Need advice: Various electrical codes- Alternator?

[RonD]

1995 and up should stay above 1,000 RPM until speedometer is below 5MPH
It's an emissions thing, below 1,000rpm the engine has to be run Rich or it will over heat so emissions are high at idle RPMs

 

[BarnesAM]

Ok, so I’ve driven it for about a weeek now with the new parts installed. As always, it runs great, very smooth, no issues in terms of drivability. However I just gassed it up and ran the math/numbers, and it’s still getting about 16.5 mpg. That’s so low I think a 4.0 would beat it. So, I’m thinking that camshaft sensor code isn’t just coming from a flutter, that sensor must not be working right, therefor the computer is just making its best guess as to fuel timing etc, and the efficiency is shot.

So.... I’ve got to figure out what’s the deal with that sensor circuit. Yikes! I already did the wire, the sensor, and the computer. Well, I’ll look to see if it’s putting out a signal at all, and start a process of elimination I guess. I hate electrical problems like these.

 

[RonD]

First pull a few spark plugs
Check color, light brown to white means good burns, darker color means rich burn, so yes computer is running engine too rich.

Did we cover the actual miles vs shown miles?
i.e. tire size vs speedometer/odometer errors

The spark plugs are the end point, they show the efficiency of long term fuel use.
computer and sensors determine the mix but ultimately is has to be burned so spark plugs tell the tale

 

[BarnesAM]

First pull a few spark plugs
Check color, light brown to white means good burns, darker color means rich burn, so yes computer is running engine too rich.

Did we cover the actual miles vs shown miles?
i.e. tire size vs speedometer/odometer errors

The spark plugs are the end point, they show the efficiency of long term fuel use.
computer and sensors determine the mix but ultimately is has to be burned so spark plugs tell the tale

Good thought. I'm out of town for a week, but I'll check the plugs as soon as I'm back. I suspect they'll show it's running a bit rich (it must be, at 16.5 mpg on a 4 cyl). As to miles shown vs. actual miles, the door jam says OEM tires were 225 70 r14. It now has 215 70 r15 tires on it, which increases tire circumference and mileage by about 3.5%. I've confirmed this with the speedometer vs GPS comparison as well (when speedo says 77 GPS says I'm doing 80-81, or about 3.5% more). So I'm factoring that in when I do the mileage math. In fact, I've rounded it up to 5%, which is overkill. That formula yields me the 16.5mpg.

I'm also going to put a multimeter on the + wire coming from the Cam pos. Sensor while it's running just to confirm if there's a signal coming out of it or not. I know that'll only tell me if the system (sensor, wire, or something) is "dead" or not, that it won't actually tell me if the signal (if any) is working right, but its a place to start anyway. Then I'll check to see if the other tan/red stripe wire is a good constant ground (I assume that's what is should be, correct?). I'll post results. Again, I appreciate all the input and guidance!

 

[BarnesAM]

OK, so I'm back in town now, and need to figure out the pesky Camshaft Position sensor malfunction. My gas mileage is awful. Can anybody give me a step-by-step on how to test the cam position sensor system so I can locate the problem? Is there a way to test if the signal from the sensor itself is good (that would isolate the problem to the PCM)? Should I just try a new sensor? The one I installed was a "standard motor products" model (cheapest on RockAuto), so maybe I should try a Denso...? I'm out of my element here, so I'm just be taking shots in the dark. Not sure what to try. Any guidance would be helpful.

Also- I will check the spark plugs, as I mentioned, but I know my mileage numbers are accurate, so that will just confirm that it's running rich. It's a fuel injected 4 banger getting 16.5 mpg, so it's gotta be running rich.

 

[BarnesAM]

I tried to upload pics of the spark plugs, but it wouldn’t let me. File is probably too large on my iPhone. Anyway, they looked pretty darn good. Light dusting of light brown color, but not wet or dark, and not burned like a lean fuel condimtion. So.... in this case the plugs tell me very little. The truck seems to run great, it just gets horrible mileage and throws the cam position sensor code all the time.