we need a better understanding of what your are seeing thats telling you it is 2 and 5. so far we have heard a code for a random missfire. is it actually saying misfires for 2 and 5?

 

All you PCM knows is there is a issue with that coil. That means that coil is having trouble the issue could be either 2 or 5 not just 2 and 5. So one injector could cause the issue. Also because motors are not perfectly balanced (fuel trim wise) there is normally one cylinder that acts up before the others as you lean the motor out.

Picture this, if you have a volume switch on you dash that controled rich/lean and you started to lean the engine out very slowly one cylinger would start missing first, this is due to variation in intake design, injector operation, any micro vacuum leaks, intake miss match or slight variation in compression could be the deciding factor on which cylinder misses first. The reason I said check everything else before swaping injectors is because you may have one injector that is just a little weaker then the rest so the miss will follow it even tho the injector is within factory spec but the real problem is the fact the fuel regulator is not working.

That fact the miss goes away at wide open thottle makes me think even more that it is a lean issue. With the throttle in WOT (pedal greater then 80%) then PCM goes in to emergancy mode. Since this could be a safty situation the fuel trim no longer needs to meet any emission and the fuel trim dumps fuel in with power being the focus not MPG or emission. WOT also tend to ignore some sensor inputs and run on a predefined fuel mapping so sometimes a car will work better at WOT if there is a sensor issue.

 

How does the pcm determine what cylinder(s) misfire?

 

In most cars misfire is detected by the crank sensor. Each time a cylinders fires, the rotational speed of the crankshaft is momentarily increased. The PCM knows when each cylinder should fire, so if this momentary acceleration is not detected, the PCM assumes that a particular cylinder has not fired.

 

So if the crank sensor is detecting the the crankshaft slows down during the power stroke on cylinders 2 and 5 at high rpm. And the mil is flashing indicating that the injectors are not shuting of when the missfire is detected and the it could damage the cat. Why would the mixture be lean and what would cause those two cylinders that are ignited by the same coil to slow down the crankshaft instead of incresing the speed of it like it suppose to.

 

If you have a lean missfire it is just that a missfire. Meaning no fire happened. The PCM handle the cylineder in pairs so it is going to report the pair that has the issue. If you move the bad injectors it may report 1-3 next. Again that assume its a bad injector. Have you cleaned the MAF or checked the Fuel pressure yet?

The fact ther system is reporting random missfire mean it is seeing misses in other cylinders and the fact it gets better under hvy throttle all point the fact it is NOT a secondry ignition issue. (Coil,plug wires,plugs). If you still think its a coil you can buy spark testers that have a built in resistance and they can test your system.

 

As Gorn said. IMO the engine is not getting enough fuel to handle a heavy load. The fuel pressure at idle may be OK, but under load and high RPM the fuel pressure may be going low. Not enough fuel volume being delivered to maintain proper pressure. I would check the fuel pressure at the time the engine starts to misfire. May require an assistant to look at the pressure gage while the car is being driven.

 

Someone posted the other day they duct taped the fuel pressure gage to the windshield at first I laughed but after I thought about it I was like thats a good idea. I have adapters that reach into the car but most gages will not.

 

LMAO. That reminds me when the throttle cable broke on an old Alfa that I was road testing. Removed my booth laces and tied them to the throttle lever, left the hood open on the safety latch, and worked the throttle by pulling on the laces. It was interesting getting the left hand and clutch pedal coordinated, but made it back.

 

Sounds like the fuel filter to me. Had the same problem and it was a $30 easy fix.