MAP and TPS LOAD based EFI

Murphy, Ian Ian.Murphy at Arrows.com
Fri Jan 12 10:32:38 GMT 2001


'LOAD' is usually calculated using values for such parameters as volumetric
efficiency tables, manifold filling models, engine acceleration, even gear
ratios. For example LOAD would be greater if you're dragging a trailer up a
hill at 3000rpm 3rd gear WOT 100kPa MAP, than for passing through 3000rpm in
1st gear WOT 100kPa MAP as you leave the traffic lights.

A 3d RPM vs MAP table is just that - TPS or LOAD don't come into it, so
strictly speaking you can't use it to implement a LOAD based fuelling calc.
All you are doing is estimating an 'AIR CHARGE' value based on RPM and air
density, then looking up a fuel pulse width to get your desired AFR. The
true air charge depends primarily on inlet manifold dynamics and charge
temperature, with other secondary factors.

Mapping on a dyno / rolling road should get you 95% of the way there, and
you could try getting data on the volumetric efficiency of your engine if
you need to calculate some base values for your map.

Hope this helps...

Ian

> -----Original Message-----
> From:	Nicholas Parker [SMTP:nrparker at ihug.co.nz]
> Sent:	Friday, January 12, 2001 9:56 AM
> To:	diy_efi at diy-efi.org
> Subject:	MAP and TPS  LOAD based EFI
> 
> Hi,
>        How are TPS & MAP combined to form the 'LOAD" estimating variable
> in
> some EFI systems?   Does this techinque only apply to cars where the
> camshafts have overlap resulting in low vacuum (as in closer to
> atmospheric
> pressure than absolute vacuum!) at low engine speeds?  What is a good way
> of
> implementing this kind of control?  How do you implement this when you
> have
> a 3d RPM vs MAP table for you basic fuel 'calculation' ? Why would you
> want
> as well I guess!?
> 
> Cheers, Nick Parker.
> 
> --------------------------------------------------------------------------
> --
> To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the
> quotes)
> in the body of a message (not the subject) to majordomo at lists.diy-efi.org
----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org




More information about the Diy_efi mailing list