Engine codes

[tonypaul]

I havnt drove my truck since before xmas but I have started up a couple times to pull in or out of the garage. Normaly I use my remote starter to start the truck but it hasnt been starting up. It would go through its crank cycle but not start. So I went to my back up key switch and it took a cranking of 5 or 6 seconds for it to crank up then it was idling super high. It would go up to around 2500 rpm to 1800 rpm and wouldnt come back down.

So today I thought I try it again. Same thing took a good 6 seconds of cranking before it would start and it idled real high. I drove it around the block and it didnt have no real power. If I mashed the gas pedal to the floor it would bog down. So I assume its in limp mode. I ran my AeroForce scan gauge in scan mode and came up with these 3 codes;
0101- mass airflow circuit malfunction
0121- throttle postion circuit range/preformance problem
0340- camshaft postion sensor circuit malfunction

I cleared the codes and started it up again- same thing it took a while to start, idled high. I didnt drive it just reved it a couple times to see if the idle would come down. Scaned again and 0340 came back up.

This truck was running so good last week. It would fry the tires all the way down the street.... Should I start by replacing the cam postion sensor?

[78bronzechariot]

I don't know how your truck is set up, but those three codes sound like a strange combination. The first thing that I thought of is fuses. There maybe one that is common to those three sensors. On the swap I did in my 67 there are 8 fuses for the engine/pcm/trans ( I don't remember what does what right now). I would check them and see if there is a prob there. I think mass air flow codes will take a little driving come back if there is still a problem with it.

[matthew20061]

That does seem strange all those codes would pop up after letting the truck sit for a while. Its possible it could be a bad ground or maybe a wire got melted on something? Like 78^ said above it very could well be a fuse too. It just seems strange to see something like that pop up randomly.

[tonypaul]

I forgot to add that its a 7.4l Vortec with 4l80e. Im gonna replace the cam position sensor and see what happens.