EGR

[jsmcortina]

What strategies would users like for EGR control?

James

[Kemp3]

clt , map and maybe tps but kinda redundant.

All thought how would it work in the Speed Density world ? in the MAF scenario less air is drawn by the motor with the "uncombustable" air from the EGR. I know when the EGR was open , MS would be aware but I dont know if a standard offset would work for all setups. Maybe and 8x8 table with subtractor from the main ve table ?

Or would EGO correction be able to deal with the difference ?

[Reverant]

You will need a table to tell the EGR how much to open (%) for several different RPM/load scenarios.

There different types of EGR valves (stepper motors, PWM valves), so one needs to account for this.

EGR must not be active during cranking.

EGR must not be active during idle.

EGR must not be active below aprox 65*C.

EGR must not be used with high IATs and high engine temps.

[jsmcortina]

I had a skim through Heywood last night and the description of EGR matches up with Reverent's comments. EGR is used to reduce NO formation, mainly during cruise by diluting the mixture and reducing the combustion temperature - while still running near stoich to keep the 3-way catalyst operational.

Linking in with MAF could indeed become tricky with up to 20% by volume EGR.

James

[jsmcortina]

I'd imagine that advance changes might be required with EGR too ?

James

[prof315]

I'd imagine that advance changes might be required with EGR too ?

James

Yes, I have seen OEMs run up to 50* advance at cruise with ECR flowing.

[prof315]

Some further thoughts, while in general stoich is the desired AFR target when running EGR, some OEMs use EGR in conjuction with "lean burn" economy mode. A small AFR target table ( 4 bins at most ) would be nice so that those of us a mpg junkies could try something similar. Same deal with timing though a simple adder/subtractor would probably work there.

[357supermagnum]

Any progress on the evap EGR valve controll ?

[MWPau]

Isn't EGR also used to lower pumping losses (hence increase efficiency) at low TPS values?
... just something to consider other than providing EGR control only for emissions use.

[hardline]

EGR also must be closed during overrun deceleration, otherwise it decreases engine braking.

[Pinchbit]

I found the following links to be informative.

http://www.autospeed.com/cms/article.html?&A=112729
http://www.autospeed.com/cms/article.html?&A=112730
http://www.autospeed.com/cms/article.html?&A=112612