Author Topic: Passing Smog  (Read 811 times)

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Offline 95 Lowbuck

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Passing Smog
« on: November 19, 2023, 06:47:37 AM »
Had trouble passing my 1995 2.5 YJ, high NOX always seems to be the problem.
At 200k I had replaced the Cat thinking it was time. It passed but two years later I had the same problem.
The mechanic at the station explained to me that the Jeep was running too lean to fire up the Cat and that aftermarket Cats are notorious for it. He finally got it to pass and I asked how he did it.
He told me that he pulled a spark plug wire while it was running, letting unburnt fuel to reach the Cat,
then plugged it back in still running. He rechecked again and it cut the NOX in half.
1995 YJ RioGrand, 2.5, AX5, 231 T.C., A.A. SYE,
D30, XJ D44, Truetracs F+R, CV D.S. F+R, 4.88's
R.E. 4" STD., 33-10.50 BFG KO2's on stock rims.

Offline Jeffy

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Re: Passing Smog
« Reply #1 on: December 21, 2023, 08:52:31 PM »
I always make sure to drive the Jeep around and do some highway driving if you can.  Going to the closest guy isn't always the best as there isn't time for the engine to really heat up the cat.
Youtube Channel:
My Jeep:
"If the motor car were invented today, there is absolutely no way that any government in the world would let normal members of the public drive one."