Thread: is it norm. to have a strong smell of gas to come from the exhuast?

to finish the title, is it normal to have gas smell coming from the exhaust when running an aftermarket exhaust. not too familiar with gp's, ls's mostly and it is normal when going to headers or removing the cats. to be more specific my 97 gtp has flowmaster exhuast and nothing else done to the exhaust, so stock headers, dp, cat. its noticable just about anytime its running, so driving or ideling. anybody else have this issue or any thoughts on this?

You shouldnt be smelling any gas from the exhaust if you still have a cat.
Now, if the exhaust is brand new, you will have a burn-in time typically, in which you get some strange smells..but it goes away after some heat cycles...

ya still have the stock cat and the exhaust is deffinately not new

Umm, then you're probably running rich, if you're smelling fuel from the exhaust...

ok, so what would cause it too be running rich? maybe the maf or something?

maf would throw a code.

next question, is it throwing any codes? misfires? check your plugs and wires, you might have a dead cylinder and unburnt fuel coming out the exhaust

no codes, and runs fine besides bogging sometimes which im discussing on another thread which i have been lead to be a possible plugged cat. but other then that, not codes, no missfires

well that would be the reason. it probably messed up the post-cat o2, so it's sending a bad reading and the pcm is making you run super rich

^^ My thoughts..

If its bogging under heavy acceleration, or when going up hill, its probably a Catalytic...

Ooohhhh ok, so if its clogged then its not allowing the post cat o2 to read correctly and since its not reading correctly its trying to compensate by adding more fuel cuz really its only reading air not burned fuel. I get it, so cat it is

Hit the nail right on the head...My car did the same thing.
Grab some headers, and be happy!

Im sorry for cuting in but it seems that his problem has been solved.
I have the same problem but with no boging down. I only smell gas when it just started or its running cold.

what would cause this by the way the car has back fired from a bad plug but all plugs have been replaced

Well, if you have no catalytic converter, its normal to smell some gas.
If you do though, you're probably running a little rich.

On start-up, you will smell some, because the cat isnt hot enough to do its job for a tiny bit.

Could be a bad o2 sensor.

Now if it's a very strong gas smell, then it's running rich as hell.

possibly an ignition issue. check your wires at the coil packs and spark plugs, pull the plugs out and see if one is discolored and such.

the smell is pretty strong outside the car for a couple mins after starting.
One of my mods are a ported tb, but that should make it run lean.
today im going to try to get my dhp working and after that i will pull the plugs again[last time one got damage from high heat]

Hang in a second guys. The downstream o2 (one after cat) does not control any fueling at all in 97-03 car. It has one purpose, to monitor the emissions. That's all. It can only post a code that makes you fail emissions.

Your front sensor in the rear exhaust manifold can get lazy etc and cause you to get too much fuel. That should then murder the catalytic and trip the code for poor emissions, based off the reading from the rear o2.

Since you have some bogging, it's possible you have a clogging cat from the excessive fuel.

wouldn't a clogged cat throw a code too?

Originally Posted by BillBoost37

Hang in a second guys. The downstream o2 (one after cat) does not control any fueling at all in 97-03 car. It has one purpose, to monitor the emissions. That's all. It can only post a code that makes you fail emissions.

Your front sensor in the rear exhaust manifold can get lazy etc and cause you to get too much fuel. That should then murder the catalytic and trip the code for poor emissions, based off the reading from the rear o2.

Since you have some bogging, it's possible you have a clogging cat from the excessive fuel.

Thank you for saying this!! I was thinking the whole time that their down stream O2 wouldnt decide fuel trims.. I was getting lost in my own thoughts

try figuring out a code on a 4th gen f-body v8. 4 02 sensors, 75 bucks a pop just to figure why its getting "lean conditions on left and right oxygen bank". change all of them, reset computer, drive for 10 minutes, ses light, same thing. change the cats or go cat-less and get 02 sims or have a buddy with hp tuners erase the code from the computer