i have a 92 civic dx with a ls motor in it just recently put on a skunk 2 catback system and now i have a nast smell when it sits there just idleing and im gettin horrible gas mileage wuts goin on with that? someone help me!!!!!!!!!

 

haha, thats why ur exhaust system has an O2 sensor, its sensing how much air is coming out and flowing through that exhaust and ur car is more then likely using more fuel. I would get under and check all ur fuel lines and make sure nothing is rubbing against ur exhaust. Make sure ur exhaust is bolted up pretty tight.

So if you're using more gas ur running rich I take it. CHECK all o2 sensors. I installed an OBX type R 4-1 stainless steal header and Full 2.5 in cat back with a stock cat and I went from about 275-300 miles per tank to about 220-240. I lost a lot of gas mileage, I also had a AEM CAI on there to boot and well it doesnt help at all when you have a lead foot!

Did you replace the cat converter too? That would be another reason that it smells real bad and getting horrible gas mileage.

Hope it helps

 

i didnt replace the cat but i was thinkin maybe its just clogged and i didnt notice any difference in gas mileage till after i put the exhaust on. i think it maybe loose on the bolts that connect it to the cat itself

 

Yea I would def double check everything. check your o2 on the cat, could be bad! Those are expensive too just for that sensor! Did you hand tighten the bolts on the exhaust? Check for any leaks. You should be able to hear them anyways, it will sound raspy. What year civic was it? The cat could be old and gettin bad, you can replace it with a Hi Flow cat for like 100 beans but be careful with the emissions here in NY, they are pretty strict with that and it will make your car a lot ****** louder! Hope it works, I'm sure its something minor.