My 2004 has me baffled. In the process of changing my spark plugs I noticed a broken wire on passenger side fire wall. It was later discovered that the wire connected to the passenger side knock sensor. I changed the plugs with a great deal of difficulty and repaired the wire.
Initially the truck drove excellent, actually better than it had for quite some time. After about a week of driving fine, it all of a sudden ran poorly.
I did a diagnostic on the vehicle, it said the driver side plugs were mis-firing. After several days of replacing parts and running further tests, it was discovered that the drivers side of the engine isn't working.
With the engine running, I disconnected each coil pack wire with no change in the engine's sound while idling. I disconnected one coil wire on the passenger side of the engine, the engine dies.
I have switched everything I can think of and still can't get the drivers side of the engine to work. The coils are getting voltage and will spark when tested with a spark plug. The injectors are getting fuel and when checked, they are getting voltage.
During the tests, I did notice that plugs on the side that isn't working were dry and didn't smell of gas. Is there a relay that controls particular injectors?

Any suggestions will be very helpful.

 

im not sure about the newer engines but the older ones (pre 97) had a relay for the injectors, the newer motors might have a relay for each bank!

 

Thanks Bow Tie, the problem was the variable cam timing solenoid (vct). It was a relatively simple fix, the hard part was diagnosing the problem. The computer pointed to that part, but named several other things also. Since changing the solenoid, the computer doesn't show any fault codes.
Engine is running better now than it has in the past several years.