TBI MAP KOEO Vacuum value with ALDLdroid is -5.01

[Dezertracer]

I was expecting the vacuum to be 0 inHG without the engine running.

The stock 1989 K5 5.7l (L05) runs good, idles good and recently passed smog.
AFR runs 14.7 to 15.0 except under heavy load.
My concern isn't really the vacuum but the BLM is running about 108.

I replaced the MAP sensor but the KOEO vacuum value is still -5.01 inHG.
The 5 VDC reference to the MAP sensor is 5.023 VDC.
Idle vacuum is about 20 inHG.

Is the -5.01 inHG typical?
Is there another root cause for the low BLM besides possible exhaust leaks before the O2 sensor?
Thanks,

 

[Bent77]

That’s odd, especially after changing the MAP

 

[dyeager535]

Is the -5.01 inHG typical?
Is there another root cause for the low BLM besides possible exhaust leaks before the O2 sensor?
Thanks,

No experience with MAP unfortunately, but if it shows expected value at other times (cruise, idle, accelerating, deceleration) then I wouldn't worry about it. Especially if two act the same way.

Anything adding fuel could be the root cause, the low BLM is the ECM cutting back on how much fuel the engine is getting. Leaky injectors, wrong PROM, too high fuel pressure, vacuum leak(s), etc.

 

[Fastereddie]

I don’t know anything about tbi, but to me, it sounds like the sensor is showing - because with koeo it is seeing atmospheric pressure.