Chevyguy358

iTrader: (4)

My map reads 3 volts when scanned with a snapon scanner. Normally they are supose to be around 1-1.5volts. I have tested it with 2 separate MAP sensors and the results are the same. The mechanic said that perhaps my cam isnt producing enough vacuum to properly opperate the sensor. My cam is making roughly 12 in. of vacuum at idle. Would that not be enough vacuum for the MAP sensor? What kind of vacuum should I expect? could there be anything else at fault for the 3 volt reading? I know many people are running larger cams than what I have just wondering if anyone else is having problems.

cam specs .510/.520 282/288 lsa110 +1.6rrs

jimmyblue

iTrader: (11)

MAP output is proportional to manifold pressure, opposite to
vacuum. Full scale is ~5V at 100kPa (0 vacuum) and near
zero at 30" or so. (30"-12")/30" is 60% of full scale, 0.6 x 5V
is your 3V reading right on the nose.

Forget "normal", this is the twilight mod-'em-up zone.

Chevyguy358

iTrader: (4)

I'm sorry I guess I dont fully follow....so is a 3 volt output within that cam's profile parameter in accordance to vacuum...the readings are right around 2.8volts or so...thanks in advance

edcmat-l1

iTrader: (10)

Yes.
Key on engine off, no vacuum, 100 Kpa=5 volts. Instead of getting fixated on voltage, look at your Kpa or Map vac.
But to answer your question, yes, 3 volts @ 12 in. vacuum is right on.