EGR Removal/Disable in relation to gas milage.
- Thread starter PANDA
- Start date
The EGR if removed will cause a decrease in gas milage. It purpose is to slip in inert exhaust gasses to cool the head temps during cruising when running at the A/F stoic ratio (14.7:1). They do this to reduce NOx emissions that occur during hotter head temperatures from the leaner A/F ratio. It is only active during mid-throttle cruising. If you remove it you will run slightly hotter due to higher head temps. The atomized fuel vaporizes sooner as it enters the hotter cylinder head reducing it effectiveness. (You want the fuel atomized in the cylinder and then to vaporize as it compresses for the most efficient burn/power.) The O2 sensor sees this as less fuel so it richens up the mixture and you use more fuel. If it did not richen up the mixture, The head temps would get too hot and lead to other problems.
Did you re-program the PCM for no egr? You also need to change the timing advace curve slightly to compensate for the change.
Some engines don't have an actual EGR valve, But rather an EGR passage between the intake and the heads. If I recall some (or all? ) of the LS series engines have this.
Engines built without EGR's do not run the cruising A/F at 14.7:1
Did you re-program the PCM for no egr? You also need to change the timing advace curve slightly to compensate for the change.
Some engines don't have an actual EGR valve, But rather an EGR passage between the intake and the heads. If I recall some (or all? ) of the LS series engines have this.
Engines built without EGR's do not run the cruising A/F at 14.7:1
Nope. I got them sealed up pretty good, but something happened and now they leak like terribly. I need someone that knows how to fix them. I think the place I went to to try and fix them fucked me good.
To contribute, when James turned off the EGR stuff in the PCM I know I lost 1-2 mpg.
Just put back in my GM O2 and gained 1-2mpg over the Delphi
PCM is tuned for no EGR, timing is also adjusted.
The timing needs to be retarded slightly due to the lean A/F ratio and no EGR.
Does the KR lessen with premium gas? If you are already using premium then the timing curve is still slightly too advanced. If you don't care about gas mileage some adjust the fuel curve at part throttle to richen it up a bit. The thing is not all engines of the same run the same. So you may need to retard the timing another degree or so at that point to prevent the KR.
In Panada's case if he isn't getting any KR, It could be that the timing curve could be a little too retarded. So he gets no KR, But burns a little more fuel or they richened up the fuel slightly. The thing to do is to monitor BLM, O2 and KR to see how it was set-up and what you can do to tune it back in. Advacing the timing slightly until you start to get some KR then back off a degree should bring the tune in better and increase your mileage.
Just out of curiosity, Why is everyone deleting the EGR? It doesn't affect power because it only works at part-throttle cruise. The rumor that removing it for more power is false. That only works on pre-1982 vehicles.
panada
I had to add additional timing everywhere. I started with a modified 05 timing table tommygloves had.
I just did mods and had the egr removed.
My mileage dropped 2 to 3 miles to the gallon.
I drive 140 Rt everyday and I log all of my miles and fuel. have for the last 4 years
I have 5000 on this setup below
My Mods
ZZP Stage 3 IC
Ported GEN 3
Fuel rails with 42 Lb Inj
1.9 Rockers
ZZP Headers with Custom catless 3in to SLP (EGR removed)
N* with Custom 4in K&N
3.2 pulley
10.4 ZZP wires with 104,s
ZZP PCM with custom tune
My mileage dropped 2 to 3 miles to the gallon.
I drive 140 Rt everyday and I log all of my miles and fuel. have for the last 4 years
I have 5000 on this setup below
My Mods
ZZP Stage 3 IC
Ported GEN 3
Fuel rails with 42 Lb Inj
1.9 Rockers
ZZP Headers with Custom catless 3in to SLP (EGR removed)
N* with Custom 4in K&N
3.2 pulley
10.4 ZZP wires with 104,s
ZZP PCM with custom tune
Last edited:
Ah, Yes I can understand that.
I know that many with the older GM 60 degree V-6's do it because the EGR is mounted on the crossover and a tube goes to the intake plenum. Problem is with normal road vibration on the crossover pipe the EGR tube cracks causing a leaks. Also once they swap out the stock exhaust manifolds for headers, The EGR port goes away.
It is probably due to the torque convertor still in lockup. It is normal.
There is a hidden spark modifier table for this condition based on mg/cyl vs RPM. You can pull some timing to compensate.
What is your OSID?
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