need emissions help [ failed again ]

[crazygn]

My 1990 jeep cherokee fail again for the 2nd time. I think i get one more chance then i have to dump like 400.00 in the thing that i dont really have.

Is there any thing that i should change or check. this is the part that failed again.

Oxides of Nitrogen NOx

state standards--- 3.0000 GPM

MY JEEP ------------ 6.0466 GPM


failed

some one help me, this sucks

thanks
kevin

[gofstbuick]

Start with simple things, timing (as I remember, some jeeps have a very specific timing procedure, with timing being checked at 1600rpms). Timing could very well be too far advance. Also check ignition system and compression. Carbon build up could cause increased compression, and raise NOx numbers. Is the fuel system up to snuff. A mixture that is too lean may cause a NOx problem. Make sure the EGR sytem is working correctly. Rest your finger underneath the EGR pintle and throttle the engine up. Does the EGR pintle move? it should. Then manually raise the EGR valve pintle and see if the engine stalls or stumbles (at idle). It should. How is the cooling system? Excessive engine temps may increase NOx. If all those things check, then the catalyst is the final piece of the puzzle.
That is about it in a nutshell for addressing NOx issues. You've got some checking to do. Let us know, or email me tomorrow.

[crazygn]

great this is more then i thought i would get , thanks this will really help out.

i'll check the timing after work also the other stuff. How about the o2 sensor.

i'll check and get back with you.


thanks again bud

[crazygn]

also my tps is not set right and i think its going bad, could this also cause this.

[Aztlanahauc]

Like gofstbuick said ....NOX is a result of high temperatures in the combustion chamber....

causes of nox could be..
1. cooling system
2. egr valve
3. timing
4. catalytic converter

[gofstbuick]

Originally posted by crazygn
great this is more then i thought i would get , thanks this will really help out.

i'll check the timing after work also the other stuff. How about the o2 sensor.
thanks again bud

I forgot, a slow or lazy O2 can cause a NOx problem, because it cannot maintain stoichiometry fast enough to allow the mixture to be rich enough to shut down NOx in the cat.

[Epitome]

Why am I thinking that NOX is catalytic converter related? Am I wrong?

[TurboJim]

If memory serves, the 4.0's dont use EGR, rather a 3 way cat. Take a look at your CO2 and O2 readings, if over 12% and 1% respectively, suspect a cat not using O2, which means its probably dead.

[denn454]

there is a little trick if all that doesn't work. its not the right thing to do, but it will get you past emissions.

drill a few small holes in the exhaust pipe where they cant' be easly seen. these will act as venturis sucking in fresh air diluting the mixture. when your done you can just put a screw in the hole.

its better to fix the problem, no sence in having a car polute the enviroment anymore than it has to.

[TurboJim]

Originally posted by denn454
drill a few small holes in the exhaust pipe where they cant' be easly seen. these will act as venturis sucking in fresh air diluting the mixture. when your done you can just put a screw in the hole.

Actually, that depends how bad the car is. You might dilute the CO2 too far and cause the machine to kick you out for exhaust leaks.

The real unorthodix way would to disable a fuel injector...but I didnt say that <grin>

[crazygn]

[[[[Make sure the EGR sytem is working correctly. Rest your finger underneath the EGR pintle and throttle the engine up. Does the EGR pintle move? it should. Then manually raise the EGR valve pintle and see if the engine stalls or stumbles (at idle). It should]]]]


ok guys i tried this but i dont see any pintle under it, there is the rod in the middle of it, i pulled it out and the motor died, but when i give it gas the rod does not move in or out[ egr open or close] , should it, also should i have vac to it at all times, i dont fell any to the top and not sure about the bottom line.

i only have 10 day to get this done or they take my jeep off the road, its my only every day car i have.