FI X w/"Fumey" smell when cold

[geekdaddy]

My 81 FI X has a MWB performance head and allison's header w/cat in the exhaust but is otherwise stock. O2 sensor is only a few years old and properly connected to the ECU. I've checked and re-checked timing -- looks ok. Starts right up every time no matter how cold. But smells very fumey while warming up for the first few minutes. After it's all warmed-up it doesn't smell much (or at all).

Also idles very stumbly/rumbly while warming up and then purrs like a loping fat cat when warmed up. If I recall correctly, the rough cold idle coincided with my installation of the performance head.

Thought perhaps my cold injector was overdoing it. But the car won't start when cold if the cold start injector is unplugged -- so it clearly needs it.

Interested in hearing from other forum members on this.
Does your FI X also smell gassy/fumy during the first few minutes of operation?
Looking for some ideas here...

 

[Dan Sarandrea (Phila)]

Everything costs something....the power increases from a bumpier cam and bigger valves and ports are going to cost some degree of low end smoothness. An aftermarket FI controller/system would help, but now you're spending another $1,500 +.

 

[beezee]

FWIW, my stock '83 stumbles and idles too slow when it is cold.

 

[geekdaddy]

Thanks fellas -- kinda figured the cold rumbly idle was the result of perf mods and it's not a big deal -- just looking for ideas in case I missed something easy. I wouldn't install an aftermarket ECU to try for improvements.

 

[Paul Stoltze]

You probably thought of this, but there is a throttle bypass valve that lets more air in while the engine is warming up. Have you checked to make sure it is opening up?

Paul