Ay I got a 99 yukon 5.7 that'* throw the p1345 code. I thought it was the timing chain at first. There'* a rattling noise for like 30 or so seconds wen started up cold, and will just stop.

Actually it sounds like a cracking more, you can hear it if you turn the truck off while it'* warming up, sounds coming from drivers valve cover

Phaser rattle? Shouldn't last more than a few seconds.

1999 Yukon 5.7 doesn't have phasers. It sounds like an oil pressure issue, and the lifters are taking a long time to get pumped up. Those engines are known for eating intake manifold gaskets, letting coolant into the engine oil, eating bearings, and subsequently having oil pressure issues.

How long have you owned it?

How many miles have you owned it?

Crackling sound when it is turned off from the driver'* side valve cover?

Moved to GMC forum as this is a Yukon.

I just got it August 4th. 219,900. I just changed the oil qnd filter yesterday. There wasnt any metal or coolant feel liquid in it, just really black. But would coolant in the engine throw the p1345 code?

Ill try it posting a video of the sound in a little

No, my coolant reference above is related to low oil pressure which could be related to your crackling-on-startup issue if it is lifters etc. not pumping up quickly. My point above is that likely at one time or another, your engine may have had the intake manifold gasket fail, causing damage that could lead to oil pressure issues. That having been said, if it is crackling when it is turned off then it isn't that.

Regarding the P1345, your distributor timing is likely advanced or retarded more than the PCM would prefer. On this engine, crankshaft position is read at the crank, and cam position is read at the distributor. You might be able to adjust it by turning the distributor, but if it is too far out of whack you'll have to pull the distributor and turn the shaft a tooth or few depending on how bad it is.

I need to get new computer glasses. Don't know what year I thought it was. Yikes I'm losing it. That'* OK I've lost it before and somehow it finds it'* way back home.