i have a 93' fd and for the past few months my car has been accelerating very jerkey and the idle is very rough. i changed the plugs and the wires and no luck. my mods are apex'i pfc, j&s knock sensor, magnacore wires, ngk plugs, cosmo fuel pump, 1200 cc ingectors, hks evc IV, hks hyper ground, gready turbo timer, 3mm apex seals, apex'i gt intercooler, fluidyn aluminum radiator, sylicon vaccume lines, cold air intake, gready underdrive crankshaft pulley, odessey mini batt. i tried adjusting the sensativity of the j&s knock sensor and no difference. any help would be greatly appreciated cause i am out of ideas.

 

so is it like the title says that your front leading coil isnt firing?? OR is your car driving weird and anything could be the problem?

try switching the plug wires of the leading plugs where they connect to the coil and see if the rear leading now wont fire.

im just not sure of your question to go on further with help

 

I don't think its firing since the plug comes out black but only that 1. the symptoms seem 2 me as if its not firing.

 

Have the factory service manual?

 

is the j&s sensor mounted correctly???
use the manual to check for the spark dont just assume its not firing because the plug is black

 

is the j&s sensor mounted correctly???
use the manual to check for the spark dont just assume its not firing because the plug is black

 

check the leading coil, the harness, double check the wires, and spark

you can take out the fuel pump relay take out one plug at a time of the leadings and connect them to the wire and ground the tip of the plug...now try to crank the car. You should get a HUGE blue flame.

 

i checked the spark this morning and both wires are sparking. my j&s knock sensor is not mounted, they just sat it next to my power fc when it was installed.

 

I really cant help any more without looking at your car

the things that affect the spark are the coils, the harness and the ground on it, the wires and plugs. If it just started happening without you doing anything then I would say maybe replace your leading coil and see if that fixes it. First check the ohms on it first though in both places.

 

Can't you connect a timing light to each wire to see if each are firing?