Wondering what maybe causing my lt1 to be running very rich black smoke under wot. Misfiring and rough idle when warmed up. It struggles to rich higher rpms. Have brand new plugs and wires. Wires are on correctly. Smell fuel at idle when warm and under acceleration. I'm leaning toward the optispark but wanted to get some opinions on it. I can pick up an ac Delco opti for 180 through a connection I have at a shop. Also how much is a rebuild kit for an optispark go for?


Side not car has zero emission components they have been deleted I.E. Egr valve and air pump a/c deleted as well. Throttle body coolant bypass.
Car has shorty headers magnaflow catback exhaust 4.10 rear gears slp cai and a full hurst short throw shift. And a 165 degree thermostat.

 

Not sure exactly what that means, but hopefully you have not deleted the pre-cat O2 sensors. Assuming you still have them, how old are the O2 sensors? What brand?

At any point, have you scanned it for codes?

There are several possible causes:

-Faulty O2 sensor(s) or shorts in the wiring.

-Misfires - misfires cause it to run rich. Fuel and air enter a cylinder, the fuel does not burn, and the fuel and air get dumped into the exhaust. The O2 sensor sees all that air, and tells the PCM that bank of the engine is running lean. PCM adds fuel to that bank of the engine, causing it to run excessively rich.

-Exhaust leaks before the pre-cat O2 sensors - same result as above.

-Excessive fuel pressure

-Leaks in inlet ducting between the MAF sensor and the throttle body

-Large vacuum leaks

 

I still have all the o2 sensors. I do not have an egr valve or air pump. No exhaust leaks or vaccum leaks. I've pulled the plugs and they are clean. The plugs wires are all connected correctly. Last year the car would burn the tires off 1st thur 3rd gear. Now it just bogs out when I punch it from a dead stop. Put a new maf in less then 200 miles ago. Idles rough when it warms up.

 

And the headers haven't burned through a plug wire or two?

 

No the plug wires all seem fine. Car shakes at 1000-2000 rpms. smooths out but doesn't want to pull. Back fires when I down shift at around 2200 rpms.

 

How did you determine the wires "seem fine"? Did you spray a light mist of water on them, and look for arcing in the dark?

Have you checked the fuel pressure? Check the vacuum line for the fuel pressure regulator for wet fuel.