EGR temps
 

The EGR temp reading in EVOScan, is this something that can be valuable for tuning? I know it doesn't take the place of an EGT gauge but is the number totally useless?

I personally have seen my EGT temp reading drop during hard WOT driving, I just don't know if that number has any value...

I had the same question a while back. From what I can tell (and malibujack could explain to me) the EGR is basically just an emissions device. It's used to help determine when the engine has come up to temp. I don't think it will have any use for performance tuning.

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Well, its a useful indicator for the state of tune, but not accurate enough to use as a tuning aid.. I've watched the values enough to know, plus the EGR valve actually recirculates exhaust gas, when the valve is open the temps are different than when its closed so its hard to get a handle on what values are completely useful...

For instance, when you first start the car in open loop, the EGR temps are much higher than when the car warms up.. Not sure what value long-term that may be though..

Oh, and that temp is used to determine when the car should go into closed loop... the temps need to be high enough to "Light off" the catalytic converter.. Then when I see the car go into closed loop, the EGR temps drop, if you look at a log, their directly inversely proportional to the Coolant temp...