Potential vacuum leak or faulty map?

[Torque Splitter]

Threw the Scanner on the RAV4 the other day to check for any pending codes stored. Fired it up and looked at the live data to make sure everything was going well. Everything was except my MAP sensor reading was only displaying 8.2 inHg. I had made a vacuum check via gauge on the intake a few months ago and it showed 14.5. I only thought this was strange due to no MAP sensor fault codes being present. Ideas?

[hd72m]

You may know but check this out.

The complete Solution for EGR system in RAV4 4-Door 4WD(3S-FE)

[Torque Splitter]

nah it has nothing to do with the egr being faulty, I am able to stall the motor by opening the port. the more i think about it, the more im leaning in the direction of the map sensor lying to the pcm.

[Pim]

Have you tested the voltage of the sensor and the ohms going through?
It may be faulty.

I am a bit surprised tough that you can take a gauge test at the intake on vacuum, while to my understanding no vacuum is build up at the (air) intake.
And are you sure it's not an air sensor or wide range air fuel sensor acting up because of being (very) dirty?
Have you cleaned the idle air control recently?
Have you used sea foam or anything in that sort to clean the inside of the engine?
Greetz

Pim

[Torque Splitter]

Originally Posted by Pim

Have you tested the voltage of the sensor and the ohms going through?
It may be faulty.

I am a bit surprised tough that you can take a gauge test at the intake on vacuum, while to my understanding no vacuum is build up at the (air) intake.
And are you sure it's not an air sensor or wide range air fuel sensor acting up because of being (very) dirty?
Have you cleaned the idle air control recently?
Have you used sea foam or anything in that sort to clean the inside of the engine?
Greetz

Pim

I plan on ohming it out tomorrow. Sorry I should have been more specific. When I said intake I mean plenum and not the ducting. I use a BG product called 44k intake and fuel system treatment. It's been about 20,000 miles since my last treatment so I should do one soon. The part that really trips me up is the lack of MAP sensor fault codes, I think another analog vacuum check should be done to make sure I don't have some sort of valvetrain issue.

[Torque Splitter]

hooray its the MAP! took a video of the test in case anyone would be interested in a DIY. The test showed about 16-17hg a little high due to the need of another treatment as well as an air filter change. Just happy with the steady needle =)

Vacuum check 99 Rav4 3SFE - YouTube

Vacuum check 99 Rav4 3SFE - YouTube

[Dr. Dyno]

You won't get a code because the sensor reading, altho wrong, is within the normal measurement range for the MAP sensor. A short or open will set a code.

[Torque Splitter]

good point, i just know Japanese cars are pretty sensitive with fuel trim codes. didnt know it had to be a complete short or open to trigger it. ty!

[Pim]

I was chuckling a bit, because you mention it to be the intake, while in fact you don't select the intake, but the vacuum system to be checked. The intake is below (the big black tube) which is a different system from the vacuum system.

And i am not following your reasoning for you to be so sure the map sensor is out of line here. But that may be me.
Greetz

Pim

[Dr. Dyno]

Originally Posted by Pim

And i am not following your reasoning for you to be so sure the map sensor is out of line here.

With the actual vacuum showing 16-17 on the analog gauge, the most likely faulty part is the MAP sensor since it gives a reading of 8.2 and also previously read 14.5.

OB detection systems for fault codes work by comparing the reading from a sensor to what it should be. Since in the case of vacuum the normal range is from very near 0 to 20+ any reading in that range has to be considered okay by the OB system since it has no other way to verify it's actually an error.