omega0684
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| posted on 17/2/09 at 01:00 PM |
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map value of non running engine
im just reading through the MS manual again and it says
quote:
Connect your laptop to your MegaSquirt using a DB-9 cable, turn the ignition to run (do not start it), and verify that all the sensors give reasonable
values. The MAP should be about 100 kPa, the coolant and intake air temperatures should be approximately the same as the outside air, and the TPS
should read from 0 to 100% as you open the throttle.
is this right, the MAP sensor should read 100 kpa?
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britishtrident
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| posted on 17/2/09 at 01:03 PM |
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P Atmos
MAP = manifold absolute pressure
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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adithorp
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| posted on 17/2/09 at 01:06 PM |
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100kPa is about 1Bar so... yes.
adrian
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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mcerd1
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| posted on 17/2/09 at 01:12 PM |
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quote:
Originally posted by adithorp
100kPa is about 1Bar so... yes.
adrian
1bar is exactly 100kPa which is roughly 1 atmosphere
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omega0684
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| posted on 17/2/09 at 01:28 PM |
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so am i correct in saying that the faster you go the lower the kpa reading should get? im a little confused.
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vinny1275
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| posted on 17/2/09 at 01:37 PM |
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if you're using speed-density rather than alph-n, you'll find an ideal MAP - as you tune the engine the MAP will go lower and lower - then
you'll get to a point where whatever you do (fuel up / down, spark earlier / later), the MAP will go up again...
Did you get the msq last nite btw?
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MikeRJ
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| posted on 17/2/09 at 01:56 PM |
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quote:
Originally posted by omega0684
so am i correct in saying that the faster you go the lower the kpa reading should get? im a little confused.
No, if you think about it the maximum pressure you could possibly see in the manifold is atmospheric pressure i.e. 100kPa (unless you bolt a
supercharger on it!). You will only see this with the engine stopped or at WOT. With the throttle mostly closed, the engine is pulling a vacuum in
the manifold, so you see less than atmospheric pressure. i.e. the higher the manifold pressure, the greater the engine load (as long as it's
running).
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David Jenkins
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| posted on 17/2/09 at 02:05 PM |
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I got myself a headache the first time I had to think this through for Megajolt...
Engine stopped - MAP will be around 100kPa (atmospheric). Engine not sucking in air.
Engine ticking over, foot off throttle - MAP will be very low at around 20kPa (high vacuum). The engine will be trying to draw air in past the closed
butterflies.
Engine running fast, foot hard down - MAP will be approaching 100kPa (near atmospheric). The engine will be sucking in air, but the butterflies will
be open so very little restriction and no chance to build up a vacuum.
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omega0684
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| posted on 17/2/09 at 02:15 PM |
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CHEERS GARAFE MAN, that makes it easy to understand.
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David Jenkins
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| posted on 17/2/09 at 07:15 PM |
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