Installing headers problems

[ewoolsey]

Alright so i just finished installing my obx headers last night on my ls3 camaro and here are some problems I had. Any help is appreciated.
1. a loud noise when I back off the throttle at above 4000 rpm. its pretty loud and its a funny sound. don't know how to describe it. is it normal with headers?
2. rattle/bonking noise coming from the back. kinda sounds like the exhaust is bouncing up whenever my car hits a bump? where should i look to fix this?
3. When i took out my pre cat 02 sensor the threads like tore off? so installed it with a spark plug anti fouler. is that a problem? also is it bad to drive the car with neither of the pre cat 02 sensors plugged in? my extensions havnt come yet. thanks guys!

[caverman]

Originally Posted by ewoolsey

Alright so i just finished installing my obx headers last night on my ls3 camaro and here are some problems I had. Any help is appreciated.
1. a loud noise when I back off the throttle at above 4000 rpm. its pretty loud and its a funny sound. don't know how to describe it. is it normal with headers?
2. rattle/bonking noise coming from the back. kinda sounds like the exhaust is bouncing up whenever my car hits a bump? where should i look to fix this?
3. When i took out my pre cat 02 sensor the threads like tore off? so installed it with a spark plug anti fouler. is that a problem? also is it bad to drive the car with neither of the pre cat 02 sensors plugged in? my extensions havnt come yet. thanks guys!

1. Doesn't sound normal. Mine doesn't do that at all. Either a better description of the sound or maybe capture it on video for us?

2. My guess is that your cat-back is hitting the cross brace. You need to check to make sure there is clearance with your cross brace. If not you need to adjust your exhaust some and/or add some spacers to the cross brace.

3. WOW...I can't imagine the car would run good at all without the pre-cat sensors. That's what the computer uses to adjust fuel trims. IDK...personally I would really limit my driving with out the front O2 sensors. I definately wouldn't be hammering it until you get your O2 sensors back in.

Sounds like you're going to need to stop by a dealer and get a replacement O2 sensor for the one that's stripped out. That's not an uncommon thing

[Avenging Orange]

The sound, I'm quessing a chirping squeedgy sound, is prob what I had. Leaky manifold gasket. Make sure the gaskets are installed correctly. You should be using the factory gaskets. (they can b tricky). I had to replace the drivers side.
You'll need to push the cat back up as far as possible (I used a tire jack), then tighten down the clamps then the cats/off road pipe. It'll stay put then.
No, It is not good to run without front 02. Do not drive it till you replace it.

[ewoolsey]

shit i didn't know it was bad to drive it like that... i guess ill stop haha. is the exhaust not supposed to rest on the cross brace? i didn't really look i guess. and i bought new gaskets when i replaced them but it doesn't sound like their are any leeks at idle?

[gelboy1015]

Yea, dont let the exhaust rest on the cross brace. There was a member on here who kept having problems with the knock sensors freaking out everytime he hit a bump because their readings were being thrown off from the vibration.

[Corvette-camaro]

I had the second problem as urs , it's common , u just need to do an alignment for the cat-back and add some spacers for the cross brace to make it lower a bit.

[ewoolsey]

Wow thanks guys. I love this forum. Everyone's great. I'll make sure to fix it. Any more help on the other problems will be great

[ewoolsey]

Could the Loud sound when I back off the throttle be because the o2 sensors aren't installed and its running bad?

[caverman]

Originally Posted by ewoolsey

Could the Loud sound when I back off the throttle be because the o2 sensors aren't installed and its running bad?

I guess it's possible. Install the front O2 sensors and find out.

Personally I think you should not drive the car without the front O2 sensors. If you absolutley have to then be slow and carefull about it. No WOT runs or anything.

[ewoolsey]

shit i was driving kinda hard for a day... do you think i did any damage? it seems fine still. strange thing is it was running really well. had lots of power the whole way through. it was way faster than before.

[geaux_tigerss]

Originally Posted by ewoolsey

shit i was driving kinda hard for a day... do you think i did any damage? it seems fine still. strange thing is it was running really well. had lots of power the whole way through. it was way faster than before.

It doesn't really matter since whatever is done is done. Stay off of it until you get the O2s installed. You should tune as well.

The noise you are describing, is it a sound kind of like the opposite of going WOT (eg, kind of sounds like the car is breathing backwards - I realize this sounds kind of wonky). The coast down loudness from high rpms is normal with long tubes.

[caverman]

I honestly don't know how the computer would handle not having the O2 sensor. Since it's running okay my guess would be that it kept the Fuel Trims at the same level that was set the last time you had the O2 sensor it. It probably just can't make any ajustments with it out. Might explain why it's still running okay.

If that's the case then it would probably be okay to drive it but I don't know that I would chance it much. After all if it did happen to go too lean for some reason and burnt a piston then you're out a motor. If it runs too rich it will just run like crap and probably put out some nice black smoke out of the exhaust.

Just try to get some O2 sensors in there ASAP.

[ewoolsey]

Geox tigers that's exactly the sound I'm talking about. So that normal then? Good to hear! Also if it is running to lean will the engine temp go up?

[geaux_tigerss]

Lean will destroy a motor. Part of the fuel injection is quenching heat in the combustion chamber via fuel evaporation. Heat leads to many horrible things.

I think that WOT runs rely on the MAF whereas long term corrections rely on the O2s so you should be okay. I'd still be careful about it though.

[greenmachinedriver]

The ecm will run in open loop without front o2 readings, it will just run a preset fuel table based on rpm and maf readings, but there can be no corections made. Its not unsafe but not ideal either. And you will get crappy mileage because the safe fuel tables are usually on the rich side.

[ewoolsey]

Again thanks guys. I fixed the rattle from my exhaust and it was definately cuz it was too close to the cross brace. You guys have answered all my questions and I really appreciate it. Does anyone have more info on that strange loud noise I'm hearing when I back off the throttle? Does anyone else with headers kinda hear the same thing? If not I'll wait till my o2's are in and check for leaks once again.