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MAP value oscillates
Posted: Sat Jun 17, 2006 12:31 am
by maztah
when the MAP value oscillates, does that mean there is vacuum leak?
Posted: Sat Jun 17, 2006 11:52 am
by Bernard Fife
when the MAP value oscillates, does that mean there is vacuum leak?
Not necessarily.
Lance.
MAP value oscillates
Posted: Sat Jun 17, 2006 9:44 pm
by ptegler
a fluctuating manifold vacuum can tell you a WHOLE LOT about the way your engine is running. (if you know what you're actually looking at. A Very good write up at ....
http://www.centuryperformance.com/vacuum.asp
Â
Paul Tegler
ptegler@cablespeed.com (
ptegler@cablespeed.com)
Posted by email.
Posted: Sun Jun 18, 2006 2:37 am
by maztah
i have a TBI setup. the MAP oscillates around 1 to 2 kpa especially during cold start.
Posted: Sun Jun 18, 2006 9:27 pm
by lmacneill
A cam with a high-lift or long-duration can also cause fluctuating MAP values...
My camshaft has 0.515" lift and 275-degrees duration on the intake, and 0.541" lift and 285-degrees duration on the exhaust. My MAP reading constantly (and seemingly randomly) fluctuates from 43 kPa to 50 kPa at idle... Smooths out just a little bit as the engine goes faster, but there's always a fluctuation of at least a couple kPa no matter what the engine speed.