I have been arguing with my friend who owns a mustang GT and he keeps telling me not to remove my EGR valve because it will noticeably decrease gas mileage, but I have only heard that the EGR affects emissions and can cause a rough idle. Is this true? are we both right? Is this different for rotaries than it is for piston motors?

 

Yes a properly functioning EGR system can have minor fuel consumption benefits at light loads, because the diluted air/fuel mix needs a greater throttle opening to achieve the same power, resulting in lower pumping losses through the throttle. EGR doesn't operate at idle (because it causes poor idle quality) or high load (because it costs power).

The main reason it's there is to lower emissions, specifcally NOx. Because it's cut off at idle, it'll only cause idle problems if a component fails, like a broken vac line (common vac leak) or a split diaphram (causing EGR at idle).

IMO if it works leave it alone. If it doesn't, remove it. If you need to pass an emissions test, it'll need to be working properly.

 

to add on to his great explaination, NOx is created at high temperatures and the recycling of the gas allows the engine to run at a lower temp, thus preventing the formation of NOx and increased engine temp. Some states don't test for NOx when smoging so if you live in one of those states be my guest and take it off if you want...

 

well, emissions aren't a problem for me where i live (chicago just exempt all pre '95 cars w00t!)
so I was going to remove the valve when I pull my engine to rebuild it, mostly to prevent future problems and to clear up more space in the engine bay. I will however leave it on if the only side effect of a properly working egr valve is increased gas mileage.

 

Not meaning to contradict the emissions advice, but I've had NO problems with NOX and I removed mine looooong ago.

If the diaphram in the EGR fails, jsut make the EGR itself a blockoff plate. Get a piece of roofing flashing and cut the outline of the EGR on it and install it b/t the EGR and the intermediate housing. Done. No leakage will happen with a piece of 0.030 in between the EGR and the intermediate housing.

I'll post NOX to prove the above if challanged.

 

rotaries never needed an EGR valve, it was only installed because the retards who mandate emissions said 'you need to have it on there or we won't let you sell these cars'.

rotary engines already recycle a small % of exhaust gasses, my car passes even strict california emissions with damn near 0 NOx even after i run the **** out of it to get the cat smoking hot for the test and i have no functional EGR valve. at least on the FDs they got smart and put in a restrictor gasket, kind of defeating the purpose of an EGR valve anyways but if they gotta have it may as well make it the least amount functional as possible.

 

ok, so basically it has no purpose at all for the FC, and removing it will NOT significantly decrease gas mileage, or even emissions. yay! no more egr valve for me!

 

If its worth anything, s5's didn't even have EGR vavles.

 

umm, yeah they did. I removed the EGR valve off of my 90 GTU. And about the gas mileage thing, you drive an RX7. End of discussion.

 

Series five NEVER had a EGR valve.

Disagree??? Show me the page in the FSM or the Series five parts fische that shows a series five EGR.

Let's say you did have a EGR on YOUR engine. Then it ain't a series five engine. You've been HAD.

 

removed mine..doesnt seem much of a difference at all

 

I thought it was on the back of the LIM?

 

It was, on Series 4. I thought Hailers made that pretty clear...

 

jspec never had EGR either...