Problem with O2 sensors

[killakella]

I recently installed MAC long tube headers on my 99 cobra w/ a Lethal x pipe. When I started it up the check engine light comes on. I scanned the car and it says theres a problem with the O2 sensors. I transferred all the sensors to the same locations on the new exhaust and added the O2 extensions. The O2 extensions I bought were BBK part #1676. When I installed the O2 extensions I noticed the plastic flanges didn't line up with the ones on my car. Both sides had four metal pins in the connector so I just shaved them down and it fit right in. I didn't think it would matter but now I'm not sure. I know now the ones I installed are for a GT mustang. If anyone knows if what I did would make the check engine light come on then please help me out.:bash: If not I just have to figure out which O2 sensor is acting up. Thanks Mike

 

[2001cobravert]

I had to shave the same plastic piece to fit. No issues with mine though.

Did you try clearing the codes?

 

[Un4GivN]

Is your lethal x pipe catted or offroad? If you don't have cats, there's your problem. You're gonna have to turn the rear sensors off with a tune.

 

[killakella]

I had to shave the same plastic piece to fit. No issues with mine though.

Did you try clearing the codes?

I'm glad you had to do the same thing so now I know it's not that and when I cleared the codes it came back. I hate to guess which one is bad now. Anyone know how to tell?

 

[killakella]

Is your lethal x pipe catted or offroad? If you don't have cats, there's your problem. You're gonna have to turn the rear sensors off with a tune.

Its catted

 

[force feed]

I had the exact same problem on my 01. I shaved them down and after the install the check engine light came on. Just so happens the sensors went bad. I replaced them both and no problem since then

 

[killakella]

I had the exact same problem on my 01. I shaved them down and after the install the check engine light came on. Just so happens the sensors went bad. I replaced them both and no problem since then

Yea looks like I'm going to order them to day and replace both. Thanks for the info

 

[01yellercobra]

What code is it exactly? More then likely it's a slow response code. Moving the front O2's back means they take longer to heat up. An easy way to check is to warm the car up then clear the codes. If they don't come back while the car is warm then the heaters need to be adjusted in a tune.

 

[Un4GivN]

One more thing. Is the fault for the upstream or downstream sensors? Even though your x pipe is catted, it still may be the cause.

 

[olgreydog7]

I always threw codes when I had a Bassani catted X. Just turn the rears off in the tune.

 

[zPipes]

Wayyy off base, but I am curious, how do you like those MAC LT's. Im lookin to add a set to my MAC o/r H. You notice much of a performance increase? Mainly I'm interested int he sound, how does it sound. I know your catted so your quiet, but did you notice a difference?

 

[killakella]

What code is it exactly? More then likely it's a slow response code. Moving the front O2's back means they take longer to heat up. An easy way to check is to warm the car up then clear the codes. If they don't come back while the car is warm then the heaters need to be adjusted in a tune.

Ill try this tonight and see if it works. Man we just had a big quake hit here in the D.C. area nothing like california tho.

 

[killakella]

One more thing. Is the fault for the upstream or downstream sensors? Even though your x pipe is catted, it still may be the cause.

Its for the upstream sensors. They are high flow catts if that matters.

 

[killakella]

I always threw codes when I had a Bassani catted X. Just turn the rears off in the tune.

But would that effect the emissions when I get them done?

 

[killakella]

Wayyy off base, but I am curious, how do you like those MAC LT's. Im lookin to add a set to my MAC o/r H. You notice much of a performance increase? Mainly I'm interested int he sound, how does it sound. I know your catted so your quiet, but did you notice a difference?

I love the way it sounds with the long tubes on it, alot deeper sounding. I also have borla stingers on it so its loud as all. Im just waiting on my first ticket in it for noise violation, it sounds like a nascar. I think it sounds better than any other setup ive had on my cars. I could post a video of it if I knew how to.

 

[01yellercobra]

But would that effect the emissions when I get them done?

No. The rear sensors are only there to make sure the cats are working. The computer looks for a difference between the front and rear readings to make sure the cats are working. That's why some high flow cats throw the code. They don't make enough of a difference and the computer reads it as a faulty cat. FWIW, I've been to a referee station in CA with my rear O2's turned off and not even connected and they didn't notice.

 

[killakella]

No. The rear sensors are only there to make sure the cats are working. The computer looks for a difference between the front and rear readings to make sure the cats are working. That's why some high flow cats throw the code. They don't make enough of a difference and the computer reads it as a faulty cat. FWIW, I've been to a referee station in CA with my rear O2's turned off and not even connected and they didn't notice.

If your car can pass out there than I know mine will pass here. Off topic hows a 5.9 quake feel compared to what your used to in CA. Everyone here was going crazy cause its the biggest to every hit here, but I know were all babies for freaking out.