Installed True Dual Exhaust & idles fast runs rich

[Robb212]

I installed true dual exhaust on my 1989 Bronco XLT with a 302. (Both cats are gone) Now the truck idles very fast at start up and the smell of gas and exhaust is very strong. My gas mileage also went down. I cant be the first person to do this. Any tips or pointers? THE 02 SENSOR WAS RE-INSTALLED ON THE RIGHT SIDE OF THE TRUE DUAL EXHAUST ONLY.

 

[Krafty]

did you re-install your O2 sensors when you put the new exhaust on?

 

[miesk5]

yo ROBB,

Also, With No O2 sensors, it will run rich and set of the Check Engine Light/and/or give you a Diagnostic Trouble Code (DTC)

And w/No Cats, it will do same

Overview; "...The mechanical AIR system uses a belt-driven pump as well as a check valve to deliver air into the exhaust system (at the first cat) where requiretd. The belt-driven air pump runs continuously so a bypass valve and/or diverter valve is used to direct airflow to the exhaust manifold (upstream air), the COC catalyst (downstream air), or directly to atmosphere (bypass/dump).

The Mechanical AIR pump flow check monitors the HO2S signal at idle to determine if secondary air is being delivered into the exhaust manifold (upstream). The air/fuel ratio is commanded open-loop rich, the AIR bypass/diverter valves are directed upstream, and the time required for the HO2S signal to go lean is monitored. If the HO2S signal does not go lean within the allowable time limit, a low/no flow malfunction is indicated. If the vehicle is equipped with a COC catalyst, the downstream air delivery as well. The air/fuel ratio is commanded open-loop rich, the AIR bypass/diverter valves are directed downstream, and the time required for the HO2S signal to go lean is monitored. If the rear HO2S signal does not go lean within the allowable time limit, a low/no flow malfunction is indicated. The PCM outputs that control the bypass and diverter valves are checked for circuit continuity..."

Source: by miesk5's WORD file of useless info, trivia, and some important facts

Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19

The engine temperature must be greater than 50° F for the Key On Engine Off (KOEO) Self-Test and greater than 180° F for the Key On Engine Running (KOER) Self-Test.

Run it around to heat the engine up and shift thru all gears incl Reverse. Then turn off all accessories/lights, etc.

Make sure A/C is off and transmission is in Park (automatic) or in Neutral for a Manual & release clutch.

Do Key On Engine Off (KOEO) portion first.

Look Codes up in my broncolinks.com site using the new Search function.

And Post em here according to:

KOEO

&

KOER

 

[Robb212]

did you re-install your O2 sensors when you put the new exhaust on?

YES THE 02 SENSORS WAS REPLACED THO I HAVE ONLY ONE 02 SENSOR ON THE RIGHT SIDE EXHAUST ONLY.