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Unread 07-10-2011, 08:16 AM   #1
Registered User
1989 YJ Wrangler 
Join Date: Jul 2007
Location: Mansfield, TX
Posts: 16
Emissions CO Inspection Fail Texas

I failed inspection on the CO readings. Here is a breakdown: HC 190 High Speed and 182 Low Speed (Pass). C0(%) 3.53 High Speed and 2.98 Low Speed (Both Failed). C02 (%) 12.1 High and 12.5 Low. 02 (%) 0.2 High Speed and 0.2 Low Speed. NOx (ppm) 882 High and 1122 Low (Pass). Dilution (%) 15.6 High Speed and 15.5 Low Speed.

I put a Motorcraft carb on since last inspection. I think the cat and PCV valve is still good and the jeep has NEVER run better than it does now. Of course with the Motorcraft carb just about all of the vacuum lines went into the trash can.

The only weird thing going on with the jeep is a high pitched whistling sound when the jeep initially accelerates under load. Almost can't be a vacuum leak unless it's in the throttle body somewhere. I may have a manifold leak? Who knows, and if it's not related to the CO reading then I can live with it at this point.

Can anybody give me a checklist of things to try?

Thanks you for your help.

coyoteboy76063 is offline   Reply With Quote Quick reply to this message
Unread 07-10-2011, 12:03 PM   #2
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1989 YJ Wrangler 
Join Date: Jun 2011
Location: Frisco, Il
Posts: 1,377
Make sure your emissions test was an ASM instead of a 2 speed idle. With the idle test you will fail miserably. (I know from experience and I live north of Dallas btw).
Collin89Sahara is offline   Reply With Quote Quick reply to this message
Unread 07-10-2011, 12:29 PM   #3
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1990 CJ7 
Join Date: Nov 2008
Location: Ga
Posts: 5,145
Try rejetting to the next smaller jet size. When you re-tune tthe carb, set the idle 50 rpms on the lean side of peak.

Make sure your EGR system is working.

Get an air filter that has the proper flow rate for that engine.

Put an OEM spec thermostat in the cooling system.

Fix your vacuum leak, a whistle is telling you there is one.

If you don't know the Cat's history, get a new one.

Change the oil just before your next inspection.
418 miles on 19 gallons of gas. Can't beat the BBD !
Old4X is offline   Reply With Quote Quick reply to this message

emissions , inspection , motorcraft

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