I don't Blame you one bit for saying to try it first. If the plugs and wires aren't sound you could potential chase the problem. I had a similar problems. The miss fire monitor would show 2 or 3 cylinders with an occasional miss. The miss would move after I preformed a relearn. New plugs then performing a relearn solved it. Basic maintenance never hurts.

I have never personally seen a coil go bad yet on one of theses trucks yet. I have seen Computers and wiring issues but never the coils them self's. The only time I have heard of issues with the coils is when guys mess with the Tuning parameters and burn them up.

 

If its 03 and up the fliter is in the tank....get fuel pressure gauge and see if it push the right amount. You could have an sticking injector also

 

Since some of you missed it. Lol

 

P0446 Evap Vent System performance could be any thing.

Conditions for setting this code:
The ECU fails to detect a drop in the EVAP system vacuum over a calibrated number of seconds with the vent solenoid open.

First thing to check is the Gas cap. Make sure it seated properly. If the sealing ring around the cap is cracked or damaged, replace it.

Look at the freeze frame data from when it failed. Try and monitor the Fuel pressure sensor in the tank.

You should also be able to preform an evap system test with the Solus Pro.

 

More great information thanks. I may try to look at it later this afternoon. % hours of driving then I am done for the day. I have replaced the gas cap however. Along with the fuel pump.

 

Hey Ryan!! what are you talking about on this thread??? I am having that issue where my contertor will not lock up... sometimes my light comes on... Like this am i let it warm up and light was flashing and now its not WTF!! .... My tranny temp gets up to 228...

 

Is this in the truck in your sig?

228 is smoking hot. You need to flush your trans asap, and stop driving it untill its fixed. If that trans went 228 the fluid is junk. Do not ignore it or put it off.

We had to loosen up the misfire counters with HP tuners on one of my 6.0's with a TSP 220R cam, Your running a 224 that im sure has a lope at idle. That will definately cause miss codes. My truck even running flawless would occasionally flash the mil and store some misfire codes at idle and cruising speed. Likely camshaft induced. No issues once my tuner buddy took care of it.

If you did a cam swap, use a good scan tool and complete a CKP variation relearn. If that relearn is not performed after some major mork like that, it could cause erronious misfire counting, flashing MIL, etc. If its counting misfires it will not lock the converter. If its still counting misfires with the relearn performed, contact your tuner about loosening up the misfire counters with HP tuners.

PM me if you have any questions.

Ryan

 

I never did figure this out. New plugs wires, throttle body, relearn all just the other day, cam position sensor, nothing makes it go away. It only shows up when the fuel is low and the misfire and evap leak large show up at the same time. The misfire only shows up at 0 mph on a scanner. You never feel it.
I'm really tired if the cel and wasting money hunting the issue. I'm up for suggestions.
All O2 Sensors have been replaced as well.

Dirty injectors seem like they would be felt at idle or acceleration?
Clean injectors?
Update the PCM at the dealership maybe?

 

It Might need an update, but I doubt it.

More likely the charcoal canister or the Purge valve are the issue. Sounds like the Leak is leaning out the motor just enough for a random misfire.

What are your LTFT and STFT at the time of failure?

 

I don't know about the ltft or stft I don't have access to a scanner at the moment. It throws the code once the tank is low and right after cranking. I'll try to get a charcoal cannister and purgevalve and replace them. The truck is 4000 miles from 200k and it runs and drives great. I just cant stand the cel