WellI've had a misfiring problem for awhile now. I took off my intake manifold to fix some leaking intake gaskets, and found the #1 and #3 injector plugs crossed... I haven't touched them since I had the 383 built and put in, so they were like that when I dynoed, and I made 432... I kind of figured power would be down. Would crossed injector plugs cause a misfire? I'm letting the RTV cure before I run it, so I won't be able to see if the misfire code is gone till tomorrow. Anyone know what crossing two injector wires will do?

 

It should cause a missfire situation. Obviouslly the computer is sending the signal for cylinder 1 to fire, but it sprays into cylinder 3 and vice versa. Since the raw fuel is in the cylinder, there is probally still an igniton when the spark plug fires, so you don't notice it. I'm sure you have power on the table like this. The fuel is meant to be burnt when the injector sprays, not when it is lingering in the cylinder.

 

Ah if this fixes my misfire, I'll be the happiest man on this board!

 

It will cause a slight irregularity in the cranksahft movement, probably enough for the crank position sensor to pick up. Its not a complete misfire. If the injector fires when the intake valve it closed, the fuel simply vaporizes when it hits the hot valve and gets pulled into the engine on the next intake stroke. But that small change in injector timing is enough to alter the accel-decel pattern of the crank the the PCM is mointoring via the crank sensor.

The 93's for example, use batch fire injection.... all four injectors on one bank fire simultaneously once per crank rev, and 93's don't "misfire".

Back in the mid 90's, Electromotive sold an ignition system that totally eliminated the Opti. It was called the Super Direct Ignition/Opti-Eliminator (SDI/O-E). It worked using a crank wheel to measure crank rotation, then used that signal to synthesize the high res and low res pulses from the Opti. Unfortunately, using only a crank wheel, it was possible for the injectors to get synch'd to the wrong rotation of the crank. The only noticable effect of running the injectors 180-deg out of phase was a slight stumble when the engine was cold, and the fuel was not vaporizing on the valve. The thing that killed the SDI/O-E, and caused them to stop making it was the problem the out-of-synch injectors caused with the OBD-II misfire detection. All the irregularities of the out-of-phase sequential injection had the SES light flashing constantly.

 

Well thats really my problem... car didn't really misfire, it would just throw the code. I'll see tomorrow.

 

My car definentally misfired and occasionally threw the code when my injector wires were crossed. I believe a shop did that as a joke and it was a really mean one because i pulled every plug and wire and checked everything before i could figure it out.