p0303 to p0300

[jinxed13]

so the other day my truck starts misfiring, im not throwing any visible codes beside the good ol p0440 and it states im p0303. so i put new plugs in, ordered some new wires and switched two of the coil packs. now im throwing p0300..


is it safe to assume that i have a bad coil pack? or should i also check something else?

thanks all.

 

[tx4r3g]

Need to wait untill you replace the plugwires frist. A bad wire will make it seem like a bad coil too.

 

[BrianSD_42]

Are you actively throwing the code? (flashing yellow)

I have had several random intermittent CELs.

It has happened 3 times now, usually 2-3 months apart. Each time it is P0300, P0301, P0303 - all misfire related.

BUT I have no other symptoms. No running rough, no flashing CEL, no noticeable misfiring in any way. The only noticeable issue was that the CEL showed up.

So each time I just reset the code and waited for it to come back.. Each time it didn't come back for months and even then the story was the same.

I had a compression test done for peace of mine and everything is within spec.

I am hesitant to start swapping parts to try and solve something that right now isn't an issue. My truck has 217k miles BTW.

 

[jreask]

Are you actively throwing the code? (flashing yellow)

I have had several random intermittent CELs.

It has happened 3 times now, usually 2-3 months apart. Each time it is P0300, P0301, P0303 - all misfire related.

BUT I have no other symptoms. No running rough, no flashing CEL, no noticeable misfiring in any way. The only noticeable issue was that the CEL showed up.

So each time I just reset the code and waited for it to come back.. Each time it didn't come back for months and even then the story was the same.

I had a compression test done for peace of mine and everything is within spec.

I am hesitant to start swapping parts to try and solve something that right now isn't an issue. My truck has 217k miles BTW.

I have the exact opposite happening. Once every couple of months the truck starts to shake/run extremely rough almost like it's running on two cylinders. It happens for about a mile and then goes away. The difference is I never get any CEL when it happens. I am stumped. New plugs, wires, cleaned TB, MAF, etc.

Go figure.

 

[jinxed13]

code is active, and its running terrible. it actually feels as though its running on less cylinders than one. but its only at idle or low rpm.
im going to assume its not an injector issue since the problem moved when i switched coil packs.