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Old September 2nd 06, 07:23 AM posted to rec.autos.makers.jeep+willys
bllsht[_1_]
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Posts: 21
Default 89 YJ failed smog!

In message . com>, "Stevil"
wrote:

>Hello All,
>
>My 89 4.2L YJ just failed its smog on HC, results as follows...
>
>15mph MAX 124 AVG 34 MEASURE 125
>25mph MAX 104 AVG 23 MEASURE 104
>
>As you can see it was a real close one, it was well below average on CO
>and NO.
>
>I should have put two and two together as I noticed the other day some
>soot build-up on the tail pipe. SO my question is beyond changing the
>PCV valve, an oil change, and high octane gas, is there anything else I
>can do? I changed the PCV valve, distributor cap, rotor and ignition
>wires three months ago, do you think changing the sparks would help
>any?
>
>Thank you in advance for your time and consideration of this matter and
>your replies.
>
>Cheers, kind regards,
>Steve


Some soot on the tail pipe is pretty much normal on a vehicle with a cat
converter. If there was a lot of it, that would indicate it's running rich, but
if your CO readings were low, it's not rich. High octane gas might help a
little with high NOx, but won't do a thing for HC.

HC is unburned fuel. Anything that can cause a misfire could cause this.
Ignition problems, or a lean mixture would be what I'd look for first. Make sure
the timing is where it belongs. Could also be a dead cat or air injection
system.

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