failed emissions 4.0, high CO

[a bum with money]

hi m8's!   :waving:

 

been dealing with this for 6 months now.        I have a 88 mj 2wd a/t, 4.0, big ton, 125k miles city mpg 16, 4000mi since last tune up

cap,roter,plugs, and wires

 

my most recent emissions test (oregon):  failed in the CO catagory. 1 is the std,  tested 4.9 (idle).  5.0 (2500rpm) non dyno.

hc 220 is the std,    tested 160,      CO+CO2     tested  10.6    (not sure what the CO+CO2 is).

 

these are the things I've tested so far.

 

all grounds-   good

egr valve-     good

egr sol.-       good

map sensor- good   5 volts in and out @sensor

mat  sensor- good   < 800 ohms warm)

cps  sensor- good   222 ohms

cts   sensor- good   (inline w/mat sensor)

o2 sensor-   good? tested w/ohms meter +/- 100, not infinity reading

feul injector resistance-  good    17.5 ohms/ all 6

tps sensor-  good  tested w/ohms meter,  .72 closed/ 4.75 wto.+/-

 

recently replaced vacuum tree (both sides) did fix some vacuum leaks,( but failed emissions after fix)

 

the truck starts right up and idles great! If anything it has a slight rough idle but not bad, and idle might fluctuate slightly.

all things I could live with.

 

still has the original injectors, and for all I know sensors too. I didn't want replace the injectors without good reason.

I also haven't checked anything on the ecu, uncharted territory!

 

would welcome any ideas ( or criticisms either) on others things like kick, spit on, hold tongue left or right      :???:  

 

Bryce

 

 

[mnkyboy]

Good old Oregon DEQ,one of my XJs was having problems passing. Even though the O2 seemed good i tossed a new one in it and it flew through DEQ with flying colors.

[a bum with money]

good ole Boring Oregon, not quite far enough away to escape deq, but far enough away to escape Portland.   :cheers:  

you know that is what I was thinking too, I read somewhere that the o2 sensor should be replaced at 82k +/-.

 

there not that expensive either about 60$ or so. any particular brand? there are several.

 

what about leaking injectors? how would you check?    :???:

 

any opinions on remanufactured injectors ?

 

anybody?

[johnj92131]

My guess is you want to install a new O2 sensor.  I had an Emissions issue last March, Don posted this about the 02 sensor:

 

"The NTK 23023 O2 sensor is the one you want - same as OEM but cheaper."

 

Amazon has it for about $37.   I have an new one to go in along with new exhaust manifold that I ordered from Amazon. 

[Marine1Texas]

High CO normally means running rich. With the renix if your pressure is to high this can be one factor causing more gas per squirt. yes a leaky injector could cause rich as well. the O2 sensor could also cause it to run rich

[a bum with money]

thanks for the input guys. were going to do the obvious first. o2 sensor it is. cheaper than new injectors..... for now.    :help:

[mnkyboy]

good ole Boring Oregon, not quite far enough away to escape deq, but far enough away to escape Portland.   :cheers: 

Hopefully closing on a house in Sandy at the end of the month,the address is outside of the DEQ boundaries so i will be free of emmisions testing.

[Marine1Texas]

here in Texas over 24 years old no emission testing. So hollowed out cat with EGR that is working but not hooked up to vacuum. Also with larger injectors and bore over throttle body. I like the renix my self it is very easy to find the problems... 

The other MJ is carbed 4.6 HEI with no computer and no need for emission!

[a bum with money]

I'll bet that on those 265 acres you have a very nice size shop too (very jealous),   as well as wide open country to run with open pipes!   :thumbsup:

 

would a exhaust leak in the exhaust man and/or pipe near the o2 sensor cause the ecu to misread the a/f ratio? I have a small exhaust leak under the hood somewhere. 

 

haven't checked it out yet, but was just curious.     :doh:  

[cruiser54]

I'll bet that on those 265 acres you have a very nice size shop too (very jealous),   as well as wide open country to run with open pipes!   :thumbsup:

 

would a exhaust leak in the exhaust man and/or pipe near the o2 sensor cause the ecu to misread the a/f ratio? I have a small exhaust leak under the hood somewhere. 

 

haven't checked it out yet, but was just curious.     :doh:  

What brand spark plugs are you using? Anything gimmicky?

 

Your O2 sensor test is not a good one to rely on.

 

Do the NTK O2 sensor. 

[a bum with money]

What brand spark plugs are you using? Anything gimmicky?

 

Your O2 sensor test is not a good one to rely on.

 

Do the NTK O2 sensor. 

 

 

I.m running ngk's  nice tan color no carbon/oil build-up

 

ordered ntk 23553 o2 sensor from rock auto.        47$ w/shipping   85$ local yikes!

 

my sense on this is to replace the o2 sensor and move on from there    :crossfingers:

 

 

thanks for the o2 sensor tip   :thumbsup:

 

Bryce

 

I will post the results as I narrow down the fix and addon to this thread just in case anyone else has the same or similar problems.

 

any thoughts on a leaky exhaust man./pipe near the o2 sensor causing a misread for the ecu on A/F ratio's? would that even be an issue?

[DirtyComanche]

Exhaust leaks are not likely to throw off the O2 sensor, as the pressure in the exhaust is normally higher than ambient (as in, the exhaust leaks out, not clean air leaks in).  Your header is probably cracked up in the back where a couple of the tubes join, they all do that over time.  If it's a really massive leak (one of the tubes has broken right off) it could possibly be affecting things though.

[cruiser54]

Exhaust leaks are not likely to throw off the O2 sensor, as the pressure in the exhaust is normally higher than ambient (as in, the exhaust leaks out, not clean air leaks in).  Your header is probably cracked up in the back where a couple of the tubes join, they all do that over time.  If it's a really massive leak (one of the tubes has broken right off) it could possibly be affecting things though.

Well stated, and true. 

[a bum with money]

we have crackage in the exhuast manifold!   :mad: climbed under jeep today with flashlight in tow and sure enough saw a hairline crack at the joint (near collector) back tube.

 

saw a lot of replacement headers online and a lot of opinions. and was wondering.... I plan on keeping this jeep for a while, was considering header

 

back to muffler replacement, didn't want to go top shelf, didn't want to go crap either, and  being this is a 2wd drive and a daily driver and stock condition.

 

what would be a good way to go.

 

 

I plan on doing the manifold work myself. can you get bolt on quality exhaust pipes,cat,muffler and what not?

 

thanx for the advice, been very helpful.    :bowdown:

 

bryce

[DirtyComanche]

Honest opinion.  It isn't worth it to go to an aftermarket header.  Just have the stock one welded.  Or buy one of those really cheap stock replacement ones that perform worse than the OEM part.  The problem with the Renix is that it uses its own header, as it has both an EGR and O2 bung in it, so the HO ones will not exactly work.  If you can delete your EGR (not sure if that's really an option for you, since you have emissions testing) and go to a HO header and downpipe/midpipe, it opens up a lot of options for aftermarket exhaust.  Otherwise you're pretty much stuck with Walker replacement stuff, or having it made, or making it yourself.

 

There is some power to be gained by going to a good aftermarket header, but I don't feel it's great bang for the buck, and many of them are troublesome to fit and have the same cracking issues as the OEM part.  Also, some of the HO aftermarket headers will not clear the Renix intake manifold, and some will not even clear the early HO intake manifold.  I run into more trouble than I wanted when I bought a cheap Amazon stainless HO header and bolted it onto my Renix engine, wound up having to convert to a HO intake plus do some custom clearancing.

 

I wound up building my entire exhaust system using a couple sections of 2.5" straight pipe and some J-bends that I bought from Summit, since I wanted stainless and the local shop quoted me $1000 for materials alone. (I think it was under $100 for all the material from Summit, with leftovers).

[a bum with money]

Honest opinion.  It isn't worth it to go to an aftermarket header.  Just have the stock one welded.  Or buy one of those really cheap stock replacement ones that perform worse than the OEM part.  The problem with the Renix is that it uses its own header, as it has both an EGR and O2 bung in it, so the HO ones will not exactly work.  If you can delete your EGR (not sure if that's really an option for you, since you have emissions testing) and go to a HO header and downpipe/midpipe, it opens up a lot of options for aftermarket exhaust.  Otherwise you're pretty much stuck with Walker replacement stuff, or having it made, or making it yourself.

 

There is some power to be gained by going to a good aftermarket header, but I don't feel it's great bang for the buck, and many of them are troublesome to fit and have the same cracking issues as the OEM part.  Also, some of the HO aftermarket headers will not clear the Renix intake manifold, and some will not even clear the early HO intake manifold.  I run into more trouble than I wanted when I bought a cheap Amazon stainless HO header and bolted it onto my Renix engine, wound up having to convert to a HO intake plus do some custom clearancing.

 

I wound up building my entire exhaust system using a couple sections of 2.5" straight pipe and some J-bends that I bought from Summit, since I wanted stainless and the local shop quoted me $1000 for materials alone. (I think it was under $100 for all the material from Summit, with leftovers).

 

I like that idea. :Canadaflag:  didn't think that was a viable option, assuming the metal is thick enough still. after looking at the crack again you might be able to add a gusset

 

between 5&6 pipe and another gusset under to stiffen it up.   :smart:

 

the flex section I've seen pic's of, is that something that is welded in (flange,etc) or just cut out a section of pipe and add a couple of hd hose clamps? :dunno: 

 

 

bryce

[Eagle]

would a exhaust leak in the exhaust man and/or pipe near the o2 sensor cause the ecu to misread the a/f ratio? I have a small exhaust leak under the hood somewhere. 

 

 

Yes, it would.

[DirtyComanche]

Normally you can just weld them up without doing anything special, the metal is plenty thick.

 

Most of the flex pipe stuff is meant to be welded in, but some can/should be clamped.  It depends on the style.

[johnj92131]

Hole in my manifold caused me to fail emissions. Fixed hole, test passed. Hole came back on recent cross country trip, check engine light came on, truck ran like crap. Cleared code and truck ran better. Cost me 4 mpg on that tank.

[a bum with money]

I will get the new o2 sensor in a couple days and will go ahead and install it. and if I fail again I just might get some jb weld and do a temporary fix just to get thru DEQ

 

(going to be a b*@$£ getting up in there!)  :crossfingers:

 

I have already started the hunt for a good used renix ex manifold, and may just get a set of reman. injectors since I have the manifolds off.  700,710, or 746's.

 

really appreciate the advice so far, A big thanx to the comanche club members!   :clapping:

 

Bryce

[a bum with money]

hi m8's!   :waving:

 

been dealing with this for 6 months now.        I have a 88 mj 2wd a/t, 4.0, big ton, 125k miles city mpg 16, 4000mi since last tune up

cap,roter,plugs, and wires

 

my most recent emissions test (oregon):  failed in the CO catagory. 1 is the std,  tested 4.9 (idle).  5.0 (2500rpm) non dyno.

hc 220 is the std,    tested 160,      CO+CO2     tested  10.6    (not sure what the CO+CO2 is).

 

these are the things I've tested so far.

 

all grounds-   good

egr valve-     good

egr sol.-       good

map sensor- good   5 volts in and out @sensor

mat  sensor- good   < 800 ohms warm)

cps  sensor- good   222 ohms

cts   sensor- good   (inline w/mat sensor)

o2 sensor-   good? tested w/ohms meter +/- 100, not infinity reading

feul injector resistance-  good    17.5 ohms/ all 6

tps sensor-  good  tested w/ohms meter,  .72 closed/ 4.75 wto.+/-

 

recently replaced vacuum tree (both sides) did fix some vacuum leaks,( but failed emissions after fix)

 

the truck starts right up and idles great! If anything it has a slight rough idle but not bad, and idle might fluctuate slightly.

all things I could live with.

 

still has the original injectors, and for all I know sensors too. I didn't want replace the injectors without good reason.

I also haven't checked anything on the ecu, uncharted territory!

 

would welcome any ideas ( or criticisms either) on others things like kick, spit on, hold tongue left or right      :???:  

 

Bryce

 

the above post is where I started, today I installed a new o2 sensor (less than 5 min.) and headed down to DEQ to do an emissions test ( 5th time!)

 

and passed!   :banana:    I went from a HC 160 to 21 and a CO of 5.0 to .05!

 

first I want to thank everyone here for the expert advice on possible fixes.and the  methods of approaching the problem.  :bowdown:

 

since I had did the last tune-up, I knew that that was not the problem, next I checked the vacuum lines and found that the small plastic lines were old and brittle

 

as it turned out there were small leaks. replaced all the vacuum assy. 60$ (both halves)  and checked all other vacuum lines as well. no more leaks.

 

then and only then! did I starte to doing the sensor checks as perscribed in cruisers54 renix tips  http://www.cruiser54.com/ 

 

it only took me about an hour to check all the checks I did in my original post. after all that, then I replaced the o2 sensor #ntk 23553 at rockauto.com 47$ shipped

 

not only did I not waste time and money, I also learned a little more about the renix jeep for it!

 

I can't say it enough, DO CRUISER54's TIPS FIRST!!!!!! you will be a better jeep owner.

 

here's to the helpfull members of this club!   :cheers:  :cheers:  :cheers:

 

bryce

[cruiser54]

Thanks for the update!! 

 

And mostly, glad to hear you passed. Is the idle better?

 

Exhaust manifold still cracked? 

[a bum with money]

much smoother! just topped off the tank to see what the mileage will be. tomorrow morning will be a cold start, but I know it will be turn key   :crossfingers:

 

yea, still will have to deal with the small crack in the ex man. It just so happens my neighbor has a 89 mj, and makes frequent trips to the local yards. I think I'll tag along!

 

this really puts my mind at ease, now I can focus on some other more minor issues to deal with, oil adapter upgrade HO, brakes shoes, front stabilizer bushings,

 

p/brake you know, the usual stuff.

 

thanks for the tips! was very helpful.

 

reading the forum posts  really takes a lot of the mystery out of taking on the bigger jobs.  :brows:

 

bryce

[cruiser54]

much smoother! just topped off the tank to see what the mileage will be. tomorrow morning will be a cold start, but I know it will be turn key   :crossfingers:

 

yea, still will have to deal with the small crack in the ex man. It just so happens my neighbor has a 89 mj, and makes frequent trips to the local yards. I think I'll tag along!

 

this really puts my mind at ease, now I can focus on some other more minor issues to deal with, oil adapter upgrade HO, brakes shoes, front stabilizer bushings,

 

p/brake you know, the usual stuff.

 

thanks for the tips! was very helpful.

 

reading the forum posts  really takes a lot of the mystery out of taking on the bigger jobs.  :brows:

 

bryce

I'm not a big believer in cracked exhaust manifolds causing a Renix to fail emissions. 

 

Any manifold you find will be cracked. They can be welded successfully by competent folks and last a long time. 

[a bum with money]

that makes a lot of sense, being that the pressure inside the manifold is greater than outside.

 

that neighbor I mentioned also has a wire welder too, I've seen some of his work on a xj project he's been working on, not bad.  mmmmmmm.........

 

bryce