Join Date: Apr 2002
Location: Colorado Springs, CO
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Emissions failed - Update - PASSED!
First let me start by saying that I thoroughly searched on emissions and took almost every bit of advice ever given on the subject.
The setup: 84 CJ7, fresh 258(<15,000), MC2100, TR upgrade, nuttered.
The day before the test I changed the oil & filter, new Autolite plugs (.045), new wires dist cap/rotor, new air filter, cleaned carb, poured in 2 quarts iso alcohol, set timing (I think).
Day of test I drove on the interstate for 30 minute prior to test (engine/cat very hot).
HC PPM 1422 @idle 95 @ 2500 RPM ---> Max 400 (FAIL)
CO% 0.11 @idle 0.15 @ 2500 RPM ---> Max 1.5 (PASS)
CO2% 7.4 @idle 12.9 @ 2500 RPM
All the visual stuff passed even though most is not active due to Nutter bypass (ie O2 sensor, Pulse Air, EGR, etc).
The problem is at idle HC way too high. If I can get this fixed I am golden for two more years.
Can anyone tell me what to do? I leaned the idle mix screws as much as possible as well.
I am stumped.
UPDATE - RRICH was right on the money. I had a vacuum leak at the base of the carb where it meets the adapter plate. Once I fixed this reset idle and timing it ran great and passed the idle HC test easily. Thanks RRICH I was skeptical when I first read your post as it seems counter intuitive to be lean when HCs are high. Hopefully this update will help anyone in the future with similar issues.
Thanks for you help.