YJ failed emissions again

[CD Long Jr]

87 YJ, AMC 258 i6 / 4.2l with rebuilt Carter BBD, Dura spark II, (new rotor, cap, wires and coil). Autolite plugs gapped @ ,035. Nutter by pass.
For inspection, timing was set @ 2 degrees BTDC, mix screws were turned in until engine started to die, then backed out 1/4 turn. Gasoline was regular, no oil change.
Emissions: low HC- Low 293- failed need 220. High 95- passed. CO- Low 0.12 passed, High 3.96 failed, need 1.20 CO%+CO2%-Low 9.29 High 15.84
The tube from the exhaust down pipe was removed by the PO.
Since the test I have run all the regular gas out and refilled with High test.
Any one have an ideas before I wire the computer back in?

 

[CD Long Jr]

Finally passed. Blew out the muffler on the way to DMV. After looking @ exhaust system, I opted to replace everything.

 

[mylittlecj5]

87 YJ, AMC 258 i6 / 4.2l with rebuilt Carter BBD, Dura spark II, (new rotor, cap, wires and coil). Autolite plugs gapped @ ,035. Nutter by pass.
For inspection, timing was set @ 2 degrees BTDC, mix screws were turned in until engine started to die, then backed out 1/4 turn. Gasoline was regular, no oil change.
Emissions: low HC- Low 293- failed need 220. High 95- passed. CO- Low 0.12 passed, High 3.96 failed, need 1.20 CO%+CO2%-Low 9.29 High 15.84
The tube from the exhaust down pipe was removed by the PO.
Since the test I have run all the regular gas out and refilled with High test.
Any one have an ideas before I wire the computer back in?

Not sure if it has anything to do with it or anything, but I always turn the mix screws in till it wants to die, then turn them out 2 full turns...

 

[CD Long Jr]

Engine was set to factory specs. I figure the new Cat did the trick.

 

[IOPort51]

I have found that a 200 mile road trip at highway speed will do a lot for your chances of passing.