i already searched.

im having a map sensor code come up on a jdm b16.

the throttle body doesnt have a designated spot for the map sensor to plug into. i have it connected with a vaccum hose into the nipple of the throttle body.

i dont know why im getting a code. is it possible to check if a map sensor is working?

also would this not let vtec engage?

 

anyone?

 

also whats the diffrence between code 3 and code 5 ?

 

i'd have to look up the voltage in a manual, but yeah, you can check and see if its working with a volt meter. and in one of your other posts you asked if the cel would keep vtec from engaging. i'm not sure if those specific codes can, but i've always heard that certain cel would put your car in limp mode and would keep vtec from engaging.

 

MAP + RPM are use to lookup an initial fuel injector pulse width and ignition timing value.

So yes, if you're getting a MAP code, VTEC would not engage.

With the KOEO, the MAP should measure about 2.8-3.0v (atomspheric); with engine running pulling around 19-21" of vacuum, MAP output should be ~.95v.

Hell, you could use a vacuum pump on that rubber line, along with a voltmeter, and make direct measurements that way.

 

can you explain further how to check one with a multimeter please.

 

You put the red lead on the MAP output; You put the black lead on the MAP ground and then you turn yourself around - you do the Hokey Pokey.....

Turn the multimeter to a DC scale that is just higher than 5v.

It really is as simple as this....if you need further clarification, lemme know.

 

thanks. so im looking for :

MAP output should be ~.95v.

is that right ?
with engine idling?

also do you know the diffrence between code 3 and 5 ? they both say map sensor


sorry to ask, but which color wires are the input / ground.

 

Code 3: Defective cicuit or unplugged/defective sensor

Code 5: Mechanical problem/disconnected piping

Inside the ECU, there exists OSM's (output state monitor) - basically they look for current being drawn from a specific sensor. It would seem that with Code 3, the MAP sensor itself isn't even hooked up to the ECU. Code 5 seems to indicate that the MAP sensor IS plugged in, but its not changing values - kind like the hose connecting it to the manifold just isn't there.

The OSM part is true while those are my best guesses for what the codes actually mean.

Now, using your meter, and since I don't know what car this is, nor what wiring harness is being used, simply place the black lead on an engine ground and use the red lead to probe each of the three wires: You should record +5v (this is the reference voltage), the output (variable with vacuum/pressure) and the ground which should measure 0v, or very close to it. Of the three wires, the outter two are gonna be your +5v and ground with the middle being the output.

Why did I wait to give you that info - because if you guess which outter wire was the ground and placed the black lead on the +5v (with the red placed on the middel wire), you would get an incorrect reading.

And ASSuming your engine is pulling around 19-21" of vacuum, yes, the MAP output should be around .95v.

 

so i guess if im getting a code 3, i should check continuity between the harness and that specific plug?

its on a jdm b16, im not sure which harness its using, its obd1.

the map sensor isnt directly bolted onto the throttle body either. im using a piece of vaccum hose run to the nipple on the throttle body.

when im probing the wires, does it matter if the map sensor is plugged in? should i just start the car, unplug the map and then probe?

thanks for the reply btw.

 

make sure you have the correct nipple. there is 2 ports on the throttle body. one is small and near the thtottle cable and the other is larger and angles up above the throttle opening. make sure it is the one near the throttle cable. if you are unsure. tee it off your fuel pressure regulator nipple.

 

thanks to EE_Chris he helped me out alot earlier.

i checked the ground is good from the ecu that is good
im getting +5 volts from both outer sides of the 3 pin connector the middle ground.

i have continuity to all wires d17, d19, and d21 to the actual harness itself and map sensor.

the reading from the output i took from d17 and d21 im getting 5 volts instead of the 3 required.
why is this? is the map sensor bad?

with the car on and off its at 5 volts.