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Unread 08-22-2014, 02:41 PM   #1
jsd1991yj
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1991 YJ Wrangler 
 
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Location: hesperia, ca
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Running very rich..... Please Help

I have a 1991 yj 2.5 manual.

I recently went to have my jeep smogged in california. It failed miserably. It is running extremely rich.

I checked the MAP electricla at idle and it is .2-.3 volts, and between .3 and 4 volts while idling. I do not have a hand vacuum pump to check the different vacuum readings.

My question is what else I can check or should look at that will cause the jeep to run rich?

Thank you all for your help and advice.

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Unread 08-22-2014, 03:26 PM   #2
Jeepsr4me
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Spray some carb cleaner around the intake and all the hoses WHILE its running... Even spray around the intake gasket area.
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Unread 08-22-2014, 06:17 PM   #3
jsd1991yj
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I will try that.

I forgot to add my RPMs are about 600-800 on idle once it warms up. My idle is constant and does not fluctuate.
I also had my engine rebuilt about 2 years ago and installed a new O2 sensor at that time, I have installed an Airaid CAD, 4.0 throttle body, the Ford style 4 port injectors, and a DUI distributor, coil, and plug wires.
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Unread 08-22-2014, 06:30 PM   #4
sprngrider
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Post up your smog numbers
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Unread 08-22-2014, 10:34 PM   #5
jsd1991yj
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CO2% 14.4/15.0, O2% 0.2/0.1, HC ppm 95/69, CO% 0.93/1.18, NO ppm 324/458. The numbers are for 15 mph and 25 mph respectively.

Max HC 89/75, Max CO 0.55/0.69, Max NO 721/623.
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Unread 08-24-2014, 04:14 PM   #6
jsd1991yj
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Sunday bump.
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Unread 08-24-2014, 04:31 PM   #7
Jeepsr4me
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Bump all you want but we can not do the test for ya,. I gave you some solid advice. I deal with this issue all time. it is normally the simple things you over look..
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Unread 08-25-2014, 01:04 AM   #8
sprngrider
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It could be the O2 sensor itself or it could be a leak near the sensor causing a lean reading. Could be the CC is on the way out. Your injectors could be leaking. So many things, but your numbers are close to passing.
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Unread 08-25-2014, 06:56 AM   #9
7377H4
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My numbers were similar. Replaced O2 sensor, map sensor, plugs, wires, CC, muffler, and it passed with flying colors. Running rich will fry the cc pretty quickly (a few months), so it is an issue you might want to address soon.
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Unread 08-25-2014, 09:54 AM   #10
Que89YJ
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Its either the O2 sensor or a cracked/loose exhaust manifold.
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Unread 08-25-2014, 10:55 AM   #11
Jeepsr4me
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Quote:
Originally Posted by Que89YJ View Post
Its either the O2 sensor or a cracked/loose exhaust manifold.
Yeap, maybe the OP wants us to come fix it... And I would if i was close..

I love working on these things.
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Unread 08-25-2014, 11:20 AM   #12
Luuca
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on a 91, I'd first replace the o2 sensor. Even just 2 years can end up with an 02 sensor thats wonky but not throwing a code -yet.

The exhaust leak Que mentioned would be my second area to look for. You should be able to hear it, but if you can't, usually a thorough visual inspection will find it. My SMOG guy almost always can tell me why I didn't pass - i.e. what needs replacing.

SOME WORDS OF WARNING: Before you replace the Catalytic Converter in CA, have the shop show you the CAT they are recommending on the LIST OF APPROVED AFTER MARKET CATS for your ENGINE GROUP or TEST FAMILY. If they put on one that isn't on that list, you will have to pay to replace it again. The SMOG stations are now required to verify that the CAT you have is one from the CARB List of approved CATs for your vehicle. Ask me how I know....


F*!$ CA SMOG RULES!
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Unread 08-25-2014, 03:33 PM   #13
mike134
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You said you replaced the distributor and plug wires, I assume you also replaced your spark plugs? Did you use the copper core or platinum? The jeep likes a hot copper plug.

If you're running rich, they may be fouled already. I'd pull them, clean them, check the gap, maybe even replace them. Then warm the engine up on the highway and go back for testing if its free in CA.

Also, check that your air filter is clean.

Are you burning any oil? If so, try a thicker oil until you pass your test, it may help keep it out of the combustion chamber.
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Unread 08-25-2014, 05:33 PM   #14
jsd1991yj
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I sprayed all around the intake and vacuum hoses and there was no change in the rpms.

I did change the plugs also. They have probably less than 15000 miles on them since they were installed.

I will check my exhaust system for cracks but as of right now I dont hear any air leaks from the exhaust system. Im pretty sure its going to be a good reason for a new exhaust system. I just dont want to lay out the money and not find out what caused it to go bad and fry the cat. I did not know about the different cats and the carb certs on them. Thanks for the info LUUCA.

The engine does not burn any oil and im currently runing 10w30.

Im also waiting to find a fuel pressure guage so I can test the pressure at the fuel rail.

Thank you everyone for all of the info.
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Unread 08-25-2014, 06:15 PM   #15
jsd1991yj
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[QUOTE=mike134;25124738]You said you replaced the distributor and plug wires, I assume you also replaced your spark plugs? Did you use the copper core or platinum? The jeep likes a hot copper plug.

If you're running rich, they may be fouled already. I'd pull them, clean them, check the gap, maybe even replace them.QUOTE]

Why do the jeeps like the copper plugs over the platinum or other fancy ones? Im currently running the E3's and haven't had any issues with them yet. I also have the DUI ingnition system which throws a hotter spark than the factory system.
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