I got 2 half in. dual flowmaster with two hi-flow cats. The reason I gave my exhaust info is that I don't remember smelling a burnt rubber smell before I got the new exhaust. It only smells on fast idle, so that means here in st.louis it kicks into fast idle every time I start the car during the fall-winter. It doesn't smoke,but a small amount of gray smoke does come out when I first start it but after a few seconds that smoke goes a way. After that smoke goes away its just the usual white warm up gas that comes out of every car in the car. The car only has the smell when it idles once I kick it down to normal idle and drive the smell disapears or is not as noticeable.

... a burnt rubber smell...
Are you sure there isn't a hose or a wire resting on the exhaust manifold?

:mrgreen:

Do you have a small oil leak around a valve cover maybe? A little oil burning on a manifold you would smell at idle but going down the road the air flow would carry most of the smell away. Just a thought.

The burnt smell is the strongest near the exhuast tips in the back of the car. Its not that strong up front. Perhaps describing it as a "rubber burning" smell wasn't the best way to describe it. The only word that comes to mind is that it STINKs like something when on fast idle.

Does it smell like rotten eggs (a sulpher smell)?

The sulphur smell from the exhaust, is caused by running the engine/catalytic convertors under a rich condition. Under relatively lean conditions, the sulphur found in gasoline is converted to sulphur trioxide, then during the rich running condition the sulfur trioxide is converted into hydrogen sulphide (rotten egg smell) within the catalytic converters.

I'm assuming you still have the stock 1986 E4ME Q-jet. You are probably running very rich with a fixed MC solenoid dwell when you first start the engine (open loop). After the engine warms up and the CCC goes into closed loop, the computer will control the MC dwell based on the O2 sensor feedback and will lean out the air/fuel mixture reducing the smell.

My $.02

:mrgreen:

Hey 87Elcamino,

the smell is a rotton egg smell. So what I understand from your post is that this smell is normal? Or should I make the gas flow leaner. And if this smell is normal how come I didn't notice it when I had the orginal single exhaust a few months ago? I would like it to smell more like a muscle car(the gasoline smell) if it has to smell like anything. And if I can't get the rotten egg smell to go away, will this affect me from passing the emission test ( Missouri's test is only a gas cap check and how much carbon mon. comes out of the exhaust pipe check).

What I'm saying is, at cold startup your air/fuel ratio is very rich because the carb is dumping more gas into your engine than it needs when it's on high idle and the choke is set.

The catalytic converters are just doing what comes naturally.

:mrgreen: