89 YJ failed emissions please help

[Gerr]

I picked up a 89 yj (carburated)6cyl 5 speed runs great and wheels even better, but at the test only emissions station it got flagged as a gross polluter here are the numbers

rpm 780
%co2 7.1
%o2 8.9
HC MAX 120
HC measured 2000
co% Max 1.00
co% measured 2.23

rpm 2431
%co2 10.5
%o2 4.8
HC MAX 180
HC measured 1367
co% Max 1.00
co% measured .28

It also failed on the EGR function test as well because it doesnt open up so Im replacing it, It had the OEM O2 sensor so I replaced that and Ive run a full seafoam treatment in her now. I leaned out the mix a hair(1/4 turn) on the carb per the testing mechanic's suggestion.

Anyone have any suggestions? Ive read tons on here about this abd I feel im on the right track ust wanna make sure im not forgetting something

[90xj06]

i failed on NOx. that little black thingy before the egr does not work or the solinoid. it is alittle confusing reading the numbers can you seperate them by lines

yours max
" "
so on

[Gerr]

thre ya go fixed it

[90xj06]

i think both of those are catalytic converter things. what for some one to approve that theory.

[old_man]

First things first. Pull a spark plug and tell us what the color of the insulator is. Your HC is way high. That can be from running way too rich or burning oil. The spark plug test will tell you a lot.

Also do a vacuum reading at an idle. If the cat is plugged, the reading will be way low.

Have someone watch your tailpipe as you take off. Too rich will give you a black smoke, burning oil will give you a more blue haze. With your readings, you should definately need see some type of smoke.

[Gerr]

Ok pulled 2 plugs they both look the same:
some black residue on one side. (light and easy to remove not oily) redish grey on the other.

it hasnt been driven since I leaned it the carb and the new o2 sensor but it did idle for about a hour while i checked for exhaust leaks and vacume leaks.

It shows no oily residue or sighns of oil burning it has a bad leak in the rear main but what heep doesnt

[silverslk]

Ok pulled 2 plugs they both look the same:
some black residue on one side. (light and easy to remove not oily) redish grey on the other.

it hasnt been driven since I leaned it the carb and the new o2 sensor but it did idle for about a hour while i checked for exhaust leaks and vacume leaks.

It shows no oily residue or sighns of oil burning it has a bad leak in the rear main but what heep doesnt

Well first of all, does the O2 sensor even do anything since its a carb'd motor? I can't figure out how it would lean/richen the mixture??

Second, I on't know a lot about emissions but maybe check www.car-sound.com (http://www.car-sound.com) and go to the "converter basics" and also "efficiency charts" as the later helps show what causes what readings to be high or low.

GOOD LUCK!!!

[8Mud]

You got to set the low speed idle jet by the book and the sequence is somewhat complicated. Just twisting it a quarter of a turn, isn't gonna help much as the air controlers are gonna want to compensate.
If you can get a schematic (electrical and vacuum) of the sensor loop. you can try to troubleshoot the loop one stop at a time. A real can of worms.
One simple thing you can check is the *secondary* tube running from the manifold to the Cat (I forget the proper name). The hookup breaks often at the manifold.
I've found the carbed YJ's a whole lot more difficult than the Renix XJ.
WWW.off-road.com has some good stuff in the how to sections and the archives for the YJ.
The carburated emission control setup is tempermental to say the least.
I cured mine by bypassing most of the control circuits and replacing them with a simple Mopar ignition module changed the distributor to vacuum advance and disabling the air controllers. But I got lucky, the tester didn't know what he was looking at and didn't detect my mods.
Search YJ ignition at www.off-road.com , don't jump on the "Nutter" solution too quick, a lot of guys have screwed that one up.
Some guy did a write-up on swapping out the existing ignition control module with a Mopar unit and improved the original idea some. I went back and redid mine his way. Though not by any means a gauranteed fix, it worked out fine for me.
Yor best solution is to collect the proper reference material and try to fix what you have. The vacuum switches are tempermental and control most of the emission functions. The O2 feedback loop for the carburator air controllers is also a sore point. The cat and the plumbing for the Cat are also a sore points. The low speed and idle circuit in the Carb. gets gummed up and really messes with your idle. There are writeups on the fix for gummed up carb, a good one (I think) at www.Jeepz.com

[hideyoshi]

It sounds like it's definatley your CAT. If you know a nice smog tech you could have the him super-heat the Cat before the test. the super heated cat will burn up the bad gasses that are causing you to fail... just a suggesting.

[8Mud]

Well first of all, does the O2 sensor even do anything since its a carb'd motor? I can't figure out how it would lean/richen the mixture??

Second, I on't know a lot about emissions but maybe check www.car-sound.com (http://www.car-sound.com) and go to the "converter basics" and also "efficiency charts" as the later helps show what causes what readings to be high or low.

GOOD LUCK!!!

The carb system has a couple of air controllers under the carb, to richen and lean the mixture and also has an Engine control unit (or ICM), that has timing input.

http://jeep.off-road.com/jeep/article/articleDetail.jsp?id=277060&searchString=yj%20ignition

[JohnX]

Before you start replacing Cats and "superheating" them, you may want to fix the problem. I have never seen anything fail that bad on HC's unless it has a misfire. All it takes is one cylinder to mis during the test and the number will skyrocket.

BEFORE I GET FLAMED...I didn't say there aren't other possibilities, just that I have seen numerous cars fail with HC's in the 2-3000 range and it was always a misfire. Sometimes the misfire is caused by too rich, too lean, or Electrically.

[DaffyXJ]

Sell it and buy an XJ.. :heart:

[Gerr]

Sell it and buy an XJ.. :heart:
I already have 2 XJ's dont want a 3rd!

Im searching for a miss and cant find one John that was one of my first ideas as well. It may be just a slight one or random i guess but damn if i can find it

[SanDiegoXJ]

if its just a slight/random miss...have you checked the rotor/cap...if its starting to wear you may not be getting enough spark causing a random miss and consequently the high HC reading....just a thought

Michael

[Gerr]

Todays addition

cap and rotor are in good condition, wires are in spec resistance wise, pulled all plugs and they all look the same (redish grey one side darker on the other) installed the new egr and cleaned the ports. made sure all wires are clicked on well, timing seems ok, fixed exhuast leak in egr tube, had wife watch for smoke from the exhaust and thats a negative. Im really starting to suspect the cat or a misfire that i cant find. anyone else have any ideas, sugestions?

[8Mud]

Just like the XJ it has closed loop and open loop functions. If all the vacuum lines aren't hooked up, one of the sensors or switches is faulty or other things, it may stay in closed loop, which is typically rich.
Coolant temperature switch, thermal electric switch, low and high vacuum switches, oxygen sensor, WOT switch, closed throttle switch, knock sensor, mixture control solenoid, idle relay, up and dowstream solenoids and PVC solenoid.
Look down the carb, work the throttle and watch the air controller pistons work in and out. Just a physical type test, to tell you if they function at all.
I'm trying to think what would cause the high HC. The system stuck in closed loop. Vacuum leak causing the cylinders to burn unevenly, some lean, some rich (incomplete combustion), the O2 sensor just provides an average, metered by left over 02, if some cylinders are running rich you'll likely have unburnt carbons. Faulty O2 sensor, air controllers sticky, low compression, plugged/dirty air cleaner, PVC. I've seen many broken off knock sensors on the YJ, don't know exactly why. Oily connectors for the distributor/sensor assembly. The pulse air system would likely have more to do with high NOX.
EGR actually helps with more complete combustion, but only actually does much, at higher RPM's. If it is stuck open (even partially) at idle (makes for a really poor idle), it could also cause incomplete combustion. On the earlier EGR valves, mostly from my Dodge experiences, the seat gets crusty, there is even a reaming tool to clean the seat.
And lastly, I've flunked HC, becuase I let my truck idle a lot the day before the test. It flunked the first time through, but after a 10 mile run up the interstate it passed just fine. Some additives help with more complete combustion, which can help with HC.

[Gerr]

thanks mud ill look into those today

[Gerr]

found a blue vacume line disconnected it leads to the t-case and I cant find where the other end plugs in.

[90xj06]

its a vent line it does not go any where. do not connect it to a vacuum sorce.

[Gerr]

its blue with a check valve at the end there is a vent line that is black rubber 3 times the diameter of the blue hard plastic one you still think its a vent?

[90xj06]

the blue is vent for t-case. remember its vacuum controlled and its got to release its pressure somewhere. where does the black one go??? on my 90 i6 the only black one near there is cruise control.

[Gerr]

mine has 2 black ones one that is part odf the secondary yellow one to actuate the 4wd light switch and the other black one goes to the t-case.

The large black one i mentioned before is just a vent fot the t-case housing, looks exactly like the other 4 231's I have laying around for non vacume disco front axel setups

[90xj06]

well thank you for the info good to know.

[Gerr]

btt

[Gerr]

ok a update

To date Ive replaced/adjusted/fixed:
plugs
wires
cap
rotor
o2 sensor
egr valve
fixed 2 vacume leaks
leaned out carb 1/4 turn
seafoam treament both in tank and in carb 2 times now

Things Ill be doing soon
oil change
and getting a new cat

Im fairly sure the cat is not working, I bought a inferred tempreture gun and after running for 20 minutes around my yard (10 acres) the cat's temp was 15 degrees cooler than the pipe entering it and the pipe exiting was about 10 less than the cat so obviously its not burning anything. so I decided to make it run rich and see if it would heat up and after about 15 minutes of running rich the temps were lower than before but the 15 and 10 degree difernces were still there. so I do believe my cat has biten the big one.