Altitude compensation (Re: 286 Vindication)

Mark Boxsell mrb at mpx.com.au
Thu Feb 22 09:59:33 GMT 1996


At 01:48 PM 20/02/96 -0800, you wrote:
>
>> That's what people do however you have to stop the engine and restart it
>> at the top of the mountain before it corrects!
>> Two sensors is the best method. Two absolute or one absolute and one
>> differential is does not matter. (If you want to change altitude).
>
>Isn't it true that for a speed density efi system with an _absolute_ MAP 
>sensor, then altitude compensation is not needed?  For example, if you 
>changed altitude, the barometric pressure changes, which changes the 
>pressure in the manifold, which the MAP sensor directly measures. 
> Temperature (air density) compensation is still needed.
>
>Now for a efi system using the "trap door" air flow meter, I believe 
>altitude compensation is needed.  In addition to temperature  compensation.
>
>Bryan Zublin
>bzublin at gi.com
>

Bryan,
           Fair enough question. The map signal is used to index the Fuel/Ve
table so in order to index this correctly you need to know the barometric
pressure.
                
                        regards,
                                       Mark Boxsell
                                       MRB Design.




More information about the Diy_efi mailing list