my jeep just failed emmisions. it is registerd as a 94 2.5L but acutally has a 98 TJ 4.0 in it. he did how ever test it as a 4.0. so I am guessing that was a 94 4.0 since he would have no idea what year it came from.

the part I fail on was the N0 - ppm. he said it was the EGR systems but I don't think either YJs or TJs have EGRs do they?

I am tryin go figure out why I failed. the cat is only 1 yr old but during the swap it did get really hot and could have melted the insides. I also have a 180 thermostat in it. some one said that would make a difference.

any ideas???

EGR....exhaust gas recirculation....all the Jeeps of the 90's have them....do you have an after-market header? Also, for emissions purposes you should have a 210 thermostat.

jeeps in the 1990's did not have egr's. unles they were the low output motors. which would have to of been a rare s.o.b.
you need to check it for carbon build up or a lean mixture. if both of the are good then your cat is probably bad. if you take the vehicle to a muffler shop they will usually test the cat for free.
if it has carbon build up then go to your local gm dealer and buy some top engine clean. if it is a lean mixture then you need to find out what sensor it fawkin up. good luck.