1FZ Experts - I've got a noise! (1 Viewer)

Somebodyelse5

Land Crushers
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Hi Folks... been chasing this noise for a while and I finally got a second set of hands to help record the noise. @ncavi rev'd the truck for me, just as it leave idle and feels some load it makes that light knocking noise.

The noise seems heat dependent, and the frequency doesn't change much with rpm. A heat soaked engine, maintaining speed (~45mph) on flat ground, will make that noise constantly and it sounds like a can of change rattling around. (this thread discusses the same noise, but my heat shields and fan clutch seem solid, and my video below really sounds like it's something piston relatated)



Thoughts?
 
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I think is vacuum related. It sounds like a diaphragm piston cycling. Just as the throttle opens but before the fuel system kicks in to add fuel and boost revs it pops.
It should be supper easy to find with a long bladed screw driver (to keep you out of the spinny bits), touch the tip to a component and touch your ear to the handle and have someone goose the throttle. You're playing Hot and Cold around the engine bay, when you touch the right component, you'll know it.

It also sounds like an AC clutch, I'd look at that first and see if its cycling in and out of engagement with throttle taps.
 
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Somebodyelse5

Land Crushers
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Feb 9, 2014
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Phx, Arizona
 
Thanks for everyones replies and patience. Ignition systems are still black magic, so i am learning. If you have any good resources I am happy to do some reading.

I think is vacuum related. It sounds like a diaphragm piston cycling. Just as the throttle opens but before the fuel system kicks in to add fuel and boost revs it pops.
It should be supper easy to find with a long bladed screw driver (to keep you out of the spinny bits), touch the tip to a component and touch your ear to the handle and have someone goose the throttle. You're playing Hot and Cold around the engine bay, when you touch the right component, you'll know it.

It also sounds like an AC clutch, I'd look at that first and see if its cycling in and out of engagement with throttle taps.
Awesome, I will give this a look. Is there actually a diaphragm piston that I can look at (the vacuum system on these is a mystery to me)?

I've put a vacuum gauge on and (although I forget the number) it was holding. My brakes are tough to push so I've been chasing that a while (new check valve, new vacuum hoses) I have been chalking it up to the aftermarket booster the PO put on.

I also enjoy that you called them "spinny bits" :rofl:

I hear preignition ping. Just like mine.
Is that what you're hearing?
I think so, I'm pretty inexperienced when it comes to engine diagnostics. So, let's call it pinging... is there anything specific to the 1FZ that I should know about, as it relates to pinging? I'm doing some reading and it seems that pinging is pre detonation, due to hotspots/carbon buildup. I'll try running some higher octance next fill up and see how it changes, but if it's carbon buildup will this help?

Would pinging be impacted by engine temp? Hotter = more pinging? (it's been in the 100's here and the noise is significantly more noticable)
 
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Something easy to check would be your timing. But I would think if your engine is pinging then the knock sensors would be picking it up and retarding your timing to stop it. Poking around with a long screwdriver or mechanic stethoscope as Rusty says should be able to pinpoint it too. Checking the AC clutch should be easy. Does it do it with the AC and defrost off?
 

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