Runs too lean to pass smog in CA

[mycj7]

I have a 1984 Jeep CJ7 and it passed smog 1 year ago. I haven't been driving it much. The more I drive it the better it runs. I drove it the last several days in hopes of smog it to sell it. I took it in and it did not pass in CA. It was too lean. I probably should have driven it some more first. But I assume there is some carbon deposits. Any quick/cheap ways to get it to not run so lean and thus pass smog and run better???

 

[Torxhead]

Too lean is a new one on me. Anyway the first thing I would check would be the O2 sensor. This controls the fuel mixture by reading the exaust temp. There is a website on how the Ca. CJ emissions system works and I will try to get it for you.
Edit: here it is Jeep Adventures Under the Hood
The O2 sensor can be checked with a digitial volt meter as the sensor gives off between .1 and .9 volts, if the meter moves all over the place it is good.

 

[Fastatv]

^^^^^^^^^^^^^^^^

New one on me as well.... You could also richen the air/fuel screws maybe a 1/2 turn or so to richen up the idle mixture. Might only take a 1/4 turn.....just have to try it.

 

[Posi]

I didn't see that he ran FI so the O2 wouldn't apply. Most likey a dirty passage in the carb that needs a cleaning. Quick and easy, do as Fastatv said. Make sure you tell the potential new owner it needs a carb rebuild.

 

[jzak]

Hey Bud!
This maybe the last resort, but installing a Howell TBI kit should get you to pass SMOG. I read about some other CA Jeep owners who bought the TBI kit just to pass the smog test. It seemed to do the job for them.

I've got a Howell TBI on my CJ5 AMC 258 i6 / 4.2l , and while I haven't had to do a smog test, the fuel economy is excellent (18 mpg), and it doesn't smoke at all.

A TBI kit is very expensive, but if you've exhausted every possible fix, it maybe something to think about.

Good Luck!

 

[Posi]

I drove it the last several days in hopes of smog it to sell it. Any quick/cheap ways to get it to not run so lean and thus pass smog and run better???

I would say he isn't looking to install FI.

 

[jzak]

I would say he isn't looking to install FI.

Well, if he can't pass SMOG they way it is, his CJ is worthless in California.

 

[Posi]

The fuel adjustment screw should give him the results he is looking for, if it doesn't, it will cost him $25 for a carb rebuild kit. Could be a vacuum leak as well.

 

[Lumpy Grits]

Lean??
Look for vacuum leaks. Start with mak'n sure the manifold bolts are tight.
Then ck EVERY vacuum line and connection.
Bet you have a vacuum leak somedangplace.
Get a vacuum gauge and take a reading at idle? What does the gauge say and what's the altitude where you live?
What mods have you done lately?
LG

 

[Hedgehog]

Do you have duel exhausts? Lately I've had to tell the tester 3 out of 5 times that the CJ has Duel exhaust pipes. The guys would test and test, then I'd say, "did you notice that there are two exhaust pipes?" Oooops! Retest.

OR

Does your CJ have a leak somewhere in the exhaust system? Sucking in clean air will give a lean test result. Usually rejected.

 

[Lumpy Grits]

Those idle mix screws don't do much-The 'puter will override your adjustments.
OP-Is the a 'Ca. model' CJ??
LG

 

[Fastatv]

Those idle mix screws don't do much-The 'puter will override your adjustments.
OP-Is the a 'Ca. model' CJ??
LG

Back when I had a carb business in VA, adjusting the air/fuel screws could make a vehicle pass or fail either way...all of the vehicles I adjusted had computors. Educate me here.....and others as well. Exactly why do you say that they don't do much?

 

[Lumpy Grits]

The stepper motor on the OEM Carter carb(what the OP should have on his Ca. model '84)overrides the manual idle mix adjustment, IF everything else is work'n 'rite'.
Idle Problems

LG

 

[Fastatv]

The stepper motor on the OEM Carter carb(what the OP should have on his Ca. model '84)overrides the manual idle mix adjustment, IF everything else is work'n 'rite'.
Idle Problems

LG

Guess I'll buy that..... Giving this some thought, tho my memory isn't the greatest, I don't really recall adjusting a Carter BBD to pass emmisions. Seems like they were mostly Ford and GM. Might still be worth a try tho....and maybe not......

 

[hagar]

You could have a bad upstream/downstream check valve that is pumping exhaust into the air cleaner. Pretty common with the pulse air system.
While idling, take the air cleaner lid off; if you hear excessive gurgling at one or both of the tubes where the rubber hoses attach at the base of the air cleaner, then one or both of the check valves are defective.
The easy way to tell is if it isn't idling very smooth, and you take the air cleaner lid off, the engine will smooth out right away; not always. but most of the time.