I bought this truck a year ago knowing it needed cam phasers. 10 months ago I changed the cam phasers and VCTs and it ran great up until a week or so ago. Out of nowhere I start feeling a mis at idle so I just assumed it needed plugs (I wish I had read the code) so I changed plugs and coils. Didn't work, still misses at idle and spark knocks 2,000-2,500 RPM only under mild acceleration but runs fine otherwise. If I hold it to the floor I won't hear anything but if I put it about half throttle I hear it spark knocking.

So now I have new phasers, new VCTs, new plugs, new coils and new cam sensor. Truck ran perfect for 9 months and now its got me baffled.

I've tried everything I've read on here and I'm so ready to drop it off at the dealer and just practically give them my life savings. They wanted $2,200 to replace the phasers only and I did it in 7 hours start to finish. But, did I screw up somehow with the timing? That was 10 months ago I've put thousands of miles on the new phasers without ever seeing a check engine light.

Please help!

 

Did you put new tensioners on the timing chain?

 

No, cam phasers only. If it were a guide or tensioner wouldn't there be some noise? If you were standing outside of the vehicle with the hood open you wouldn't even know it was missing till you touch the truck and feel vibration of the miss. There are no noises coming from the timing cover. I did mine by only removing the valve covers so I didn't change any of those things.

 

Gotcha, the tensioners are known for gasket failures on removal.

I'd check your timing marks again, make sure the phaser bolt is tight, all that good stuff

 

Yeah, I'm finally coming to the conclusions I have to go back inside... Not easy getting that valve cover off. I think I'm gonna get it to top dead center then stick a camera scope down the vct hole and see if I can see timing marks or damaged tensioner. Then if I have to open it back up. Wish me luck. Anyone had this problem please let me know. 1 single code and nothing more. No mis fire codes no nothing. Just P0012.

 

The thread title ("Everything was already replaced") - WAS a little misleading. @Patman is probably right on, and depending on the trucks year model raises the question of how many miles? It likely needs new tensioners & tensioner arms/chains/chain guides and potentially other stuff. But possibly not new phasers - provided the replacements were OEM.


One word of caution. Trying to 'verify' timing marks with a bore scope (or even by opening her up) is not prone to ready success. Once the engine turns over the Chain Timing Marks will NOT align with gear marks again for 122 engine revolutions due to the odd relationship between chain links to gear teeth. Plus - I'm sure you could never see the crank sprocket timing mark with the bore scope. But if it were one tooth off - you should have a P0340 code.

The P0012 code (over retarded bank 1) is set if the phaser's ACTUAL position (as determined by the CPS signal) is more than 10 crankshaft degrees OFF from the PCM's requested timing retard for more than 5 seconds. [See the attached page from the Motorcraft OBDII Theory of Operation manual for the 2004 5.4L.] 10 CKS degrees is not much - JUST 5 CAMSHAFT DEGREES. That much cam positioning error can occur from worn/stretched chains or broken guides.


Regrettably - that's where I think you are.

 

Thanks for information. Everything you said makes sense. I guess it's time to pull front cover and just replaced the chain guides and tensioners.

 

I wouldn't immediately throw parts at it. Need to open it up to inspect and diagnose what's is happening