Rattle from engine when accelerating (sounds like keys)

[DAVECS1]

for sure, but the problem is that between 1,200 rpm and 1,800 rpm is where the best gas mileage is. I'm getting fantastic mileage for what this thing is, and i'd really love to eliminate the knock.

That's probably the engineers' problem. tuning for max economy is probably similar to tuning for max power. You're running on the ragged edge

Oh your on point, for sure, they are one and the same. In order to use my supercharger at cruise I had to make significant cam timing changes. They try to keep the valves closed at low rpm, stock. The problem is at high load it helps to have scavenging and exhaust flow to cool the cylinder. The factory does not do this at low aircharges. This causes issues more so on manuals as it can run a considerable amount of time here. This causes high vacuum that sucks oil from the sump, it causes high heat and high pressures in the cylinder as there is a fair amount of time to fill the cylinder with stuff that goes bang. So if cam timing never gets changed stock you options are limited to time tested solutions, high octane good oil, and decent crank case venting

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[Scrubb84]

Yes that's right, but that vacuum is going to take the path of least resistance between the two, and the least resistance is going to be the closer one and clearer one, which would be the filler neck. I just threw out random numbers that it might be a 67% filler neck 33% valve cover split. In that case, 100% coming from the valve cover before gets reduced to 33% after. So that's where the benefit is.

the reason the teraflex product would work is because when the pcv line is full of oil, the intake manifold vacuum will take the path of least resistance - the filler neck. In that case, it will be 0% valve cover and 100% filler neck and the intake manifold won't get flooded with oil, making the smoke. But i bet during normal street operation, it will have a benefit that significantly less oil will be pulled from the valve cover

I been thinking about this for a bit. What would be the reason for keeping the stock pcv then? Did they simply not want to make a plug for it?

 

[Jeepin' John]

So far so good here. 89 / 5w-30 / mishimoto. 18.5 mpg city/suburb (no highway) on 33's / 3.73's. Rare light LSPI - dramatically reduced from previous

i just re-routed my "dirty" catch can line. I noticed that it had a "trap" behind the engine where the line dipped down and then came back up to the can. Not sure if that makes a difference, but a trap in the line can't be a good thing. I routed it higher so that the line goes up from the pcv valve, peaks at the coolant tank, and then comes down to the catch can

Update: so while LSPI knock was reduced, it wasn't eliminated completely, and the 5w-30 viscosity oil was still blowing through the mishimoto to some degree. So today i drained the 5w-30 and went back to 0w-20. I'm not going to run a different viscosity oil unless the knock was completely gone.

my next step is to pair the teraflex crankcase ventilation system with the mishimoto to try and eliminate oil getting into the intake manifold. I'll let you guys know how that goes. If that doesn't work, it will be either to modify the mishimoto or to possibly replace it with a different can with more extensive baffling. Looking at the mishimoto, it's a bit basic and simple, which i like, but to the degree that it's actually effective. The location is perfect / clean. I just wonder if more baffling is necessary to prevent oil making its way through

 

[SelfmodJT]

What rattle? It all goes away on a night like this.

 

[Renegade]

I would like to be able to differentiate between engine noise and transmission noise. Mine definitely clatters during the shift. I was wondering whether the ignition timing gets retarded during shifts, causing the clatter. Alternately, I’ve wondered if it actually coming from the transmission.

 

[Higher_Ground]

Mine did sort of sound like it was coming from the area of the transmission, but I just assumed that's where the sound was finding it's way out. Sort of like hearing sirens in a downtown area and the noise bounces off buildings.

At first I thought it was doing it when shifting too - but I have heard it more consistently when the transmission stays in too high of a gear while the vehicle decelerates, then lugs as you attempt to accelerate again. The typical case for me was speed humps on a 25 mph road: speed up to 25 mph (~4th gear), decelerate with little or no braking to ~15 mph (still in 4th, sometimes in 3rd) and then accelerate with ~0.5-1.0s of pinging before I got the RPMS up to speed or the truck decided to shift.

 

[Scrubb84]

I would like to be able to differentiate between engine noise and transmission noise. Mine definitely clatters during the shift. I was wondering whether the ignition timing gets retarded during shifts, causing the clatter. Alternately, I’ve wondered if it actually coming from the transmission.

Does it hesitate or lose power when it happens during shifts like mine? Just curious

 

[GuamJT]

I had this issue, The heat sheild near the loop in driverside exhaust bank was the issue (For me). But it drove me crazy and it took me riding with a tech to show what I was talking about.

They had to put the truck on a lift with a driver in the seat and do some accelleration runs to get it figured out.

Thanks for this! Ended up being the same issue on mine and I would’ve never checked there if not for your post.

 

[Renegade]

Does it hesitate or lose power when it happens during shifts like mine? Just curious

No loss of power.

 

[Scrubb84]

Anyone figure out this rattling 100% yet? I got a few more ideas, but it’s gonna have to wait till spring time.

 

[shokker70]

Anyone figure out this rattling 100% yet? I got a few more ideas, but it’s gonna have to wait till spring time.

I think part of the problem is there are multiple sounds being lumped into one category. Mine didn't affect performance or anything else, so I just lived with it. Actually just traded my Sport S for a Mojave. I'm anxious to see if it's there on this one.

 

[ShadowsPapa]

I think part of the problem is there are multiple sounds being lumped into one category. Mine didn't affect performance or anything else, so I just lived with it. Actually just traded my Sport S for a Mojave. I'm anxious to see if it's there on this one.

Yuuuup - any rattle sound is being called ping/detonation when in reality there are multiple reasons for similar sounds, even multiple reasons for true engine ping.
But it's all been condensed into a single thing - I see it a lot on the web - "anyone have a fix for this" when there are many different causes, or they aren't really hearing what they THINK they are hearing (or seeing)
The internet has really ruined troubleshooting and tossed diagnosing to the curb with the trash.
And no one gives any detail, exact conditions, just "my truck makes a sound when I accelerate" - no mention of transmission type, road speed, engine RPM, throttle position, load, up a hill or on the level, air temperature, whatever.

I've tried to FORCE mine to rattle and I can't make it ping.

 

[Scrubb84]

Yuuuup - any rattle sound is being called ping/detonation when in reality there are multiple reasons for similar sounds, even multiple reasons for true engine ping.
But it's all been condensed into a single thing - I see it a lot on the web - "anyone have a fix for this" when there are many different causes, or they aren't really hearing what they THINK they are hearing (or seeing)
The internet has really ruined troubleshooting and tossed diagnosing to the curb with the trash.
And no one gives any detail, exact conditions, just "my truck makes a sound when I accelerate" - no mention of transmission type, road speed, engine RPM, throttle position, load, up a hill or on the level, air temperature, whatever.

I've tried to FORCE mine to rattle and I can't make it ping.

Very true. The temp is a huge factor with mine. Just bought a steelman chassis ear so I can finally figure this out, but it might have to wait till spring because its so cold where im at. And i dont have a garage.

 

[bwm2020]

well noise has gotten worse and this summer had a different dealer check it and they said it was normal and pre-detonation is the reason. Yeah, really don't think so.

 

[ShadowsPapa]

well noise has gotten worse and this summer had a different dealer check it and they said it was normal and pre-detonation is the reason. Yeah, really don't think so.

And the dealer said or used the word "pre-detonation" ?
There's no such term.............. I guess dealers don't know the difference between pre-ignition and detonation. They can't fix what they can't even describe.
No wonder people are having issues.
First they have to understand what each is, then what causes each one, before they can do anything.
A certain amount of ping from detonation is not unexpected but it should be barely audible, not "loud".

I can't even FORCE mine to ping or detonate. I've tried both of our Jeeps (both have 3.6) and nope, not a sound. Even going up a fair hill, accelerating with it in the lower RPM range, or holding the brake and giving it gas while in gear as if to do "a brake stand" - no ping.

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