"Start with basics"
Thanks- I just dont look foward to tearing down the front of this thing- especially having to discharge the A/C to do it- but I think it is inevitable- I keep thinking it will clear itself up, hasnt happened though

 

Tore apart the front of the engine saturday, chain was off 2 teeth on bank 1. redid both chains, now runs Great! no more codes.
Thanks for all the help here.

 

That is a strange one. Glad you got it solved!

 

How hard of a job was it? I actually bought a new motor and was debating just fixing this one.

 

Depending on what is wrong with your existing one, and the milege, and how clean it is inside. I had 155K on the engine that came out, timing chain had jumped and dropped a valve through a piston. The inside of the engine was dark brown, not sercviced well bedfor I got it. The new engine I put in runs better than the one I pulled out, even before it broke. If you are talking about the difficulty changing the engine, i had it mostly done on 1 weekend, finished it the next. It wasnt that bad compareativly. On the timing chains, it is not nearly as bad as I thought it would be. started Saturday morning around 8 and finished around 5. everything comes off easy- goes back easy. Not a quick job,just make sure you are lined up 1st as it is a close clearence engine. The shop manual shows exactly how to line up the marks.

 

Well the motor has 84k on it. I would say it didn't have an easy life as there is not one panel on my truck without a dent in it. I have yet to even pull the plugs as I know what an ordeal that can be.

 

I understand- You might pull the left valve cover and see how clean the engine is- if dark and dingy I wouldnt waste me time- if clean and shiny - the oil has been changed regularly
and not beat too bad. Good luck

 

khacker:

was your motor running poorly throughout the rpm range or only at idle? I have this same sensor code and it really is scaring me. I bought a lariat 2008 with 65k miles this past monday, and three days into it the truck started to idle VERY rough. I initially thought it was missing, but when I would rev it up to bout 2000 rpm, it would clear up and be fine. When I am running the highway everything is fine, runs like new, but only when I get the truck to the turnrow and idle it starts sounding VERY bad. I dont have MUCH mechanical knowlege and that means I will be going to a mechanic shop. The check engine code reads PO340, Camshaft Position Sensor Circuit Malfunction. Is it possible the sensor is fouled up and the sensor is causing it to run poorly? I have heard of sensors going out and causing what sounds like a mechanical problem.....I just dont know. Since I bought the truck used, and opted out of the ext warranty, I will be footing the bill for this completely.... Any advice or opinion would be VERY appreciated.

 

Sensor is cheap and easy to change if you want to verify. It sits right on the front of the motor. I believe it is a 10mm and a plug. The left drivers side you need to pull the intake snorkel to get to it. You could swap them if you don't want to buy a sensor. See if you get a code for the other side.

 

ok, so I tried the swap, cranked the truck, and it runs like a new motor. put it back, and it runs fine too. I ran it to work, approx 45 miles, then it started acting up. so I assumed it had something to do with the truck warming up and then triggering a problem. I told this to my dealer, they immediately went to the tailpipe where there was less and less exhaust coming out, once it almost stopped coming out, the truck started doing its funny idle. They pulled the converter and it was completely clogged with "gunk." They ordered the replacement converter, and took the other one off to do a comparison run. It ran fine, after letting it warm up. It makes sense that when the exhaust started backing up and misfiring, the motor started to throw sensors. It COULD be as simple as that. They ran it for several runs around town through red lights and stop and go, and it ran fine. WHO KNOWS! MAYBE WE COULD BE ONTO SOMETHING!

 

ALSO,

The more I think about it, the more I can see how the misfiring and backfiring COULD POSSIBLY throw the timing BACKWARDS a tooth or two. But I dont see how fixing the timing would fix the original problem.

Food for thought.

EITHER WAY, my dealer said they will cover the parts, labor, materials, everything to make this deal right. They gave me a new 2010 loaner until I get mine back, Im gonna suffer through until my 2008 gets fixed.... So, high hopes for tomorrow!