razor02097

run the injector cleaner then replace the O2 sensor. The cat may not be your problem.

cherokeesteve

First off replacing your cat will go a long way but it will not fix everything. CO's come from the fuel side and HC's come from the ignition side. High CO's will be from running to rich and high HC's will be from ignition timing or ignition miss, change your plugs, wires, cap and rotor and check the timing, and I would have an exhaust guy check your cat, he will put a inferred gun on it to check the temperature of the cat. A hotter cat will show that it is working to clean the exhaust a cool cat will either show not working, clogged or hollowed out.
Your EGR valve will show up as bad NOX or NO on your emission report you get, they should give you one and they are required to give you one.
Hope this helps.
Do not, I mean do not put alcohol in your tank could do more damage than help, and do not go down and have it tested with the injection cleaner in your tank, IT WILL FAIL, because of the cleaner will show up on the test.

cherokeesteve

After reading your smog report I see what your problem is, it is your EGR system, it either is not getting vacuum to open the valve or it has clogged passage in side the valve.
A good way to test your valve is with a vacuum pump, install the pump to the valve when it is not running and pump it up, "WE WLL PUMP YOU UP" sorry an old SNL skit, if the valve opens good, it may leak down if it is a back pressure style EGR, and if it is not a back pressure style valve it should not leak down, but enough technical talk. Install the pump while it is running and pump on it to open the valve if the engine stumbles or dies the valve is working and you may have a vacuum problem to the valve.
Again hope this helps.

xXWhiteXjJeepXx

so as far as the EGR system.. what should i replace to fix this? does it have anything to do with the evap canister?

razor02097

eh.... emission systems are greek to me

All I know is that the evap canister isn't a commonly replaced part. The EGR valve either works or it doesn't. I believe you can clean it. If it is really bad it should be replaced.


wish I could help further...

1987 new toy

No it has nothing to do with the evap system. When they did the test they hooked up a vacum to your fuel tank that tested your evap system if it passed and it should of if he ran the tests then your evap system is good.

xXWhiteXjJeepXx

thanks guys.. so how would i go about cleaning the egr valve?

cherokeesteve

Take the EGR valve off and look inside the egr valve and see if one of the passages is clogged and if so clean out that passage and check valve with vacuum pump and see if the egr opens then clean out passage that is clogged and install new gasket and egr valve.

cherokeesteve

Do what I said earlier and put a vaccum pump on the egr valve and while the car is running pump on the vacuum pump, if the car stumbles or dies the egr valve is working, and it may not be getting vacuum when it is running.

xXWhiteXjJeepXx

ok wen i put the vacuum pump on it the jeep doesnt die. it just runs with a little lower rpm and thats it. and i put a pressure gauge on it to check and wen i rev the motor it shows pressure but then it quickly drops back down to 0 and doesnt constantly stay open

cherokeesteve

There are 2 kind of valves for your jeep a back pressure and a non back pressure and one valve has a bleed down and the other does not so if the engine stumbles when you put vacuum to it, it sounds like it is working but if it only idles down a little then it may be clogged. Take the valve off look in both passages and see if there is a lot of carbon in one of the ports if so clean out with a pick and some carb cleaner until you have as much as possible out.
Install a new gasket and the EGR valve and re test with the vacuum pump, if it stumbles more than you know the passage is open working.
You may have a vacuum to the EGR valve problem, I think your jeep has a EGR soleniod that comes on to allow vacuum to the valve off idle.
Here is how you check it put a vacuum gauge on the EGR vacuum line and rev the engine up and watch the gauge if it starts to show vacuum then the vacuum part of the valve is working, if it does not show vacuum while revving the engine up then you have a vacuum problem.

xXWhiteXjJeepXx

as far a the vacuum porblem.. would running all new hoses fix the vacuum problem or is that something else? i havent got a chance to look at my NRG valve yet but im sure its dirty. i wanna try and clean it as best as i can so i dont have to spend $100+ on a new one. getting a new o2 sensor tomorrow since mine is 20 years old so hopefully thats helps alot

cherokee77

So did you get it to pass? If so what was the problem?
I am having the same problem.

AVjeeper

I just had the same problem on my 89 Cherokee, Nigh NOX over 1200.
I cleaned out the EGR Valve and the transducer. You can open the transducer very carefuly and clean with a toothbrush and soap. I changed the EGR vacuum solenoid because vacuum was not passing through. I put on a new Cat and I drilled a 1/16" hole after the muffler to suck in some clean air just before the smog probe.
My NOX reading went from over 1200 down to 1. All I could do was laugh in amazement. I spent over $400 on everything including the tests. I can't afford not to have registration.

Here is a great link to Jeep sensors.
http://www.lunghd.com/Tech_Articles/...iagnostics.htm

cherokee77

Right on thanks. I will give that a try.