eec egr scheme

[Jon]

Clive Apps Techno-Logicals 416 510 0020 wrote:
> 
> >
> > 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

I guess I didn't say up front that my system is MAP.  The five liter
from which I borrowed the system dumps the exhaust gas into the same
chamber that all the inlet air passes through, where temperature and
pressure are measured.  Because the EGR is more or less inert, we no
longer have 4:1 ratio by mass inert:oxygen, which is the basis for 15:1
"ideal" A/F. I think the controller will have to compensate for this.
But more important, does the controller even direct EGR to occur at WOT?
That's where I'll have to compensate for a five liter controller running
a 3.5 liter engine, since WOT is open loop.  TVR Jon