Hello folks, I had headers installed a month ago. Aside from the power increase and a little more noise, the headers weren't that noticeable.

For the past 3 weeks, I've been smelling gas fumes initially at start up, but now also at stops lights. It must really smell behind when WOT.

I figure I might have a loose connection someplace but I thought the ISF was supposed to be really clean anyhow, so why the gas smell. I wonder if the car is now running rich with the O2 sims.

I'm going to have the car checked out for leaks.

Have any of you all experienced this?

 

Get high flow cats.

 

I still have a stock exhaust with secondary cats, plus there wasn't any smell for the first 2+ weeks....I've heard of ppl with the european spec e36 M3 getting into the US somehow, passing US emissions with aftermarket high flow cats...with eventual cat failure. What are the chances of that with headers and the OEM secondary cats?

 

I've been running Sikky headers and the OEM cat back exhaust combination since March and haven't had an issue. Car sounds and smells stock.

 

The car does run a little rich. Also check where your exhaust connects to the headers my gaskets started leaking, replaced them with better ones and haven't had an issue since. The only time I ever smell it now is if Im stationary for long periods of time with the doors or windows open.

 

Thanks for the info. I will check the gaskets.

Aside, have you experienced some muffled pop noise shortly letting off the gas at lower RPMs at low level acceleration. Sounds like some late detonation or ? "end gas" detonation. I wonder if this is from being too rich.

 

I have that, i love it. Its a rich condition thing.

~Dv8

 

Yes I've heard that sound too, nothing to be worked about.

After my road trip my rear bumper was yellow from running rich. Took a little elbow grease to get it off.

 

Infinus and DV8, thanks for the info!

Will get the gasket checked tomorrow.

It's ironic that my ISF with headers, intake, and soon an exhaust is kinda transforming into an american muscle car (except for nice leather, better fit and finish, transmission, electronics, and reliability).

 

Cayman,

Have you run the quarter with your current setup? I'm curious to see what you'd run.

 

Generally a gas smell indicates a gas leak in the engine. The fumes get sucked into the cowl. Check the connections where the metal lines meet the rubber hoses and around the fuel pressure regulator. Look for a stain, the gas evaporates as soon as it hits the air.

 

Yes, it's from running rich. It's normal since one cannot tune the a:f.
Even with my Borla exhaust I get the intermittent backfire at low rpms.

Has anyone with headers done a dyno after a couple hundred miles w/o resetting the ecu?

With the aftermarket headers; I wonder what the power output and af ratio is after the ecu compensating/re-learning. Also, I would be worried of the longevity of the a/f and oxygen sensor with the condition of running rich.

 

With almost identical Density Altitude and the only difference being the addition of headers I went from a 12.20@117.49 to an 11.91@120. Considering the car makes more power with headers and stock exhaust than it does stock headers and aftermarket exhaust I would venture to guess my quarter mile time to be around 12.1@118.

 

I have put on about 1200 miles since my Sikky header install. Yes, I have that sound too, but only on initial startup. This is when the RPM stays a little "high" for about what 20-30 seconds and then lowers to normal idle? Once down down to normal idle, I can barely hear it, barely noticeable. BUT for sure, I do not have any gas/rotten egg smell for sure.