P0304 Code

[jlsat3]

Hello,
Got in my 2013 L99 today and the CEL started flashing with a little roughness to the engine. It goes off, flashes, goes solid. Stabil trac lights all came on too, they went off once, but mostly stay on.

Eventually throws a P0304 code. Car shakes, domelight dims a little with the shake.
-Switched spark plug wires between cyl 2 and 4, reset CEL, still throws a P0304. Sparkplugs are less than a year old.
-Then Swapped plugs, coil, and wires between cyl 2 and 4, still throws a P0304.
-Plug 4 did look to have more carbon than plug 2 before the switch
-Battery seems good with voltmeter

I have a tune that turns AFM off.

Those flaps in my exhast pipe towards the end...the driver side one seems to shake with all this.

I did get on the gas pretty good for a brief moment while getting on the freeway. Started happening after that. Only drove a couple of miles.

Its my daily driver with over 150k miles.

Any ideas?

Thanks.

[ElderJ]

I'm no mechanic, so just throwing out ideas here, but I wonder if it is the fuel injector? You swapped out the coils and plugs and are still seeing a misfire on cylinder 4.

[1JEWLDSSRS]

Check your connectors for that cylinder, unplug it and look at the wires and pins. I have read on her a while ago that someone had an issue with the wiring on one injector, fixed it and the problem went away. Sometimes one of the wires will get too hot and burn thru, or cause a pin malfunction. GL..

[jlsat3]

I'm Stumped....

Switch fuel injectors between 2 & 4, still same code.

Took spark plug out on 4 and ran engine, the plug sparks.

So...
-Plug Fires (not plug, not coil, not wire)
-Has carbon, so fuel is getting in? (not injector?)

Any help is appreciated. Maybe I need to check compression.

[hunter1660]

Compression?

[jlsat3]

I don't know. Was thinking maybe something is wrong with my valves.

[NOT A 45]

Originally Posted by jlsat3

Hello,
Got in my 2013 L99 today and the CEL started flashing with a little roughness to the engine. It goes off, flashes, goes solid. Stabil trac lights all came on too, they went off once, but mostly stay on.

Eventually throws a P0304 code. Car shakes, domelight dims a little with the shake.
-Switched spark plug wires between cyl 2 and 4, reset CEL, still throws a P0304. Sparkplugs are less than a year old.
-Then Swapped plugs, coil, and wires between cyl 2 and 4, still throws a P0304.
-Plug 4 did look to have more carbon than plug 2 before the switch
-Battery seems good with voltmeter

I have a tune that turns AFM off.

Those flaps in my exhast pipe towards the end...the driver side one seems to shake with all this.

I did get on the gas pretty good for a brief moment while getting on the freeway. Started happening after that. Only drove a couple of miles.

Its my daily driver with over 150k miles.

Any ideas?

Thanks.

Your tune does not change the fact that the AFM lifters are still there. I have had a collapsed lifter that would make no noise like most do when they fail. Remove the right valve cover and disable the other 4 coils. Have someone crank the engine while you witness what the rocker arms are doing on cyl 4. Id be willing to bet one of them isn't moving

[SlimeV8]

Originally Posted by jlsat3

Hello,
Got in my 2013 L99 today and the CEL started flashing with a little roughness to the engine. It goes off, flashes, goes solid. Stabil trac lights all came on too, they went off once, but mostly stay on.

Eventually throws a P0304 code. Car shakes, domelight dims a little with the shake.
-Switched spark plug wires between cyl 2 and 4, reset CEL, still throws a P0304. Sparkplugs are less than a year old.
-Then Swapped plugs, coil, and wires between cyl 2 and 4, still throws a P0304.
-Plug 4 did look to have more carbon than plug 2 before the switch
-Battery seems good with voltmeter

I have a tune that turns AFM off.

Those flaps in my exhast pipe towards the end...the driver side one seems to shake with all this.

I did get on the gas pretty good for a brief moment while getting on the freeway. Started happening after that. Only drove a couple of miles.

Its my daily driver with over 150k miles.

Any ideas?

Thanks.

I had this issue for about 3 months. My mechanic would replace an ignition coil it would work fine, and another would go out. Ended up replacing like 5 coils and over a grand later to fix. Hope its not your case. Peace

[jlsat3]

Originally Posted by NOT A 45

Your tune does not change the fact that the AFM lifters are still there. I have had a collapsed lifter that would make no noise like most do when they fail. Remove the right valve cover and disable the other 4 coils. Have someone crank the engine while you witness what the rocker arms are doing on cyl 4. Id be willing to bet one of them isn't moving

How do you fix that? I'll check compression in a couple of days, and tackle this on the holiday weekend.

[NOT A 45]

Originally Posted by jlsat3

How do you fix that? I'll check compression in a couple of days, and tackle this on the holiday weekend.

If one of the rockers are not moving then the head will have to come off and that lifter will need to be replaced. If I'm doing it, I replace all 4 of the afm lifters while I have the head off. Compression is a good indicator of cylinder condition but keep in mind that if the exhaust lifter is collapsed you will still have compression on your gauge. As easy as the valve covers are to remove, I'd check your rocker arm movement first.

[jlsat3]

All the rockers move

[jlsat3]

Finally checked compression in 2 & 4. They are both good.

One thing that also happens is a lot of white smoke in start up and rev.

[gtstorey]

Did you check other cylinders to compare to?

[jlsat3]

Originally Posted by gtstorey

Did you check other cylinders to compare to?

Yes, I checked 2. 4 is the misfire code.