[Diy_efi] About MAP sensing and it's jitter

[Tomas Sokorai Sch.]

Thanks!
I hope you're right, I have no scope, but I'll give a try to sample MAP in 
sync with the timing signal.
Right now the sensor reading loop runs async with the timing signal used in 
RPM and advance calculation (of course RPM & adv. are synchonous with the 
timing signal....it's supposed to (soon) be a ignition ;) . 
I'll graph both datalogs and post the results when I have them.
I have now the graphs from 2 datalogs from my home<->office trips with the 
async reading loop, if anybody wants to take a look of what they look 
like :) .

On Monday 12 January 2004 21:18, dunvegan wrote:
> Think about what you're measuring:
> you're measuring the volume of air that is being pumped by 8 different
> pumps sequentially, any difference between them like different valve
> sealing, plenum/intake friction/length, port restrictions, etc. can all
> cause differences between each stroke of the 'BIG' pump, so I would expect
> some jumping at idle.
>
> You should see the signal smooth out at higher rpm's, time/averaging taking
> place, I'd take a look on an oscilliscope sync'd to plug wire # 1 to look
> and see if there is a relationship to the jumping to a cylinder, if there
> is not relationship, then you may have a wear/jerky valve train problem,
> but I suspect you'll see it sync up and show it is the difference from one
> cylinder to another!
>
> Good luck, let us know what you see
>

-- 
Tomas J. Sokorai Sch.
Socio director, Gerente Proyectos Especiales
Xperts Ltda. F: 63 244591, Valdivia, Chile
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