2005 lariat with the 5.4 with 130,000 miles. I have change plugs and all of the COPS and now if I hit the accelarator hard to down shift the engine stutters and barely accelerates. I get different codes each time I do it. PO301, PO308, PO300, PO301 and PO304. It wont do all at the same time just two at the time. My edge basically tells me it is a misfire in one of the cylinders. I am hoping it is something else causing these codes to come up. Any thoughts would be great.

 

pull the COPs off and inspect them. rotate them to another side of the engine 1 at a time.

if the problem moves around, you've found it. Many guys have had similar problems with their COPs.


or, you might have cracked a plug. hope not.

or you might have a plug not gapped properly and it is fouling up

 

I'll put money on it you've got a Catalytic convertor out of it. Can you power break it and make is miss? If so, Disconnect both exhaust pipes at the exhaust manifold(just loosen the nuts and pull the pipe down an inch to open up a gap between the pipe and manifold). Get back in the truck and power break it again and see if the performance improves. We've seen alot of Cats fall apart in these causing tons of problems w/ driveability.

 

Would a screwed up catalytic converter throw codes saying it is a cylinder problem? I have not tried the power breaking but reving up the engine with no load is not a problem.

 

Broken plug or a bad coil or fuel pump would be my experiences. Has fuel pressures been tested starting at the injectors and working back to pump?

 

my truck did that when one of my plugs were broken, if i took it easy it was fine but if i punched it or ran a gear to high rpms it would sound bad and throw a code for a misfire on no5. but yours is all over the motor. you have an edge what setting is it on and what fuel do you use? whats done to the truck motor wise?

 

The edge is on level 1. I use regular unleaded. If it were a particular plug or coil I would think it would throw the same code for the same cylinder not do a different one everytime. I change the fuel filter already hoping that was the problem but no luck. Since this truck hit 100,000 miles it has been one thing or another with the engine and I have grown a little tired of it. I am thinking of putting it up for sale. I hate too but I need less hassle.

 

maybe just to do it return the edge to stock and try it.

 

The fact that the misfires are random, leads me to think Cat. If it was a coil or plug it would stay at a particualar cylinder. Could be a fuel pressure problem, but the only way you can check that is T into the fuel rail where the fuel line connects or get a scan tool that can read the FRP pid from the PCM.

 

the edge reads fuel rail pressure do you know what it should be with no problems? and do you check it at idle?