'99 5.7L... ping/knock/rattling when cold?

Caver Dave

Caver Dave

Just holdin' it down here in BFV
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Mar 10, 2005
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Hooterville (24171)
Since the weather cooled off (sub 70* at night) and after a couple tanks of Premium (see Chips thread)... the Sub has a NASTY noise when cold!

Thought it could be:
  • Fan Clutch, but can hear it in the crossover pipe when first started
  • Weak lifter, but it doesn't go away until the engine is at operating temp (closed loop?)
  • Piston slap (heard several were notorious for it), but it *sounds* like ping!
  • "Noises" coming *FROM* the engine forward, *NOT* the CATS, etc.

As soon as it hit's 180*-190* it goes completely away, no noises at all once it hit temp (possibly hitting closed loop?), even under load (heavy accel/towing).

With a 180K+, I figured the topend might be carbon'd up, but thought it'd be more prone to making noises once warm (everything heats/expands), rather than cold?


Might still run a can of Seafoam/MMO through the fuel system and another down the topside...

A guy from FSC said it could if the timing was VERY retarded, but thought it'd be so far out then, the ECM couldn't adjust it far enough when in closed loop? Plugs, wires, & cap appear to be fairly recent, but may start there for GP.

Any other ideas, thoughts, or tips? :beer:
 
transman731 said:
if the timing is off it will set a camshaft/crankshaft correlation code.(p1345)
Click to expand...

Thanks Lee!

I forgot to add that the SES light is NOT lit (lamp does work prior to cranking), but I guess there could still be codes stored?

IOW, no issues other than the noise (& perceived damage?) until it warms up... then magically it goes away! :confused:
 
Yeap... I'm guessing that the timing(fuel?) curves are static and the knock sensor dummied until it reaches temp anyways?

Was thinking about a ScanGaugeII for other uses, just not sure it's gonna be granular enough to troubleshoot this issue.
 
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