2QUIK6

This is probably generic to any ECM, but I specifically am observing this on the $8D.
EGR becomes active once the MAT reaches a certain temp.
Now, where does the additional spark advance if any come from?
What I have observed is that for a given rpm/load, the spark advance that is in the main spark table for that combo is right on with what I see on my scan tool.
It appears that I have that same spark advance at that rpm/load combination no matter if the EGR is active or not.
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I've read bunchs of posts saying if you remove your EGR to be sure and disable it in the ECM by setting the Min. MAT for EGR active to 255, but given the above, your should also readjust your MAin Spark tables if getting any KR ??
Any thoughts?

2QUIK6

Anybody?
Or does using the EGR just allow you to put in more timing in the Main Spark tables and the EGR function itself doesn't effect actual timing whether its on or off?? If so, then it would make no difference if the EGR function is disabled or not as long as its disabled in the switch settings so it does not throw a code.

Grumpy

Nope, there is more going on the code then what the ALDL sends out. The only way to rule out anything not working is to disable a parameter so that it doesn't begin to work under some odd default setting.

No, the purpose of EGR isn't to allow you to run more timing, it's a matter of you have to run more timing with it applied to recover the HP lose of the hot air, and lack of O2 content.

I wouldn't try to over generalise too much, ie extend what happens in your particular car as being a universal truth. Unless you doing things from actually understanding the code. There is a big difference from just tuning, to understanding the code.

2QUIK6

Ahh, thanks Grumpy, thats what I was wondering since I was seeing no timing difference with the EGR either enabled or disabled by setting the Min MAT for EGR to function to x'FF', as I don't have an EGR, but am thinking about putting it back on, guess I'll wait and see if I can pass emissions next year without it.