I own a 2003 Dodge Ram 1500 with a 4.7-liter engine that just started giving me a problem that I can't figure out. The trouble started after I had filled the gas tank and added a bottle of STP gas treatment (not right away, but when I had reached approximately 1/2 tank level).
The engine would start to miss if I tried to accelerate, and later started loosing power (couldn't go any faster than 63 mph). I thought I might have gotten water in the tank so I treated it with a bottle of dry gas treatment and refilled the tank. It seemed better at first but it didn't last. I then noticed that my fuel pump was making a buzz/whistling noise. I tried another bottle of gas treatment (fuel injection type), but it didn't help.
When I had the computer checked it showed a CODE 1. The pump is still making noise, the motor runs good (no problem when first started) but starts acting up when the engine reaches running temperature, and gradually gets worse the more I drive?
A misfire (one or more cylinders shutting off), and a lack of power from fuel contamination or not enough fuel pressure, typically produce different types of symptoms on the road.
The misfire is a more abrupt bucking sensation while accelerating, usually caused by a loss of spark (or fuel) to a particular cylinder.
A loss of power from insufficient fuel (total pressure, not one injector shutting down) is a somewhat smoother, bogging down of the engine -- depressing the gas pedal with a lack in response.
Not sure where the "code 1" came from. Code P0016 is the lowest numerical diagnostic trouble code your powertrain control module can display, and this one deals with a crankshaft/camshaft timing misalignment.
That noise from the electric fuel pump inside the fuel tank should be our "red flag". That, along with a lack-of-power, tells us to hook up a fuel pressure gauge so we can test fuel pressure and fuel quality at the same time.
There are other areas that can cause similar symptoms, so have the trouble codes double-checked with a scan tool, also.