[TreDirtyFive]

I thought it was just me for a while but every time I start the car now, it smells severely rich. I'm curious if it is simply smelling like that because both sides are open now as opposed to one. But then again...rich can mean diminished power (?) hence many saying they have lost torque or high end power. I have had the mod for 1000 or so miles. Any insight? Thanks.

[Sparky66]

TreDirtyFive,

Doing a Golf Tee Mod could be the culprit. What you are smelling may be mis-interpreted as a 'rich gas smell' but may just very well be carbon monoxide along with nitrogen oxide and some unburnt hydrocarbons (basic emissions and pollutants).

Your cats will allow more pollutants and gas emissions to escape from your exhaust when cold starting your car. The longer it takes for your cats to come up to temp. the more emissions you will smell. Having the valve always open on cold start ups is slowing the cats getting to their effective operating temp. sooner.

There is a thread already discussing how to do the golf tee mod and what people think it's purpose serves here:

http://www.e90post.com/forums/showthread.php?t=202467

Look in particular at this post by me here:

http://www.e90post.com/forums/showpo...2&postcount=12

[TreDirtyFive]

That could very well be the case but it definitely smells like gas without any doubt. I'm going to plug it back in and drive for a bit to see if it changes back. Should be the best troubleshoot. I'm thinking of getting "Rev" for my Iphone to see how much fuel trim correction I'm getting with and without the mod plugged in. I'll report soon. Anyone else with any ideas?

[Ilma]

This may not apply to your geographic area, but where I am it is below freezing.

If temps have been dropping where you are, then you could be experiencing some cold start fuel enrichment (aka choke).

I noticed more of a smell on startup when it got colder.

Wasn't there as much back in the summer.

[TreDirtyFive]

It has been warm here in SoCal actually. Breaking some records I believe for this time of year. But that could be true since I start it early in the morning or late at night.

[Sparky66]

Originally Posted by TreDirtyFive

That could very well be the case but it definitely smells like gas without any doubt. I'm going to plug it back in and drive for a bit to see if it changes back. Should be the best troubleshoot. I'm thinking of getting "Rev" for my Iphone to see how much fuel trim correction I'm getting with and without the mod plugged in. I'll report soon. Anyone else with any ideas?

That little valve may have more to do with Fuel trim than people realise !!!!
That first minute, when the engine and cats are cold ithe ECU will adjust trim to aid and allow the cats to do their job. Once they reach operating temperature it will revise back this fuel trim.

The oxygen sensors mounted on the Downpipes closer to the engine and upstream of the catalytic converters, measure and tell the engine computer how much oxygen is in the exhaust. This control scheme allows the ECU to make sure that the engine is running at close to the stoichiometric point for Air Fuel Ratio, which is 14.7 : 1.

The ECU increases or decreases the amount of oxygen in the exhaust by adjusting the air-to-fuel ratio to make sure that there is enough oxygen in the exhaust to allow the oxidization catalyst to burn the unburned hydrocarbons and CO. The catalytic converters do a great job at reducing pollution but only if they reach their correct high temperature operating range very quickly
So when you start your car cold or in a cold weather environment the catalytic converters take longer to come up to temp and do almost nothing to reduce the escape of gas emissions from your exhaust until they do come up to temp.

Heating the catalytic converters as quickly as possible at cold start up, is a good way to reduce emissions. The easiest way to heat the converters quickly, was to insert a flap valve in the exhaust tail pipe. Remove this feature and on a cold start up, you will smell the unburnt fuel smell until the cats heat up.

[Sparky66]

How sure are you of that?
Where do you base your assumption from?
What makes you think your aftermarket exhaust would pass all emission tests that car manufacturers spend millions on to comply with emission laws.
To meet the ever increasing stringent emission laws which all car manufacturers have to abide by, they are forced (If they want to remain in business)to improve on reduction and against the escape of emission gases.
Using flap valves as a part of reducing cold start excape of pollutants is nothing new. Some manufacturers even have Preheat elements at the cats to bring up the temp as quick as possible. Look it up........you may be surprised.

If you do the Golf Tee mod or eliminate the valve, you may notice at cold start up, the smell coming from the exhaust. That's basically it ! Then after a minute or two as the cats temp increases and they warm up, the smell will disappear.
Remove the valve and the cats completely............you will smell emissions 24/7.

[pdjafari]

all i know is that removing the valve and adding cyba's quads has made my stock exhaust drone slightly and its alot louder, never expected exhaust tone/note to change w/ just tips!!

[Ghost170]

It does make sense that the valve help reduce emmisions at cold start by helping it heat up the cat agree with you there. However does it affect the car as a whole, besides the cold starts? I do know having an exhaust does not affect passing smog, since we do it when the car is warmed up, unless you may not have that second cat. Isn't also the purpose of the valve to reduce exhaust noise which some consumer may not like? I personally did not smell gas when the car had the plug unplugged, nor smelled gas when friend's car had an aftermarket exhaust. Not saying you are wrong, just wondering? Can unplugging it really do harm? and having an after market exhaust do harm, since permanently delete the valve?

[Ghost170]

Most cars I had before had aftermarket exhaust with stock cats, and had passed the smog test. I would understand if had no cats.

[Sparky66]

It won't affect the car as a whole, at all. It's all about compliance.
It's just another means for the beaucrats to impose another stringent emission law compliance on us. Design of combustion engines to continually improve on and reduce emissions even further will be implemented in the future as governments try to meet carbon /greenhouse gas protocols. Who knows how long before we are all driving "Green" powered cars.............it may not be as far as some think.