off car MAP sensor testing ?

[fenixus]

does anyone know of any method of testing MAP sensor off car ?

i followed SFI-53 instructions (FSM) for MAP testing and its power output seems flat no matter if it's open to atmosphere or i pull 20inHg vacuum on it.
testing was done on ECU pins (PIM and E2).

want to make sure this sensor is bad before i get a replacement for $250 just to find out problem was somewhere else (like a bad harness ground somewhere!) .

thanks.

[fenixus]

is there any way to do voltmeter testing on MAP sensor itself instead of ECU pins ?

MAP sensor's body has 3 pins. which ones would i need to measure to get the reading (if possible) ? i know it would be tricky, because the sensor needs a 5V power supply to work which won't happen if electrical connector is removed. *sigh*

I want to test sensor itself, because i do NOT trust wiring and computer in my car.

[Chris Crash]

What's the FSM say about it?

[fenixus]

http://www.camrystuff.com/manuals/Gen4/SFI.pdf
page 53.

here is a set of gen4 camry (97-99) FSMs:
http://www.camrystuff.com/index.php?page=Gen4_Manuals

00-01 require some more, because ECU and some wiring got changed in gen4.5

harness provides a steady 4.99V power to the sensor, not a problem here.

then i followed testing the sensor's power output under different scenarios (atmosphere, and vacuum pump pressure segments of 4, 8, 12, 16 and 20inHg). i had to test its output on ECU pins (PIM & E2), but all the time it was giving me a steady 4.22V which is like a joke, neither fits the atmospheric reading nor any vacuum segment (maybe between 4 & 8inHg would give this voltage) i tested it in with.

Since i completely do NOT trust ECU and wiring harness in my car (have my own doubts), i need to figure out how to test it semi-connected to harness (so it only gets power from it) and read the signal pin straight on sensor (once energized).

it seems that 4.22V falls into a low vacuum range reading, so it might be cheating ECU horribly if that's a constant (ECU may think the car is under hard acceleration all the time, at least with IGN ON engine OFF):

Output voltages between 3.0 and 4.5 volts indicate a low vacuum (high pressure) situation such as hard acceleration or a mechanical failure.

http://autorepair.about.com/cs/troub...042603a_06.htm

and also based on this, the atmospheric reading should be around 4.5-5.0V (mine was 4.22V !?)

Read the voltage or rpm. With 0 inches of Mercury (in-Hg) vacuum, you should get between 4.5 and 5 volts, or between 300 and 320 rpm.

http://www.ehow.com/how_4478865_trou...ap-sensor.html

here is some more on topic of how MAP works:
http://www.aa1car.com/library/map_sensors.htm

[Chris Crash]

Find the pin in the connector that supplies power, and use an alligator clip to wherever on the sensor it needs the power. And there you go.

[fenixus]

yeah that was my plan haha. pin and alligator clip. just need to confirm which one it is.

when i was testing power in connector i probed 2 edge pins in the connector, don't remember which one was hot, FSM describes it though, seems doable.

just not sure if i should read sensor's power output using both positive/signal and ground on sensor body or just positive/signal on sensor and ground on chassis.

[Chris Crash]

I think ground on chassis since it's not connected...does that make sense?

[fenixus]

i don't know haha! will probably try both, hope it won't hurt anything. will try tomorrow after work.

[fenixus]

hey Chris, does your part out include a MAP sensor ? could you do me a favor (if you have it for sale) and check the part number of that MAP in donor car ?

mine is 89420-06040, if you have same one i may be willing to try out once mine fails the testing (will know more tomorrow).

[Chris Crash]

I don't have the car itself anymore, but may have the MAP sensor. If the map sensor belongs on the engine, then I'm using it. If it doesnt, however, then I should have it.

Got a pic of it? Maybe on the car too?

[fenixus]

it's a small black box with red sticker on top of it, it's attached to firewall right below the windshield (center of vehicle) and connects to the back of intake manifold with a vacuum hose.

here is a diagram of 5s-fe vacuum piping (partial, around intake manifold), the red arrow points to MAP



don't have a real pic handy.

[Chris Crash]

Then I should have it! I'll sort through my boxes of hundreds of parts in a little bit for you and let you know!

[fenixus]

cool, take your time, no rush, i've been driving with this thing (supposedly) stuck for months, it won't hurt much i guess to do a few more days/weeks hehe.

i will post again once i confirm my MAP is bad (or not). PM me with part number and price when you find it.

[Rattlin_Steele]

Originally Posted by fenixus

it's a small black box with red sticker on top of it

IIRC, Chris was parting out a 1997. If so, the MAPS will likely have a blue sticker, part # 89420-06060. Should interchange.

Pic below is the one off my 97 where the mechanic broke the hose stem.

[fenixus]

Originally Posted by Rattlin_Steele

IIRC, Chris was parting out a 1997. If so, the MAPS will likely have a blue sticker, part # 89420-06060. Should interchange.

Pic below is the one off my 97 where the mechanic broke the hose stem.

thanks for info!

not sure now if i should get it.... hmmmm .... idk, i'd rather go with recommended OEM part for my year.
it's such a crucial component for ECU (and EGR on gen4) that i don't want to risk any even slightest incompatibilities... i guess i will have to visit a local junk yard when i need it ... $250 (MSRP $330) for new one is waaaay overpriced IMO....

unless the only difference is the bracket, then i may think about it.