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

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Somebodyelse5

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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?
 
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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I think I hear pinging too. Definitely heard it in the first video. Try higher octane gas.
 
I'm with Rusty
 
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)
 
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?
 
I'm still interesting

it’s incredibly heat dependent. My current theory is carbon build up retaining heat and causing pre ignition. I picked up a bore scope to have a peak in the cylinders
 
update:

I managed to solve the problem after suspecting it was pre detonation due to carbon build up in the cylinders....

  • Ran a full can of MOPAR Combustion Chamber Cleaner (MCCC), with the engine running (and someone helping to keep the engine running). I disconnected the PCV hose from the valve cover and alternated spraying the MCCC and plugging the hose with my thumb. Your rpms will drop suddenly and the engine will want to die if you leave the hose unplugged too long. Followed the instructions on the can... warm up, spray in full can, run for another 10 minutes. This stuff does not smoke nearly as much as Seafoam does
  • I removed all the spark plugs, looked like they had a bit of carbon fouling, most of them measured ~.040" gap (one was at ~.025")
  • I sprayed most of another can of MCCC into each of the cylinders, put the plugs back in loose, and let it soak the head of the cylinders for 24 hours
  • I rigged up a small hose attachment for my shop vac and sucked out all the schmoo, looked like cookies and cream coming through
  • I sprayed carb cleaner and let that soak for about an hour and then spent a long time spraying and using the shop vac until what was coming out was relatively clean
  • New plugs gapped to .031", new ignition cables, and new distributor cap
  • Started up, got to temp, and let the crud burn off (not nearly as Smokey as you'd expect)
  • I then checked the timing with a timing light per FSM (it was about 15deg BTDC.. which is WAY too advanced). I bumped it back to 3* here is an OTRAMM Video:
  • Definitely should change your oil after you do this

After that, I'd say the issue is 95% solved. Does it a tiny bit if I rev it up from idle, in neutral, but not nearly as bad as in my video. I'm attributing that to the carbon that still remains in the cylinders.

Here are some pictures, as best as I could get using my cheapo bore scope.

After one can of MCCC:
View attachment 2582833
View attachment 2582834View attachment 2582835View attachment 2582836

Cylinder after 24 hours of soak (I was unable to get clear pictures after the carb cleaner went in, no matter how much time I spent with the vacuum):
View attachment 2582837
 
Another of of a different cylinder:

20210210180638.JPG


Spark plug #6 (they all looked similar)
IMG_3321.jpg


Vacuum attachment:
IMG_3333.jpg

And in use:
IMG_3335.jpg
 
Hey, my truck is making a noise, what snake oil can I pour in it to fix it?

Never works.

Hope you didn't screw up your cats pouring that crap in it.

It was timing. You can hear the preignition at every rev. Timing should have been the FIRST thing you checked.

Hopefully you used the paperclip bypass and followed the FSM to get it to set and hold properly.

Why would the PO set the timing that high unless they too had no idea what they were doing.

You want to get rid of "carbon build up"?

DRIVE IT! Long sustained distances will burn the crap out and do wonders.
 
Hey, my truck is making a noise, what snake oil can I pour in it to fix it?

Never works.

Hope you didn't screw up your cats pouring that crap in it.

It was timing. You can hear the preignition at every rev. Timing should have been the FIRST thing you checked.

Hopefully you used the paperclip bypass and followed the FSM to get it to set and hold properly.

Why would the PO set the timing that high unless they too had no idea what they were doing.

You want to get rid of "carbon build up"?

DRIVE IT! Long sustained distances will burn the crap out and do wonders.
Would have been cool if everyone suggested checking the timing first :rofl: none of the discussion here or other threads suggested timing. And idk that much about engines, this has been a big learning process for me.

I learned, hopefully someone see’s this and tries checking their timing first.

and yup, used the paper clip. Linked Otramms video with instructions to hopefully help who ever comes across this down the road.
 
Would have been cool if everyone suggested checking the timing first :rofl: none of the discussion here or other threads suggested timing. And idk that much about engines, this has been a big learning process for me.

I learned, hopefully someone see’s this and tries checking their timing first.

and yup, used the paper clip. Linked Otramms video with instructions to hopefully help who ever comes across this down the road.
Post #4 stated preignition. That's typically timing.

Sorry, not bagging on you. The intent is so other newbs such as yourself don't think the first step is to pour crap in it.

I understand you're trying to learn and it's hard to sort through all the BS to get the real information because there are a ton of threads out there that someone poured something into an orifice and it magically fixed itself.

Some of us that have done a lot of real diagnosing and real troubleshooting (NOT just plugging it into a computer to tell you what sensor to change next) can walk through this stuff because we learned it the hard way. There were no computers or OBD systems to tell us where to start.

We're typically salty old dogs and we bark a lot.
Just listen and nod your head.

Then get off our lawn.

Sorry I missed your original post back in May.
 
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