"Bernd D. Ratsch" <bernd@dodgetrucks.org> wrote:
>> From: Phil Jenkins [mailto:bugnik@yahoo.com]
>
>> Ok, I hook up my scanner with engine off. I have 29"
>> of barometric pressure from MAP sensor. Start truck,
>> at idle I have about 11" showing on the scanner.
>> 29-11=18" of vacuum. I plug the exhaust and have 20"
>> on the scanner. 29-20=9" of vacuum. Less vacuum with
>> exhaust plugged, higher reading on scanner. Does that
>> sound right? (Pouring some gasoline on the fire.)
>>
>> Phil
>
> You have 11" manifold vacuum at idle or 11" MAP vacuum? 29" BARO is normal
> though. What is the 20" you're talking about?
Neither - the 11" he is referring to is a pressure reading (from
the MAP sensor), not vacuum. The 20" is the (pressure) reading after
he plugged the exhaust. All of the readings he gave are direct
pressure readings from the MAP sensor. Determining vacuum from the
MAP readings can only be done via calculation, which is why he
subtracts them from the barometric pressure to obtain the vacuum
values.
--
-Jon-
.- Jon Steiger -- jon@dakota-truck.net or jon@jonsteiger.com -.
| '96 Kolb Firefly, '96 Suzuki Intruder, Miscellaneous Mopars |
`-------------------------------- http://www.jonsteiger.com --'
This archive was generated by hypermail 2b29 : Tue Oct 02 2007 - 15:23:18 EDT