EGR with speed density

[pman92]

Just a quick question I've somehow thought about.
On a vehicle with EGR and no MAF sensor, how would fuel be properly calculated to allow for the EGR flow?
I can't think of any vehicle that has EGR and is not MAF, do they even exist?
If it was solely speed density, the operation of the EGR would surely increase MAP and result in a rich condition due to the inert EGR gas and less O2 in the intake charge, unless there was some way to compensate?
Just something I've been thinking about and probably a bit off topic

[Dylan]

I don't have an answer but what do the LS1 PCM's do when they got to SD? May help with an answer. I've never done a LS loom where they've wanted the EGR wiring so tipping it's all disabled.

[MAGP]

I can't think of any vehicle that has EGR and is not MAF, do they even exist?

JD Camira

[Holden202T]

i know the way alot of the commodores charcoal canister purge is setup so it work on deceleration mostly or very high vacuum, so it really has no effect on normal fuel map areas, i dare say the EGR would be very much the same.

[vlt304]

us stuff has egr and map based the v8 chev tbi has an ecu controlled solenoid in the vac line to the egr not real sure how it all works I used the wires for air temp on a 12p conversion but I do have a read off the eprom out of the oem ecu and an xdf for it if you want to have a look. I just used the ve table out of the oem bin for a starting point to tune from with some expanding to fit 12p. unsure how good the rest of the xdf is.

[vlt304]

oops that bin was a downloaded bin this is the read from the eprom out of the oem ecu the xdf may need an offset of 2000 to match up

[Charlescrown]

Why don't you be a naughty boy and delete the EGR out of the equation. They cause so many problems and a good 3 way cat can do it all.

[vlad01]

i know the way alot of the commodores charcoal canister purge is setup so it work on deceleration mostly or very high vacuum, so it really has no effect on normal fuel map areas, i dare say the EGR would be very much the same.

EGR is used in conjunction with cruise areas to reduce NOx and improve economy which I think the mechanism is via reduced pumping losses. ie allowing the engine to breath more, less vac without actually making it go faster.

[vlt304]

i know the way alot of the commodores charcoal canister purge is setup so it work on deceleration mostly or very high vacuum, so it really has no effect on normal fuel map areas, i dare say the EGR would be very much the same.

EGR is used in conjunction with cruise areas to reduce NOx and improve economy which I think the mechanism is via reduced pumping losses. ie allowing the engine to breath more, less vac without actually making it go faster.

the emissions side of EGR is to displace surplus oxygen inside the combustion chamber to prevent the oxygen molecule bonding with the nitrogen molecule to form NOx. if you have nitrogen and oxygen inside an environment above 350 degrees c they will bond to form NOx. a byproduct of displacing the oxygen with exhaust is a cooler combustion environment. this is why modern diesel engines have either EGR or adblue to pass emissions tests.

[Charlescrown]

The egr simply lowers the peak combustion temperature. It's more like 1000 deg C where the oxygen and nitrogen combine. They only work under cruising and light throttle conditions so as to not reduce maximum performance. They are a pain in the proverbial with buildups of carbon deposits in the intake system. They do not enhance fuel economy but increase it due to wider throttle opening required to maintain the same speed. Adding extra fuel under these driving conditions does nothing but cause a richer mixture due to the inert exhaust gas going in. It's up to 20% at it's maximum. Just ask Volkswagen how good they are. Modern engines use VVT to do the same job without clogging up the valve and passages with carbon deposits.