1990 Pioneer 4x4 Posted March 25, 2009 Share Posted March 25, 2009 I have a 90 MJ and all the headers that are available fit 91+. The only difference is this EGR fitting is missing on the newer headers. I have been told I could run it without the EGR, but I wonder if it will make a difference. Also, Will I pass emissions without one? :dunno: Any feedback would be helpful. Link to comment Share on other sites More sharing options...
Geonovast Posted March 25, 2009 Share Posted March 25, 2009 I've heard they run better without the EGR, as for passing emissions, that I don't know. I know they did away with the EGR in 91, so it can't be that vital... Link to comment Share on other sites More sharing options...
summerinmaine Posted March 25, 2009 Share Posted March 25, 2009 :agree: BUT . . . here in Kalifornistan, passing the smog test means having all the original equipment (visual inspection) as well as the tailpipe sniffer emissions test. Don't know what it's like in your state, but I would check first. Link to comment Share on other sites More sharing options...
1990 Pioneer 4x4 Posted March 25, 2009 Author Share Posted March 25, 2009 :agree: BUT . . . here in Kalifornistan, passing the smog test means having all the original equipment (visual inspection) as well as the tailpipe sniffer emissions test. Don't know what it's like in your state, but I would check first. Is there anyone who lives in Washington that knows the answer...? Link to comment Share on other sites More sharing options...
rworks Posted March 25, 2009 Share Posted March 25, 2009 I've heard they run better without the EGR, as for passing emissions, that I don't know. I know they did away with the EGR in 91, so it can't be that vital... I have an '01 engine in my MJ and it most certainly has the EGR. Link to comment Share on other sites More sharing options...
Windowsrookie Posted March 25, 2009 Share Posted March 25, 2009 I've heard they run better without the EGR, as for passing emissions, that I don't know. I know they did away with the EGR in 91, so it can't be that vital... I have an '01 engine in my MJ and it most certainly has the EGR. Then it's not an '01 engine. No 4.0L used after 1990 had an EGR valve. Link to comment Share on other sites More sharing options...
wolfpackjeeper Posted March 25, 2009 Share Posted March 25, 2009 ^ what he said. It depends, They did some work on the ports causing just a touch of backflow in 1991 which let them lower emissions and get rid of the EGR. If it works well, then it will run fine. I have seen cars that had a huge difference with the EGR removed and ones that had no difference at all. Link to comment Share on other sites More sharing options...
88XJSport Posted March 25, 2009 Share Posted March 25, 2009 Then it's not an '01 engine. No 4.0L used after 1990 had an EGR valve. Hell the 01 engine didnt even have a distributor!! Link to comment Share on other sites More sharing options...
terrawombat Posted March 25, 2009 Share Posted March 25, 2009 I have a 90 MJ and all the headers that are available fit 91+. The only difference is this EGR fitting is missing on the newer headers. I have been told I could run it without the EGR, but I wonder if it will make a difference. Also, Will I pass emissions without one? :dunno: Any feedback would be helpful. Both of my MJs have the EGR installed on the exhaust manifold, but the vacuum line on the diaphram before the EGR has been removed and capped. I was having a ton of problems with the trucks stalling as soon as you stepped on the gas and it turned out to be the EGR valve not functioning properly. They are expensive to purchase and they have been found to have little effect on the emissions of most engines. I've completely removed my EGR from my 3000GT and pass emissions with flying colors. It's intended purpose is to reduce nitrides of oxygen (NOx) emissions, so you'll likely see an increase in those, but not enough to fail you. Basically, the EPA and DEP catch wind of such devices that will theoretically lower emissions and they get an instant hard-on and amend laws/permits to include the installation of said devices. It usually takes several years (sometimes decades) to convince them that these devices don't do what they were intended and are more of a hassle than they're worth. I see it all the time in the field I currently work in... Oh, and to answer your initial question in the thread title, EGR stands for Exhaust Gas Recirculation. The valve will take exhaust gases and put them into the intake to dilute the stream with an inert gas, which will lower the flame temperature required for combustion and also reduce the amount of excess oxygen. Nitrides of oxygen form quicker at high temperatures, so lowering the temperature required for combustion is said to reduce their creation. Link to comment Share on other sites More sharing options...
Blue XJ Posted March 25, 2009 Share Posted March 25, 2009 When I built my stroker motor I removed the EGR system, I have had no adverse affects. Seems to run fine and gets better mileage than I did with the old motor. Link to comment Share on other sites More sharing options...
dakal Posted March 26, 2009 Share Posted March 26, 2009 :agree: :agree: :agree: :agree: :agree: :agree: :agree: Link to comment Share on other sites More sharing options...
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