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Hello guys a newbie here. I jus bought my 93 cadi Seville 4.6L north star. The problem is it keeps failing emissions test here I jus installed cat which brought down all gases but HC. It isn't showing codes but it did throw p046 once then didn't. I know hc is cuz of unburned fuel but I have changed spark plugs new oil cat new air filter and it's still failing. I need some asistence thank you :( I am new to cadies. I have even Cheked o2 sensors they r working good according to pd33 and 32. I have high oxygen in exhaust as well as my engine isn't idling smooth like it's shaking a lil bit at idle. Could be pluged fuel filter? :( otherwise it drives normal no problem at all...could it be injectors on either bank causing lean or rich condition?....thanks again..

Edited by burhan93STS
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Hello guys a newbie here. I jus bought my 93 cadi Seville 4.6L north star. The problem is it keeps failing emissions test here I jus installed cat which brought down all gases but HC. It isn't showing codes but it did throw p046 once then didn't. I know hc is cuz of unburned fuel but I have changed spark plugs new oil cat new air filter and it's still failing. I need some asistence thank you :( I am new to cadies. I have even Cheked o2 sensors they r working good according to pd33 and 32. I have high oxygen in exhaust as well as my engine isn't idling smooth like it's shaking a lil bit at idle. Could be pluged fuel filter? :( otherwise it drives normal no problem at all...could it be injectors on either bank causing lean or rich condition?....thanks again..

Check the rubber plenum between the throttle body and the intake for cracks and air leakage.

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(E046) .................................. Right to Left Bank Fueling

If you have unburned fuel, its possibly leaking injectors, a bad Fuel Pressure Regulator would not cause a right left imbalance, but I would check that also.

I dont believe that its easy to check the injectors on a 93, maybe someone will chime in on this

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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good news is i have managed it to pass the emissions by putting 3L of methylene hydrate in the gas tank, taking out the air filter,unplugging the charcoal canister and unplugging the rear PCV vavle which brought the HC down enough so i can pass the air care....now i have passed emissions it means i can insure it and drive it around but i wanna fix the cause of the high HC plus my engine is not running at its full power capacity i can tell...how can u check for the leaky injectors without opening the head cover?....any electrical way? or i m stuck wit only one way? Thanks...again i DO NOT have any codes and i checked the o2 sensors by going into self diagnostic mood (pd33 and pd32) and they r swinging below .3 and above .6 volts so it means they r working gud?...plus i connected the gas analyzer and i have high oxygen presence in the exhaust....which is why my CO is super low and Nox is okay...any suggestion?

Edited by burhan93STS
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