It doesn't seem to matter how cold it is out side if the engine is cold it will run rich and blow a bit of the unburnt fuel out the back. (no it is not oil, i have been checking it religiously, same with the coolant) Once the engine gets up to about 120 or a bit higher it seems to go away. The car has done this for as long as i have had it, but with it getting colder here in Illinois and my drive to school not really long enough for the engine to warm up, not to mention the high gas prices i would like to fix it if possible. Stock t-stat stock air box (got tired of the open element causeing a loss of power on hot days), pretty much stock all around. Any ideas? LO3 91 rs auto. 81,000 miles

 

Try dropping your fuel pressure. If I have it too high, during warm up cycle my exhaust is so strong in smell it'll make you cry...

 

Weird thing on the 83, I don't know about later, but the engine is given max possible fuel until you rev it up. After that it checks the engine temperature, and if it is warm enough, it starts to cut back on the fuel delivery. If the engine is cold still, it resets to giving maximum fuel - until it is reved up again and it once more checks the temperature to see if it should reduce the fuel flow.
If you drive really slowly, you might not open the throttle open enough to get the ECU refering to the temperature sensor, so you get buckets of gas wasted and risk poor cylinder lubrication.

 

I haven't tampered with the fuel pressure so in theory it is running at the factory settings. Its kind of annoying knowing that i am dumping fuel out the back.

 

Fuel injected cars run in an enrichment mode when first started. This is commonly known as open loop. Basically, it defaults to pulsing off a fuel table. It doesn't take into account fuel pressure, so if higher, you get a super rich enrichment on top of the fact its pulsing faster for enrichment.

When certain conditions are met; certain time running, coolant at 140 F or exhaust above a certain temp allowing o2 sensor function, it goes into closed loop mode and bases the fuel delivered off the various reading from all the sensors.

If something's changed fuel pump, lines, fuel filter, kink in the line or anything that could affect fuel pressure that would be why your running rich.

The other reason if FP hasn't changed is you're not getting enough air into the car to burn with the fuel.

Finally, if your spark or timing is off, then a lot of fuel can pass unburned, if valve train is out of alignment, not enough compression or valves staying open, this too can cause fuel to pass unburnt.

 

Ahh there we go i had forgotten about timeing. I will see about fidleing with it at some point here soon. Thanks.

 

on my '88 TBI car. It turned out to be a bad water temp sensor connection, showing way too much resistance. The car lost a water pump, and showered this connection with water. 6 months later, the connection had corrosing in it.

The TBI was just DUMPING fuel into the engine, you could see it coming out of the injector in a stream (it should be a wispy vapor trail at best). Check the connection on your temp sensor, and my next guess would be to replace the sensor, it might be bad. If you can read the codes, it might have one for "temp sensor out of range".

Good luck.