alpine.adrenaline

In terms of isolating a problematic EGR, most of them have an open underside and you should be able to push the diaphragm up without a vacuum. That way you can determine wheter it is a plugged EGR port or if the EGR isn't actuating. If the engine stumbles a bit, the EGR is good and it's lacking sufficient vacuum. If not, the exhaust ports are clogged. In most cases the EGR can be removed and the soot can be cleaned out with a dental pick and some brake cleaner.

fantic238

The only function of a EGR is to reduce NOx emissions by reducing combustion temperatures.
As an immediate consequence the lambda factor is lower, the fuel/air mix is richer and the fuel consumption higher.
Since the ECU is able to correct the mix it will decrease the injection time and bring the fuel/air ratio back to 14.7
In the end you will have less NOx emissions, lower combustion temperatures, little more fuel cosumption, less power and more carbon deposits in the intake.

If you eliminate EGR you will have non cycling air/fuel ratio (good), more NOx emissions (bad), higher combustion temperatures (good and bad), less fuel consumption (good), more power (good) and less carbon deposits(good).

Savage6300

So assuming one installed a methanol set up, you would actually have to eliminate the egr? If the right air mass is achieved without adding carbon, and that’s what the ecu reads to determine this, then if it’s not reading enough carbon in the exhaust, would it still cause the egr to open up and dump exhaust into the air intake? Also, would a cat really be necessary if the right emissions are achieved without egr gasses? Because if we’re using methanol which breaks down into CO2 and water, there wouldn’t be the excess carbon that a cat “burns up.” So if we eliminated the cat, could that solve some of the potential condensation problems by increasing the velocity of the exhaust gasses? At least making the (cheaper) muffler the point at which you’d get rust. Learning a lot from this post. Thanks guys.

fb97xj1

I dont deal with methanol, but for those looking for the EGR on thier 91-01 4.0L XJ, they dont have an EGR. Ive read threads elsewhere that say the same for the 2.5, but i never looked into it.