97 K1500 Code P1345

[Cosmos1964]

I'm not much of a mechanic, so I am depending on info from friends to diagnose a problem with my truck. I have a 97 K1500 4x4 Extended Cab with a 5.7 350. It's been an AWESOME truck and now has 180,000 well-maintained miles on it. A few montha go, I began to experience some power loss at higher RPM's when the engine is under load. The check engine light had come on a few months earlier, but I assumed it was the 02 sensor and ignored it for awhile. The problem slowly worsened until a quick acceleration or shift into the passing gear brings on misfires and a severe lack of power. I began by addressing things that I thought it might be.

I checked the fuel pump. It was fine.
I changed the fuel filter and had the injectors cleaned. No change.
I had the cats checked. Twice. They are fine. (believe it or not!)
I changed the roter and cap. No change.
I finally broke down and paid to have the thing scanned. The code was P1345 which indicates the the cam/crank shaft correlation position sensor has a problem. So, we replaced the sensor AND the distributor gear. No change.

Further scanning seems to indicate that when the RPM reach about 1500, the timing adjusts to -28 retarded and it stays there even when the RPM return below 1000. If the ignition is turned off, the timing resets until the RPM reach 1500.

A mechanic friend says he doesn't think it's the timing chain because the values on the scanner increase in proportion as the RPM's increase. I think I understand what he means, but the experts here may have a better understanding.

Anyway, he thinks the problem is either a wire from the position sensor is bad, or the VCM has a problem. He thinks it's likely the VCM because the timing is getting stuck at -28.

Can anyone offer any insight into this problem? I could sure use some help figuring this one out.

Thanks,

Tim

[Kennykbe]

The four most popular things it could be as I understand it are:
1. Cam position sensor or wiring bad. Located in the distributor under the rotor.

2. Crankshaft position sensor or bad wiring, located o the front of the engine near the oil pan and harmonic balancer.

3. Worn distributor drive gear. This was my problem and is fairly common.

4. Slack timing chain.

Hope this helps