Upon arriving at one of my shops I am given a 2004 Ford F-150 5.4 liter 3 valve motor. The customer complaint is that it runs rough and the check engine light is on. The vehicle has 117k miles on it and I am told it has always been well maintained. In fact it just had a recent tune up. Sure enough it runs rough and has a MIL lamp on. I also notice a decent rapping noise coming from the passenger side valve cover. I am told by the shop owner that this vehicle has had that noise "forever". Now, noise complaints on the 5.4 liter triton motors are not uncommon. This noise however is excessive.
Well first thing I do is pull codes. I have a P0300(Misfire detected) and a P0012(Variable Cam timing over retarded Bank 1). I also notice that the miss is more of a low speed misfire. It gets slightly better above idle. A quick test drive later and I feel that this truck has other issues besides a miss. It also has a lack of power as well.
Whenever I can I utilize Mode 6 data. Mode 6 simply put is the code before it becomes a code. I use it a lot on Fords with misfires and to confirm Evap code fixes. It is quick and concise. So I check out the misfire TID's(Test ID). It tells me that cylinder #1 is missing like crazy. Ok I have something to go on. Remember on most Fords cylinder #1 is on the passenger side. Remember, our noise? Furthermore, looking at #1 cylinder there is a new Coil On Plug unit and a new pigtail for the coil. Hmmm. As much as I trust Mode 6- I like to confirm. So I disconnect the COP connector and really no change in rpm, pulling #2 COP connector results in a decent rpm drop. Well I found my cylinder. My mind is still fixated on that rapping noise coming from under that valve cover. Another item I check when dealing with misfires is fuel trim-both short and long term. This vehicle has good fuel trim on both banks. That tells me we don't have a vacuum leak or a fuel issue causing the misfire. Next, out comes the low amp probe on the COP unit, nothing wrong there other than a short duration of operation which clues me in to what to do next.. My next step here is to check the actual spark plug itself. If you ever had the pleasure of doing spark plugs in a 5.4 Triton motor you know there is some praying to various deities when doing this job. First off these spark plugs require a special 9/16 spark plug socket to remove properly. Then you have the issue with the lower portion of the spark plug breaking off and staying in the cylinder head. luckily, various tool manufacturers have tool kits to make this job go easier. I felt better knowing that someone recently changed the plugs. I removed the #1 spark plug and.....
Yup, this plug is missing some pieces. Now, where did those pieces go? Could this be my noise? I crank and start the engine with the #1 plug out and hear something fly out.
This is a new plug with a dap of anti seize compound on it. Compare it to the one I took out. So I send this plug home and start the motor. The noise is still there but the miss is gone. I clear codes and road test. The truck has no more miss but still has power issues and a MIL lamp on. Code P0012 comes back. Time to break out the scope and look at some signals.
The Cam sensors give the PCM information on the cam position as well as variable valve timing. I prefer to backprobe at the PCM whenever possible. Thankfully the PCM is accessible. So we break out the wiring diagram and PCM connector views and backprobe Cam sensor bank 1 and bank 2.
Channel 1 is bank 1 and channel 2 is bank 2 respectively. I see an issue with bank 1 already. The amplitiude of the signal is in question for sure. Here is another shot.
Something is messing with the cam sensor signal on Bank 1. Before we go further we need to see if the actual VCT(Variable Cam Timing) system is working. I normally like to do a dynamic check where I ground the actuators on each bank raced up and look for rpm change.
Both banks show rpm change. So I now know we have the ability and we don't have totally clogged oil passages. I advised the shop owner a tear down is in order. I suspect something with the bank 1 cam sprocket or what Ford calls the phaser. All I know it is not going to be cheap. I advise the shop about oiling issues and to really look for sludge. Any sludge and I would recommend motor replacement versus repair.
Shop owner tears it down and the timing chain has substantial slack, the passenger side chain guide is completely broken and pieces are everywhere. Remember our noise. Above is a shot of a cam sprocket/phaser. But, there is absolutely no sludging. Customer decides to fix the truck. I tell the shop to save me the passenger side phaser. Below is a shot of the passenger phaser reluctor ring compared to the drivers side.
It has two bent reluctor tabs. Now, I know why we had that cam sensor pattern. How did they bend? My guess is the the timing chain guide that has been flopping around got wedged and bent them. Below is a shot of the phaser taken apart.
Here is one of the actuator and oiling metering block.
Like I was told this truck was extremely well taken care of. I was asked to retake scope shots to confirm repair after the timing chain, phasers, guides, etc was done. Below is the updated scope shot.
As you can see with my cursor set the amplitude is almost identical. Driving the truck afterwards the noise is gone and the truck has good power.
