'85 C7 258 - computer in the loop - stock everything
Damnit. I should have know better than to take my Jeep in for testing on a
rainy day but I did it anyway (it's a bit sluggish in wet weather). So here
are my results:

HC PPM Idle - 223/300 -- Pass
HC PPM 2500 RPM - 103/300 -- Pass
CO % idle - 2.10/2.00 -- fail
CO % 2500 RPM - 1.58/2.00 -- pass

I barely failed CO at idle -- seems all my idle readings are much higher by
ratio. I have been doing mostly city driving for a couple months. Would an
hour or so on the highway take care of the high CO? Any other hints? I
replaced the EGR and O2 sensor about 3000 miles ago.

 

Hi Kurt,
Yes, you should drive it so as to have it tested at full operating
temperature, you may need a new 195 degree thermostat to do that. You
may need a new catalytic convert, that's it's job to turn Carbon
Monoxide into harmless water:
http://auto.howstuffworks.com/catalytic-converter2.htm
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

KurtS wrote:
>
> '85 C7 258 - computer in the loop - stock everything
> Damnit. I should have know better than to take my Jeep in for testing on a
> rainy day but I did it anyway (it's a bit sluggish in wet weather). So here
> are my results:
>
> HC PPM Idle - 223/300 -- Pass
> HC PPM 2500 RPM - 103/300 -- Pass
> CO % idle - 2.10/2.00 -- fail
> CO % 2500 RPM - 1.58/2.00 -- pass
>
> I barely failed CO at idle -- seems all my idle readings are much higher by
> ratio. I have been doing mostly city driving for a couple months. Would an
> hour or so on the highway take care of the high CO? Any other hints? I
> replaced the EGR and O2 sensor about 3000 miles ago.

 

That sucks. I just replaced it two years ago.

> From: L.W.(ßill) ------ III <----------@***.net>
> Organization: Not@Home
> Newsgroups: rec.autos.makers.jeep+******
> Date: Mon, 04 Aug 2003 19:59:06 GMT
> Subject: Re: CJ7 barely failed emissions
>
> You
> may need a new catalytic convert, that's it's job to turn Carbon
> Monoxide into harmless water:

 

I have no cat and got 0.16% CO.

Am watching Dune, just in between episodes, will think on it.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

KurtS wrote:
>
> That sucks. I just replaced it two years ago.
>
> > From: L.W.(ßill) ------ III <----------@***.net>
> > Organization: Not@Home
> > Newsgroups: rec.autos.makers.jeep+******
> > Date: Mon, 04 Aug 2003 19:59:06 GMT
> > Subject: Re: CJ7 barely failed emissions
> >
> > You
> > may need a new catalytic convert, that's it's job to turn Carbon
> > Monoxide into harmless water:

 

High CO = too rich. Lean out the idle mixture a bit. You didn't fail by much,
so it shouldn't take a big adjustment.


In message <BB542759.1BE22%nospam@thanksImFull.spam>, "KurtS" wrote:

>'85 C7 258 - computer in the loop - stock everything
>Damnit. I should have know better than to take my Jeep in for testing on a
>rainy day but I did it anyway (it's a bit sluggish in wet weather). So here
>are my results:
>
>HC PPM Idle - 223/300 -- Pass
>HC PPM 2500 RPM - 103/300 -- Pass
>CO % idle - 2.10/2.00 -- fail
>CO % 2500 RPM - 1.58/2.00 -- pass
>
>I barely failed CO at idle -- seems all my idle readings are much higher by
>ratio. I have been doing mostly city driving for a couple months. Would an
>hour or so on the highway take care of the high CO? Any other hints? I
>replaced the EGR and O2 sensor about 3000 miles ago.

 

That's what I thought. It has been running a little rich lately (black tail
pipe recently). Since the canister is new from the dealer a few months ago,
I'll give the tubes a ream. It's been about 9 months since the last time.
Tnx guys!

> From: bllsht <nospam@invaliddot.net>
> Reply-To: nospam@invaliddot.net
> Newsgroups: rec.autos.makers.jeep+******
> Date: Tue, 05 Aug 2003 06:43:56 GMT
> Subject: Re: CJ7 barely failed emissions
>
> High CO = too rich. Lean out the idle mixture a bit. You didn't fail by
> much,
> so it shouldn't take a big adjustment.

 

In message <3F2FD37B.CE04B6CC@sympatico.ca>, "Mike Romain" wrote:

>Too rich can be caused from partially blocked idle tubes. The computer
>will set the stepper motor rich.

It doesn't work that way. The computer will correct the mixture (lean or rich)
to achieve the "proper" amount of O2 in the exhaust.

>
>See this link:
>
>http://www.off-road.com/jeep/tech/engine/carter.html
>
>A bad charcoal canister can also cause that, but with a bad canister,
>the idle will 'usually' surge up and down a little and you will get
>spits of oil coming into the air filter from the valve cover vent.
>
>Mike
>86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
>88 Cherokee 235 BFG AT's
>
>bllsht wrote:
>>
>> High CO = too rich. Lean out the idle mixture a bit. You didn't fail by much,
>> so it shouldn't take a big adjustment.
>>
>> In message <BB542759.1BE22%nospam@thanksImFull.spam>, "KurtS" wrote:
>>
>> >'85 C7 258 - computer in the loop - stock everything
>> >Damnit. I should have know better than to take my Jeep in for testing on a
>> >rainy day but I did it anyway (it's a bit sluggish in wet weather). So here
>> >are my results:
>> >
>> >HC PPM Idle - 223/300 -- Pass
>> >HC PPM 2500 RPM - 103/300 -- Pass
>> >CO % idle - 2.10/2.00 -- fail
>> >CO % 2500 RPM - 1.58/2.00 -- pass
>> >
>> >I barely failed CO at idle -- seems all my idle readings are much higher by
>> >ratio. I have been doing mostly city driving for a couple months. Would an
>> >hour or so on the highway take care of the high CO? Any other hints? I
>> >replaced the EGR and O2 sensor about 3000 miles ago.

 

In message <BB557AAA.1BF03%nospam@thanksImFull.spam>, "KurtS" wrote:

>That's what I thought. It has been running a little rich lately (black tail
>pipe recently). Since the canister is new from the dealer a few months ago,
>I'll give the tubes a ream. It's been about 9 months since the last time.
>Tnx guys!

Plugged idle tubes can cause it to run too lean(not enough fuel). Yours is too
rich(too much fuel). You could probably give each of the idle mixture screws
about 1/2 to 1 turn in (clockwise) and be fine. If the tubes are plugged,
cleaning them will only add more fuel. Not the direction you need to go.


>
>> From: bllsht <nospam@invaliddot.net>
>> Reply-To: nospam@invaliddot.net
>> Newsgroups: rec.autos.makers.jeep+******
>> Date: Tue, 05 Aug 2003 06:43:56 GMT
>> Subject: Re: CJ7 barely failed emissions
>>
>> High CO = too rich. Lean out the idle mixture a bit. You didn't fail by
>> much,
>> so it shouldn't take a big adjustment.

 

bllsht wrote:
>
> In message <BB557AAA.1BF03%nospam@thanksImFull.spam>, "KurtS" wrote:
>
> >That's what I thought. It has been running a little rich lately (black tail
> >pipe recently). Since the canister is new from the dealer a few months ago,
> >I'll give the tubes a ream. It's been about 9 months since the last time.
> >Tnx guys!
>
> Plugged idle tubes can cause it to run too lean(not enough fuel). Yours is too
> rich(too much fuel). You could probably give each of the idle mixture screws
> about 1/2 to 1 turn in (clockwise) and be fine. If the tubes are plugged,
> cleaning them will only add more fuel. Not the direction you need to go.
>
> >
> >> From: bllsht <nospam@invaliddot.net>
> >> Reply-To: nospam@invaliddot.net
> >> Newsgroups: rec.autos.makers.jeep+******
> >> Date: Tue, 05 Aug 2003 06:43:56 GMT
> >> Subject: Re: CJ7 barely failed emissions
> >>
> >> High CO = too rich. Lean out the idle mixture a bit. You didn't fail by
> >> much,
> >> so it shouldn't take a big adjustment.

Other way around bllsht.

The computer sees a lean condition because of blocked tubes and goes
into full rich mode.

When anything gets out of the computer's range, like blocked tubes will
do, it goes into 'limp home' mode and sets the carb rich and clamps down
on the timing advance.

The mix screws on a computer controlled Carter BBD are blocked by a 1/4"
deep and 1/4" round metal plug that has to be drilled or cut out to
adjust them.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

 

OOPS!

The one line should read:

Clean tubes and the 'idle' screw spring is about 5/8" long....

Mike

Mike Romain wrote:
>
> You are right, but blocked idle tubes can 'easily' make the mix go out
> of the computer controlled stepper motor's pins travel range.
>
> They adjust the air flow only, the mix screws are set at factory rich
> and plugged off.
>
> When the tubes really crap out, you have to remove the spring from the
> idle speed screw in order to get any idle at all. It goes out of
> range....
>
> When I see a carb with the idle speed screw compressed tight, I
> immediately suspect partially blocked idle tubes.
>
> Clean tubes and the mix screw spring is about 5/8" long, plugged tubes
> and the spring is compressed or about 3/8" long.
>
> If you can get at the mix screws, you can force the carb lean with
> them, That can pass emissions usually but doesn't address why it is
> running rich, just the symptoms.
>
> Mike
>
> bllsht wrote:
> >
> > In message <3F2FD37B.CE04B6CC@sympatico.ca>, "Mike Romain" wrote:
> >
> > >Too rich can be caused from partially blocked idle tubes. The computer
> > >will set the stepper motor rich.
> >
> > It doesn't work that way. The computer will correct the mixture (lean or rich)
> > to achieve the "proper" amount of O2 in the exhaust.
> >
> > >
> > >See this link:
> > >
> > >http://www.off-road.com/jeep/tech/engine/carter.html
> > >
> > >A bad charcoal canister can also cause that, but with a bad canister,
> > >the idle will 'usually' surge up and down a little and you will get
> > >spits of oil coming into the air filter from the valve cover vent.
> > >
> > >Mike
> > >86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > >88 Cherokee 235 BFG AT's
> > >
> > >bllsht wrote:
> > >>
> > >> High CO = too rich. Lean out the idle mixture a bit. You didn't fail by much,
> > >> so it shouldn't take a big adjustment.
> > >>
> > >> In message <BB542759.1BE22%nospam@thanksImFull.spam>, "KurtS" wrote:
> > >>
> > >> >'85 C7 258 - computer in the loop - stock everything
> > >> >Damnit. I should have know better than to take my Jeep in for testing on a
> > >> >rainy day but I did it anyway (it's a bit sluggish in wet weather). So here
> > >> >are my results:
> > >> >
> > >> >HC PPM Idle - 223/300 -- Pass
> > >> >HC PPM 2500 RPM - 103/300 -- Pass
> > >> >CO % idle - 2.10/2.00 -- fail
> > >> >CO % 2500 RPM - 1.58/2.00 -- pass
> > >> >
> > >> >I barely failed CO at idle -- seems all my idle readings are much higher by
> > >> >ratio. I have been doing mostly city driving for a couple months. Would an
> > >> >hour or so on the highway take care of the high CO? Any other hints? I
> > >> >replaced the EGR and O2 sensor about 3000 miles ago.