odb2 reading intake manifold pressure?

[makikulit]

Claymore, just a quick question i've been tinkering with this odb2 elm327 scanner and what catches my attention is the intake manifold pressure mine goes around 4-5psi idle to 15psi at hway driving are these good values? BTW I'm driving a GD1 Thanks again...

[claymore]

Really can't help with this one right now. I will try and research it tomorrow.

[claymore]

This was the only thing I could find it gives the correct values but you have to read the captions to find them.


photos work in IE but not Firefox

http://www.hondafitjazz.com/manual/A...031FAAT00.HTML

[makikulit]

hmmm i'll try that procedure next week, nevertheless i also ask my friends with scanners to perform the similar checks and looks like 3 of us got really close readings so i think my intake is ok.

thanks for your time Claymore...

[macbuddy]

Originally Posted by makikulit

Claymore, just a quick question i've been tinkering with this odb2 elm327 scanner and what catches my attention is the intake manifold pressure mine goes around 4-5psi idle to 15psi at hway driving are these good values? BTW I'm driving a GD1 Thanks again...

makikulit, I monitor my MAP on a Scangauge2. My unit typically reads 5.7psi at idle, and also about 15 psi at freeway speeds. This would be about the right values for normally aspirated engines.
A tuner explained this to me about 2 months ago. IIRC, 14.7psi is one atmosphere. You would need forced injection in order to exceed 14.7 psi. For example, if you you were Turbocharged, and your gauge showed say 22.9 psi, then you would be running 8.2 lbs of boost.

22.9 psi -14.7 psi = 8.2 psi

If you are normally aspirated, then I am thinking that your gauge is rounding off to the next highest whole number, showing 15 psi rather than 14.7 psi. If you are force injected, then you are producing 0.3 lbs of boost.

[makikulit]

Thanks MacBuddy for the info, I'm just running stock :-) it's good to know that you verified our findings. Could this baseline 4-5psi be used to check if there are leaks in the system intake given that the car is at sea level?

[macbuddy]

Looking back at your original post, you state 4-5 lbs at idle. I told you that mine recorded 5.7 lbs at idle. I should add that my 5.7 lb value was taken while my 5AT was idling in gear. When I put the transmission into neutral, the psi drops to 4.5 lbs.