eec egr scheme

[Clive Apps Techno-Logicals 416 510 0020]

> 
> Hi James,
> > 
> > Uhmmmm john.  I don't know about fuel delivery but the main difference is
> > ignition timing.  When the ECU opens the EGR valve (and the EGR valve
> > position sensor confirms this) then ECU also advances the timing.  This
> > is to make up for the leaner mixture because lean mixtures burn slower
> 
> It seems to me that if you throw in more inert exhaust gas, and then
> don't compensate by putting in less fuel, the mix will be rich. If you
> ran the engine on pure oxygen (no nitrogen) and did not compensate by
> adding more fuel, the mix would be lean. What am I missing?

actually if you ran on pur oxygen it wouldn't be lean
the pistons, heads, gaskets and block would make up for the leanness

with added EGR it will be neither rich nor lean
the extra inert gas is not flowing through any of the metering system
that affects incoming air, it is rerouted internally in the block
so the A/F stays in sync
but the timing has to be advanced to let it burn properly

Clive