Intermittant P0351 but no performance issues

Greetings all,

I've had my 03 TRD SC 4WD for 4 years. Occasionally I will get a CEL with a P0351 when I start the truck. Less frequently a P0340 and a P0351. I have changed the appropriate coil and the plugs. Sometimes the error may not come up for months, sometimes it may surface on 2 consecutive days.

The truck does not miss or have any difficulty starting. I reset with my scan guage and all seems well. Never a CEL unless on startup. but I did notice that if I turn the key on and leave it there for a few seconds I can replicate the error code.

Weird. I wonder if anyone else has experienced headscratching issues like this and possibly solved them.

Thanks

 

Have you had any luck figuring this out? I'm encountering those same two codes and the engine will "skip" every now and then. It's not happening EVERY time I start the truck, but it is quite often. If it does throw the CEL on, it does it as soon as the truck starts, and I've noticed that when it actually throws the two codes (P0340 & P0351) I hear a click under the hood as the key turns to the "ON" position. Seems to have a humming sound coming from the rear of the engine block somewhere more towards the passenger's side, also (almost sounds like a fan running, and no it's not the blower inside the cab). Have noticed that my fuel pump will run constantly with the key in the "ON" position when this happens.
I haven't gotten to tear into it as it's been freezing cold lately, but that's what I've found so far. Surprising to see nobody has relied to this yet, as I have ran across a couple posts about this very issue of the same two codes with no luck on an answer.. I'd love to know what's going on

*EDIT* I did recently purchase the truck a week or so ago, and the P.O stated that the engine would die out on him.

 

I have not. The P0340 is only about every 10-20 times, I can replicate the P0351 by leaving the key in the on position for more than a few seconds. No noise here that i can detect and the truck runs fine. Mine was a repo so I have no idea of the history.

Thanks and good luck, maybe we can figure this out and help some other folks along the way.

 

Do you happen to have the TRD 7th Injector computer hooked into your harness? Also, when your truck is idling, will the RPM's drop significantly when you turn on your high beams/pass. I'm starting to think it's an issue with the truck not getting the correct voltage during starting. I have checked my ground wires, but I haven't checked power. Fixed a TON of wiring cluster F***'s under the dash from the PO. Still doing the same stuff. As you said before, if I don't start the truck in one swift motion from OFF > START, it will throw the code if set in the ON position for too long without the engine running.

 

Also, the PO stated the truck will die occasionally after reaching operating temp. Said the idle will drop and try to stall, leading me to believe there is a severe electrical issue. The battery kept dying when he had it too. I have since ripped out his hack-wired alarm system, and HID spot lights. I have a brand new battery in it now and seems to be holding charge. As stated above, the RPM's seem to drop severely when I pull on the high beams, turn the blower fan on, or somehow pull a somewhat large load from the alt.

 

Check out this video of what it's doing: https://www.youtube.com/watch?v=iYjpBVOkKzc&feature=youtu.be