Hello Everybody! New here to the forum. Need some help with a 2003 Ram 1500 4.7. Truck has 89k and was recently purchased. Truck is throwing P0016 & P0344 error codes. Starts hard (sometimes takes 3-4 tries) and bogs out at 3000RPM. I'm assuming the ECM is in limp mode thus not allowing engine to rev over 3000. Anyway here's whats been done so far.
Camshaft position sensor and crank position sensor were replaced and did not fix the problem. Wiring harness/electronic system was scoped and found no issues. Timing chains & gears seem to be set correctly.
Apparently one of the heads was changed and my mechanic believes it is a mismatched head. He seems to think a new cam and cam reluctor wheel will fix this. Quite costly with an estimate of $1400. Anybody seen this before? Any ideas?

 

When you say the wiring harness was scoped (???), do you mean that they scoped the CMP and CKP wave forms at the PCM connector?

I've never seen a correlation code on a 4.7, and I'd think that's a secondary code caused by the intermittent signal. With new sensors, it's gotta be either an issue with the tone wheel, the spacing of the sensor, or the wiring between it and the PCM.

If I were attacking this one, I'd start by verifying good power and ground at the cam sensor, then scope the signal wire at the computer.

 

Yes. They scoped the CMP and CKP wave forms at the PCM connector. Any idea where mismatched head theory came from?

 

Not really. I'm unaware of any substantial changes to the 4.7l over the 10 years it's been in use. I've done a few head gaskets on them; They all looked the same to me.

Your symptoms definitely match the codes; the computer seeing an incorrect CMP signal or none at all, and so is substituting an estimated value based on CKP input to keep the thing running. But when they do that, they retard the crap out of the timing. So yeah, it's in limp mode.

Did they verify the physical timing of the cam? You have to pop a valve cover to do so. That's where I'd be at this point.

 

Well still have not been able to find definitive problem. Latest is mechanic thinks it could be the timing chain tensioner which is causing the hard start. As mentioned before, one of the cylinder heads was changed. The one original cylinder head has a decent amount of sludge covering the rockers & valves. He's also thinking this could be the problem causing poor oil flow/pressure. However gauges read oil pressure is fine. Anybody? Engine has 99k on it. Can it be rebuilt? Obviously money is tight in this economy and a new engine is out of the budget...