the Haynes/Chilton wording from "voltage" to "voltage drop", and realize it is the drop from the zero vacuum reference voltage, it will then be correct:

0.3 to 0.5 voltage drop @ 3.9 in-Hg
0.7 to 0.9 voltage drop @ 7.8 in-Hg
1.1 to 1.3 voltage drop @ 11.8 in-Hg
1.5 to 1.7 voltage drop @ 15.75 in-Hg
1.9 to 2.1 voltage drop @ 19.7 in-Hg

To get the right voltage, just subtract the voltage drop at a given vacuum from the reference voltage at zero vacuum (3.55 volts in my case). My map sensor works perfectly!