pass emissions with long tube headers

[autoworx]

anyone know how I can pass emissions with long tube headers? I keep getting a code that sensors have a slow response. the oxygen sensor rediness tests pass but the catalyst never does. any way to get around that without changing exhaust? I have a 99 cobra with an 04 cobra motor. tune is based off a stock 04 cobra tune. kooks long tubes with off road x pipe


I do understand that it is doing that because the o2 sensors are located farther back and the computer is expecting readings with them closer to motor.

 

[Yellazxr]

anyone know how I can pass emissions with long tube headers? I keep getting a code that sensors have a slow response. the oxygen sensor rediness tests pass but the catalyst never does. any way to get around that without changing exhaust? I have a 99 cobra with an 04 cobra motor. tune is based off a stock 04 cobra tune. kooks long tubes with off road x pipe


I do understand that it is doing that because the o2 sensors are located farther back and the computer is expecting readings with them closer to motor.

The cataylyst isn't going to pass because you have an off-road x pipe and a catalytic convert isn't present. Are the rear O2's hooked up? Do you already have a tune on the car? If you have a tune on the car you need to have it modified to increase the time delay for the O2 sensors that will fix the slow response trouble codes.

 

[autoworx]

if it was because of no cats the code would be insufficient flow. the codes specifically say sensor 1 on bank 1 and bank 2. and for the tuner to fix the slow response it sounds like that is not possible to do.

 

[01yellercobra]

He needs to add about 15% to the transport delay and heater duty cycle. That'll get rid of the slow response code. If the rear O2's are turned off for the O/R pipe the monitor will never be ready.

 

[heytonyman]

Some of the import guys use a trick of stacking 2 or 3 spark plug anti-foulers on top of each other to move the downstream o2 out of the exhaust stream. Makes the ECU think there's still a cat there. Never tried it on a Mustang tho.

 

[jpplaw]

Stacking anti-foulers only works sometimes with hi flow cats, and it is highly doubtful that would work with no cats present at all. The slow response code is for the front O2's (sensor 1) and once that is fixed, you will then start throwing 0420 & 0430 codes (sensor 2), if, and only if, the rear O2's are turned on in the tune. The cat monitor will never go "ready" with no cats or if the rear O2's are turned off.

 

[01yellercobra]

You might want to do some research for home made MIL eliminators. They're basically resisters that go in place of the rear O2's.

 

[jpplaw]

an 04 might be able to get away with using the MIL eliminators, but they don't work at all on later models

 

[autoworx]

hi guys so got the car to pass! fortunately being a mustang freak I just so happen to have a catted h pipe for long tubes sitting around. and they had some factory universal cats so they function well. I then took out the front O2s and heated them up to get them clean. they were motorcraft and looked decent. I did have the slow response flip on pending a few times. fortunately the evap takes forever to set. the trick that worked for me and my car was I noticed the slow response only went on once I was in the city. So I kept it in a gear lower than normal and it would clear out the pending code. as long as its not pending when the evap is set(gas tank 1/2 to 3/4 and IAT between 40 and 100 drive 10 minutes 45 to 60 mph) and or when the drive cycle is complete it would be good to go. sweeeeet!

I was so excited when it passed I just held it in went right home n tore out those cats! thanks for the info guys

 

[autoworx]

and I have done the anti foulers. they did work on my 96 cobra with bbk long tubes. that's why I still the catted pipe