Well guys my 88 jeep cherokee failed the California emissions a few weeks back, and I'm gonna test it again this Wednesday or Thursday. I'd like to get any advice or help on what I should do. So far I've done a complete tune up minus the 02 sensor. Its got a oil change, new plugs, wires, cap & rotor, was seafoamed twice, also got a new fuel filter.
I passed HC and failed CO & NO. I think NO is nox, but don't know what CO is.

My results for the previous test are as followed:
15mph (1408rpm)
HC: Limit 87, actual 77
CO: Limit .75, actual 0.47
NOx: Limit 714, actual 901

25mph (2294rpm)
HC: Limit 73, actual 51
CO: Limit .95, actual 1.67
NOx: Limit 616, actual 739

I don't understand this and its my first time testing. I'm trying to figure out what else I should do before I go test. I plan to get a new 02 sensor before I test and was wondering if I should replace the cat? Or check anything else under the hood or anything? Just need advice!

EDIT: Not sure if this matters but I'll post it up anyway.
15mph (1408rpm)
%C02 14.3
%02 0.2

25mph (2294)
%C02 13.5
%02 0.1

 

I have a strong-ish exhaust smell at idle, or after I drive and let off the gas. I'm so stuck and don't know what to do.

 

CO is carbon monoxide, man.

How much of a gearhead are you? Do you have a set of wrenches, and a screwdriver and bit set? You can clean up your throttle body and idle air control, along with the intake temp sensor on the manifold. New ccv elbows and grommets may help, along with cleaning up your injectors and other fuel components manually.

Get your cat nice and hot right before testing by getting your engine speed up on the freeway, and replace that O2 sensor also!

 

Alright since my exhausts already off the jeep I decided to pull it apart and see what the cat looks like. The cat still has all the honeycomb in it, looks a brown-ish white color, doesn't rattle at all. I pushed on it with a screw driver & its super stiff and doesn't move. From the cat to the header though, the piping is filled with a black crust and stinks but I'm sure its normal.
Idk what to do right now, I'd like to have the best chance possible to pass. I payed and did it once, so this will be my freebee one. If I fail I'll have to pay again
I'm thinking I should grab the neon 4 pintle injectors, as an upgrade mainly but maybe help me pass? Also gonna run her till the fuel lights on and then let it idle itself out of fuel. Then fill with fresh 87oct. Also install a new 02 sensor, reset the ecu and seafoam it again.
I'm also pulling the intake and exhaust manifold tomorrow so I can wrap my exhaust, check for cracks and also clean the EGR. I can also install a stock airbox if that'll help? Right now its a cheap CAI.

Please guys any advice is appreciated here.

 

Well as far as gear head, I'm 19 went to WYotech and didn't get a job after...whata surprise
I just rebuild my buddies Lexus IS300. He blew his motor after making 438whp on stock internals. Its a 2jz but a weaker version. I rebuilt his motor with JE .20 over pistons, eagle esp rods. Hand ported the head. Did alot to that thing and h es currently making 701whp through the motor I build, a HX40S and a V160 (supra 6speed) transmission. It took up my whole summer rebuilding the motor and installing the trans but its good to go now. Got payed 3500 bought the jeep and now here I am!

Anyway I have a full on snap on tool setup and a decent tool box. Its a big matco rolling one. I'm not new to cars or wrenching, but this is my first car that I've owned and registered. I used to pit for a few guys that do circle & dirt track racing at our local tracks, so I work good under pressure 7 can keep pace with the best of them..Know how to do just about everything and don't mind do anything at all lol. Chris Tooley actually won while I was his only pit crew person. I was proud of that!
I've been wrenching since I was like 12, started with my grandpa and carried on from there. Deffinetly not a new guy, just new to registering and smogging my car I guess.

 

Good to know, man. Good to see you're not a typical Californian, too, you should move to Idaho lol... Yeah, take off the tb, clean it up and the iac. Get that O2 sensor done and go with NTK BRAND ONLY DO NOT USE DENSO, BOSCH, OR ANY OTHER BRAND. NTK is what mopar uses as OEM.

 

I'm in the same boat with my 88 ,but but way more nox .check your EGR valve positive pressure port that activates the valve right before the EGR valve itself . Mine was plunged not letting the EGR valve open ,this alone lowered my nox 400 ppm on both speeds ,just not enough for mine to pass

 

A coupla tricks that got my 86 VW thru after failing.

Back the timing off 2-3 degrees
Toss in a pint or so of denatured alcohol on a low tank of fuel.

Get that cat hot before the test!

Good Luck

 

There are a couple of tricks to CA emissions. First, Sea Foam it. BUT DO NOT POUR IT DOWN THE INTAKE. Put in a 1/4 tank of gas and drive it almost empty. That is what the smog guys do. Then fill it with 91 octane. New O2 sensor and you should pass

 

Hey now, watch it CherokeeMan, some of us are big and have been known to come out of the woods! Back in 03 my 90 failed the first time. I put a new O2 on it, and changed the oil, then this time left the teck alone with it. This time it passed and I paid him. I can't say myself for sure what car he put the sensor in though.

 

also, i would change out the MAP sensor as well, they are known to fail in the RENIX models alot. seafoam in the oil and the fuel. i would do it with a half tank and a whole bottle, then put 4 oz. in the oil and change it after 50 or so miles. this will break up alot of the carbon deposits. ensure the EGR valve works (easy way is get the car hot, then look down next to the throttle body and rev the engine by hand. make sure the EGR valve opens and closes). with it being super black before the cat and rich smell at idle usually means bad O2 Sensor, after you change it from the stock one they tend to fail alot.