ODBII Scan Tool, and MAP voltage at 6.25

[Diesel Freak]

A guy I know has a OBDII scan tool (do not know the exact make) and we hooked it up to the truck. The MAP voltage was 6. 25v AT IDLE with my boost module hooked up!

I am still making 34 psi of boost at WOT..... I think the Scan tool was misreading something, or do I have a problem?

 

[Michael Hughes]

I have check 4 trucks with boost modules with my Snap-On scan tool and they all showed boost at idle. I would think this is to get the ECM to fuel more while building boost.

 

[Diesel Freak]

but at 6. 25 volts? I think there is a problem with the scan tool

 

[Michael Hughes]

How much boost does it say that is. If I remember right, the ones I checked was around 14 PSI at idle with the boost module installed.

 

[Diesel Freak]

someone correct me here, but I think the voltage to the MAP sensor is only 5 volts hence a problem with the scan tool

 

[Hale on wheels]

According to the voltage vs boost map I got off this site some time ago, 6. 25V would equate to about 75psi on the 2001 trucks if you extrapolate to 6. 25, (since the table I got stopped at 43. 5psi @ 4. 04V). And I was also under the assumption that the map sensor operated off 5V.

 

[Diesel Freak]

That is also what I was thinking. I think I will go tell the guy that his scantool is FUBARed