OBD2 misfire codes Ford Ranger 2.3l Lima

[hat_man]

This question is related to my other thread. I just wanted to separate it as this one is more of a learning question for me, but may be related to my other problem.

http://ecomodder.com/forum/showthrea...age-35859.html

I have a Ford Ranger with a 2.3l Lima. 4 cyl, 8 spark plugs, 2 coil packs. Just had the plugs, wires and coil packs replaced. Truck is down on mpg by about 6mpg and feels sluggish. I'm not getting any misfire codes. I thought the misfire codes were P0300 (Random misfire) and P030x with x being the cylinder. I only have 4 cylinders so I am assuming P0301 thru P0304. With having two coil packs (I think Ford did this to help with emissions) lets say I had a bad coil pack but it's the one that fires at the bottom of the stroke (secondary?). Would it show a code of P0305 thru P0308 for the other coil pack/spark? Or would it just not register at all because the two coil pack set up on a four cylinder isn't a common set up? I know that P0305 thru P0308 are for engines with more than 4 cylinders, but I wondered if Ford used those numbers to cover the extra coil pack/spark plugs. Or if it doesn't register an OBD2 code for the "secondary" coil pack, how would you know if you had a bad one?

Also, if you had a clogged injector but were getting spark from both coil packs, I assume it wouldn't throw a misfire code as it's getting spark, but you would still have a "dead" cylinder as there isn't any fuel to ignite?

Grasping at straws at this point, but still trying to learn.

Thanks

[Hersbird]

I don't know about Ford, but the Dodge 5.7 Hemi used 1/2 as many coils as plugs and the extra spark is just a waste spark to allow that little trick of using 1/2 as many coils on a crank triggered ignition. The coil doesn't know if it's firing for combustion or waste, it's just firing, because the single shock is just split into 2 plug wires. I would expect it to show as a misfire on both cylinders it services if it fails, but also that random misfire code usually shows up if there are any signs of rough running even if it has nothing to do with a misfire.

On that 5.7 Dodge they use 2 plugs per cylinder and then cross them over to separate coil packs. You basically never will notice the loss of just one pack as you only lose 1 of the 2 plugs on 2 of the 8 cylinders. Heck you could lose 4 of the 8 packs theoretically have a good spark in every cylinder still. Then they changed that at some point I think to eliminate the plug wires, some of the early generation guys use "shorty" wires to also not have a mess of crossover wires on their Hemis.

[Hersbird]

For a dead injector, disconnect the plug wires and crank it to start for awhile, then pull the plugs. They should all be wet with gas, if you have a dry one that injector is not opening.

PS a partially clogged injector will get the plug wet but may cause lack of power or misfire, you would have to pull the injectors to test spray pattern.