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KnoxButler 07-01-2013 11:25 AM

Emissions Results Help
Hey guys i finally built up the nerve to take my Jeep in to get emissions done...
Background: Bought the jeep (81 CJ7 258 w/ Carter BBD) from a guy who lived in an area that didn't require smog testing, but the jeep did have most of the smog system intact, EGR, etc. however none of it was connected up right. But I removed the exhaust he had on there (cherrybomb) that didn't suit my taste and replaced it with a new cat and muffler. I also did a team rush upgrade and rebuilt the carb using all the settings that came with the kit. I havent done anything with the EGR yet.
Problem: I didnt pass, that was to be expected, but now I need some interpretation and advice as to what I should do next. Here are my results:
HC=47 Standard=220 Pass
CO=0.05 Standard 1.20 Pass

HC=372 Standard=220 Fail
CO=4.54 Standard=1.20 Fail

My interpretation of this is that its actually really good. Under load it SAILED by! But while idling its not so hot. When I rebuilt the carb I set the two mixture screws in the front to 5 full turns out from seated. I never took the time to adjust it further than that to lean idle or whatever its called. I bet that would help out at least a little.
Any other advice would be awesome and greatly appreciated!

LumpyGrits 07-01-2013 11:53 AM

Your just wast'n time till you plug that EGR in.:thumbsup:

KnoxButler 07-01-2013 12:05 PM

I thought that the EGR only worked when the engine was at higher revs?


LumpyGrits 07-01-2013 12:23 PM

It's a BIG part of the whole package.
Again--You ain't ever gonna pass with out it!

KnoxButler 07-01-2013 12:25 PM

Do you think that that's all i need to get the co and hc levels down at idle to pass?


LumpyGrits 07-01-2013 12:33 PM

Well, that IS where you failed, correct?? :rolleyes:
AGAIN, I ask this-Do you have to pass a "visual check" for smog along with the engine test?

KnoxButler 07-01-2013 12:39 PM

I did pass the visual inspection, twice. I didnt pass because my idle emissions were to high.


LumpyGrits 07-01-2013 12:46 PM

And you have no chance of pass'n till you get the EGR going.
That EGR may NOT be all of it-------But, it's got to be work'n so you can go from there.

texas1al 07-01-2013 01:13 PM

As you mentioned, adjusting your idle mixture screws will help a lot with the idle reading. I would try leaning them out a little (turning them in). 5 turns out is a good starting point for my carb and a lot of other guys with the Carter, but try to adjust to lean best idle and then stay there instead if backing off the recommended 1/4 turn, or just back off 1/8 turn until you pass emissions. The factory setting for the idle mixture screws was closer to 1.5 turns out, but I hit lean best idle well before that coming in from 5 turns. You'll know you're making a difference just in the richness of the exhaust smell as you go. At 5 turns out, the exhaust fumes are probably so rich, it's burning your eyes.

LumpyGrits 07-01-2013 01:18 PM

It's a Carter BBD and the 'puter controls the fuel mix no matter how they are set.

texas1al 07-01-2013 01:25 PM

As I understand it, even with the BBD, the idle circuit in the carb is in part controlled by the metering screws. Maybe the stepper motor is involved as well and if it's functioning (not sure he's even got a computer on an 81, even the CA BBD's didn't make it onto the scene until 82 if I recall correctly), then at a minimum he should have the idle mixture screws dialed back to 1.5 turns per factory specs.

LumpyGrits 07-01-2013 02:03 PM

We don't know if it's the OEM set up or what the OP has messed with.
Some pictures and and engine # would help.

scrapman 07-01-2013 03:36 PM

Find a vacuum gauge and set your "best lean idle". You want to hook up the gauge to a manifold vacuum source, start with the mixture screws at 1 turn out, and turn both a quarter turn out at a time. Blip the throttle and read the gauge. the setting that gives you the highest vacuum reading should be the optimal setting.

Google "best lean idle" and you will find a lot better explanation. I set my idle this way, and it burns clean.

KnoxButler 07-02-2013 12:35 PM

Ok I was messing around with the mixture screws this morning and I turned them all the way in and started the engine... same manifold vacuum pressure as when they were 5 turns out.
Am i missing something? Could this have something to do with improper step up piston adjustment?


scrapman 07-02-2013 01:10 PM

2 Attachment(s)

Originally Posted by KnoxButler (Post 15632909)
Ok I was messing around with the mixture screws this morning and I turned them all the way in and started the engine... same manifold vacuum pressure as when they were 5 turns out.
Am i missing something? Could this have something to do with improper step up piston adjustment?


More to do with either improper low idle setting, or improper metering rod setting.

When idling, the throttle plates should be closed enough so that only the idle circuit it pulling gas though the carb. If your low idle setting has them open too much, the carb will pull gas though the transition circuit.

The metering rods could also need adjusting. The proper method for adjusting them can be found in the FSM. If you bottom out your mixture needles while idling, the engine should me dying, or trying to die.

These two pics are looking at the carb from two different sides, but hopefully you can make sense of them.

The time now is 05:24 PM.

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