The car will start and idle fine, if you quickly snap the throttle it will backfire through the intake. If you drive it and begin to load it up ( 50% throttle or so ) it will misfire like an ignition miss and if you let it coast and snap the throttle it backfires. If you roll into the throttle it usually won't backfire and pulls strong. Once the car warms up ( 10 + minutes of driving ) misfires are completely gone and driveability is perfect .... even throttle snaps are fine.

Built 406 with accel dfi gen 6. I initially assumed it was in the tune, but the problem was not always there and the tune has not been touched recently. Coolant temp sensor is fine.

 

Try pulling a spark plug I suspect youll find its on the white side. 2 common problems of what your describing is bad ignition timing or a lean mixture im guessing its the latter of the two. Now you say that after 10 mins of driving or so it cleans up that may be becaus it is now in closed loop operation and compensating for the forementioned problem perhaps? Sorry not terrably familiar with Accels gen 6 DFI set up but figured ide throw in my input anyways seeing as how you didnt seem to be getting much help.

 

Wow I would NOT drive the car when its doing that, might just create some ugly repair jobs for yourself. I had the same problem as I was tuning my new Demon. The best tool is a cheap air to fuel guage at pepboys. It has three wires, power ground and a purple one that goes straight to your oxygen sensor. This will help you get your mixture setup correctly. As far as the misfires.. Rolling thunder seems to be on track with the plug check. I was actually being arrogant with mine and had a wire in the wrong spot. 2 and 5 were in each others place lol opps. Also might want to double check to make sure everything is tight and no wires are burning up or grounded out if you have headers. Let us know what you find.

 

I pulled the plugs and found 4 of them to be white, while the other 4 seemed normal. If in fact I am assuming it to be a wire problem ( which were all in the right places ), why would it clear up after a while? Does weak ignition become less of a problem with the engine hot?

 

Personally i dont think its an ignition problem I think its a fuel delivery problem. Its not terrably uncommon to see spark plugs white on one side because this is a batch fired system if im not mistaked (again not familiar with your set up but i assume it probably is) 4 are fired at a time and it sounds like that side has a problem. Why was it bad when the motor was cold and seemingly cleared up when the motor was warm? The fuel mixture needs to be richer when the cars cold then when its hot so a problem where a car runs lean will be more noticeable when the cars cold. I would ohm out your injectors and check your grounds/ 12V supply.