EGR valve for EEC controlled emissions info/ bad performance

[Samurai0]

According to my Haynes Automotive Computer Codes Techbook, my 5.0L 302cid Merc GM, Exhaust Gas Recirculation (EGR) valve - attached to the intake manifold - helps to reduce NOx emissions.

So, if your emissions is showing a leap in NOx, where there was none,
(I noticed this on my last inspection) your EGR valve may not be doing it's job. BUT that doesn't mean the $75 part is bad.
Seen here:
http://www.rockauto.com/ref/Motorcra...l?cx-1230a.gif

There are two categories of EGR valves: 'Ported vacuum' & 'backpressure'.
There are two types of 'backpressure' EGR valves: 'Positive Backpressure' & 'Negative Backpressure'.

For our EEC controlled engines, backpressure from the exhaust controls the diaphragm in the EGR valve (you can see the valve). The vacuum comes from a small green plastic hose connected to the EGR valve.

***So, reduced vacuum in the entire system, engine, and AOD transmission is affected. The NOx levels increase too. This is what the book says,
"Remember that anything that changes the pressure in the exhaust stream will disturb the calibration of the backpressure system. This includes glass-pack mufflers, headers or even a clogged catalytic converter."

So, my performance problems are connected to the dual glass-pack cherrybomb mufflers I installed a while ago, totally throwing the calibration out of whack. And my gas mileage sucks. [This, I did know about before, and now I am up the creek]

And this is why performance mufflers are only put on performance engines that inhale more air, and create more backpressure - off setting the problems mentioned above.

What are your opinions on this?

[fredjacksonsan]

Makes sense; Ford does seem to run their systems with everything in relation to everything else, and when a part goes down or gets changed then it's all affected.

Makes sense though that if the backpressure changed, the sensors and all would think something was amiss, try to compensate (in a 1986 pea-brained computer sort of way) and end up mucking it up.

Might it pay, with the cherry bombs, to put in a 1986 5.0 Mustang/Capri computer chip or some aftermarket upgrade? I dunno.....sounds like research is in order; I'll let you know if I find anything.

[Samurai0]

Well, what I forgot to put in above is that the Negative backpressure EGR valves are used in High Performance vehicles.

Unforunately, the Positive and Negative backpressure EGR valves are not interchangable.

What could work is to get one of those 75mm or 95mm bolt-on adapters, including a different upper intake manifold, to suck in more air for added backpressure. Hopefully ths would cause a bottleneck at the headers, raising the backpressure to normal limits.

But, my finances are not in line to make a $300-500 intake manifold mistake.

I'll keep on plugging away too.
Thanks.