Stephen92

Ok so i have been back and fourth a 1000 times with shops etc all trying to get some info on what is causing this smell... I have an 01 is300 with megan racing headers to a magnaflow exhaust. there are no cats or anything in-between. Obviously my cel is on.

Now, when driving and the windows are down I get a dreadful smell that honestly will eventually give you a headache, same thing if I have the ac on with the vent pulling from outside instead of circulating.

I bought the car this way and want it back the way it should as far as smell goes.
What do I need to replace or add to get this smell to go away.

If I could go back to stock headers for a reasonable price I would. But please can someone that isn't guessing and knows what this issue is please help me with this, it honestly makes me want to just sell it! I love this car and want to fix it!

Need4Speed

Had same problem. The problem is your not running any CATS. Your smelling what is coming out of your exhaust with out CATS. I say add a HIGH FLOW CAT to eliminate that smell without sacrificing a lot power.
Running Catless does help, But that smell is what you will have to live with . Not to mention how bad that really is for you..

Stephen92

Ok so where exactly would I put the cat? Sorry for the stupidity, Also what would you recommend? If I was to replace the header what header would you recommend? Link if you have one please. Thanks for the response. Would it be best to just find stock parts or could I completely eliminate the smell inside the car with windows down by doing what you are suggesting with aftermarket?

Would also like to add at the exhaust shop, they pointed out discoloration in some of the piping that was below the floor boards in that area, so right off the header, they said it was due to no 02 sensor there and it was dumping more fuel and it was causing it to get much hotter than it should. Any ideas on that?

And just 1 more so everyone can get a better understanding of the setup.

megan racing headers. No cats and no resonator. straight pipes from headers all the way back to the magnaflow exhaust.

darkgt23

geez how loud is that thing? yea with out a tune its going to dump fuel improperly. usually a cat goes close to after the header I would just search for the cheapest hfc and throw it on it should help and be cheapest option

Stephen92

Its not too loud, mind sending me some links and do you also think that will kill the smell? I was also told that I cannot tune it with the stock ecu... I would just tune it that would save money lol. How would I go about doing that as well?

darkgt23

easiest way would be to weld in a hfcat do you have a check engine light on? there are a few ways to tune you could run a simple piggy back since its not too crazy but even then I've heard they aren't receptive to changes I would rather someone else guide you on that part.

darkgt23

but yea a cat will deff help out with the smell stock one would do the most but a high flow will keep it similar to what you have now

Stephen92

I do have a check engine light on yes for that as well lol, can you link me to the stock and a high flow cat as well please? Would either or get rid of the smell?

Stephen92

bump would really like some direction

darkgt23

just do an ebay search would prob be your best bet

darkgt23

http://www.ebay.com/itm/2-5-Magnaflow-Universal-59956-Catalytic-Converter-High-Flow-Spun-Metallic-Cat-/170862884170?pt=Motors_Car_Truck_Parts_Accessories&hash=item27c838b54a&vxp=mtr

darkgt23

just a general since the cat in the stock is is on the y pipe don't know if you could re put that back on your set up would prob be easier just to weld something like this in they come in all sizes 2 1/4 to 3 inch usually

Stephen92

Alright, finally got it done, put in an high flow cat where the"pre-cat" should be.
had every link welded up... I have to say 1, the car accelerates so much smoother and quicker, it drastically changed how the car not only sounded but performs, very happy! Now they said that the header will more than likely leak again as once you weld stainless it will find somewhere else to crack.... So I am looking at the cheapest best options cause the header does not have the converters on it..... so I need to replace it and I think I will be golden! I am looking for the cheapest thing i can get that is good. What I have found is oem but I would love cheaper lol.

http://www.ebay.com/itm/01-02-03-04-05-LEXUS-IS300-EXHAUST-MANIFOLD-PIPE-OEM-/221620224262?pt=Motors_Car_Truck_Parts_Accessories&hash=item3399984106&vxp=mtr

darkgt23

just keep scanning the forsale in here I doubt it will crack again at least for a few years. stock headers are cheap when they are just laying around someones apartment or storage shed ask me how i know we have a stock z06 exhaust in my back yard right now lmfao

Stephen92

Lmfao! If you happen to see one try to remember me I will be searching as well.