I have given considerable attention to the EGR issue on cars since the first time I saw it in the early 70's. That was always the first SMOG part I disabled but it never seemed to make any difference.
I currently run a 460 FI that I overhauled in an 88 f350 work truck. I kept the EGR intact because for the life of me I can not sort out any type of gain from removing it EXCEPT possibly a HP increase due to allowing a full conbustion chamber of combustable gases instead of the inert gas introduced by the EGR system. Causing lower fuel economy in the process.
I know it sounds like a sacraledge but I see no reason for the EGR system not to increase fuel enconomy overall due to essentially reducing the size of the combution chamber of the engine, which also has to reduce HP at the same time but cooling off the exhaust temperature. Properly installed and operating I also would think that the EGR system is mixture neutral in an engine. Since mixture is % oxygen to % fuel adding an inert gas to the equation will not change the ratio.
That would also explain why all my EGR deleteing attempts over 40 years on various engines, made no perceiveable difference in engine operation.
Now if the EGR system is not metering properly, all bets are off as to the effect.
As to your "will it run leaner [I believe it would run richer but the EMS will compensate when sensed by the O2 sensor] without the EGR" based on my experience and rudementry engine knowledeg the answer is NO because the EGR is mixture neutral in my analysis.
I did once have a 76 buick with the buick 350 bought new as a grocery getter for the Family. I blocked off the EGR circuit at the 12,000 checkup, never and any engine issues on the car for the next 60,000 miles when we got rid of it.
This is my free opinion and that is probably what it is worth!!
oleman, if you say that's what its worth, then that is what it's worth.
And i'm not at all worried by the hippie smog police.. not where I live
I should have given a little more detail of the project.
97 F250HD 460 speed density EFI w/ K&N intake filter
Banks torquetube headers and stinger exhaust
I may also do a full emissions delete(cat, air pump, etc) along with EGR delete
I want this thing to run as smoothly as mechanically, and electrically possible, so that it lasts twice as long as it already has. I will probably be buying a moates quarterhorse or similar chip, and the software to customize it so the computer will not be as much of an issue to deal with.
What other problems could I expect from doing this?
Removing or disabling the EGR is a moot point with respect to engine operation, it will run no richer or leaner without it. However the system cannot be completely eliminated without setting at least one code since the computer not only looks for an EGR position sensor but also that the valve moves correctly when commanded to, so as a result the RJM device will not eliminate all codes associated with EGR. The system can be defeated by blocking the tube at both ends but the EGR valve and sensor must remain connected and functioning correctly to avaid getting codes.
The only way to completely eliminate it is to turn off EGR functionality inside the computer with a tuner, then all the components can be removed without issue.
FYI... TAB and TAD are not part of the EGR system.. that's the Thermactor(air injection) system, but to avoid codes with these they need to remain electrically connected and the associated vacuum lines completely removed or capped.