Rattle from engine when accelerating (sounds like keys)

[Jeepin' John]

Would you even need a catch can if the pcv valve was in a better spot from the factory? Mite be a dumb question, but isn’t it located in pretty much the worst spot possible? Back of the engine and behind the valve cover (not on top of it). Mine as well put it on the flippin oil pan. Lol

you might be on to another factor. I don't drive my wife's pacifica much at all, but i don't think i've heard hers knock. I might need to drive hers around with windows down and see if i can get it to.

I'll check later, but the pacifica pentastar is probably level (since it's transverse), so the pcv pick up might be physically higher than on the JT, where the engine is angled, sloping down to the rear where the pcv pick up is. Not sure if that makes a difference or not, but maybe it's a contributing factor

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[Jeepin' John]

And i can't wait for this to come out

https://teraflex.com/2021/07/02/jl-jt-3-6l-crankcase-vent-system-cvs-teraflex-new-product-video/

My thought is that by pulling from 2 points, flow will be reduced - probably more flow 67% maybe from the oil filler neck (cleaner) and 33% behind the valve cover (dirtier). I don't see how any oil could get to the intake manifold if this is paired with a catch can

 

[ShadowsPapa]

I don't know why they don't pull all crankcase venting from the oil fill tube - get it up and away from moving parts that mix the oil into the air.
In the old days, that's where the air went IN to the crankcase so it had to be pulled from an area away from the incoming air to properly vent vapors.
Quite a few engines had the PCV venting out the top of the valve cover after passing through a couple of mazes and baffles.
Some had serious trouble when the PCV pulled from the valley area between the heads, under the intake. There's a whole lot of oil being tossed about by the cam and other parts up there and a lot of oil got pulled up into the intake when it was vented in the oil fill and out the valley pan area.
With an overhead cam situation (4 of 'em, no less) it would seem a lot of oil would be flung from those spinning cams and mixed into the air in the "Valve cover" area on these.

 

[Scrubb84]

And i can't wait for this to come out

https://teraflex.com/2021/07/02/jl-jt-3-6l-crankcase-vent-system-cvs-teraflex-new-product-video/

My thought is that by pulling from 2 points, flow will be reduced - probably more flow 67% maybe from the oil filler neck (cleaner) and 33% behind the valve cover (dirtier). I don't see how any oil could get to the intake manifold if this is paired with a catch can

Please correct me if I’m wrong....
If oil is being sucked in threw the pcv (which it is), and u add a second vent up top at the filler neck, wouldn’t it still suck oil threw the factory pcv that is still there???

 

[Jeepin' John]

Please correct me if I’m wrong....
If oil is being sucked in threw the pcv (which it is), and u add a second vent up top at the filler neck, wouldn’t it still suck oil threw the factory pcv that is still there???

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

 

[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

Thanks for explaining that. Now I can’t wait to get the set-up when it’s available. ??

 

[DAVECS1]

The cam timing is too aggressive for all plausible operating conditions in conjunction with elevated timing and a fuel map that does everything and a bag of chips to stay at stoich. Add to that a manual trans and guys who like to run it below 2K most the the time. Itis going to happenand some are worse because the phaser is slow. My cam timing after being on the dyno looks like it is from another planet. Octane booster is a serious long shot and you would need two or more tanks for it to really make a difference.

 

[ShadowsPapa]

The cam timing is too aggressive for all plausible operating conditions in conjunction with elevated timing and a fuel map that does everything and a bag of chips to stay at stoich. Add to that a manual trans and guys who like to run it below 2K most the the time. Itis going to happenand some are worse because the phaser is slow. My cam timing after being on the dyno looks like it is from another planet. Octane booster is a serious long shot and you would need two or more tanks for it to really make a difference.

THANK YOU for your scientific input. So I wasn't crazy suggesting that "octane booster" wasn't going to make a difference that quickly - especially drop it in and take it for a drive.
I'm thoroughly impressed that they can keep this thing in stoich so often.
You've seen me gripe about the low RPM bands on these things. Give me sub-2000 on the highway but below 50 mph, give me 2,000+
If mine was a stick, I'd be winding this thing up far tighter than the transmission programming does on these automatics. I'd likely hit 2500-3,000 rpm before shifting and not let it go much under 2,000 until I hit the highway.
But like I said - mine just doesn't ping.

MY opinion, my thinking -
Keep the RPM up on these, folks - stop babying it.

BTW - I hope that bag of chips is either dill pickle or jalapeno flavored.

 

[SelfmodJT]

THANK YOU for your scientific input. So I wasn't crazy suggesting that "octane booster" wasn't going to make a difference that quickly - especially drop it in and take it for a drive.
I'm thoroughly impressed that they can keep this thing in stoich so often.
You've seen me gripe about the low RPM bands on these things. Give me sub-2000 on the highway but below 50 mph, give me 2,000+
If mine was a stick, I'd be winding this thing up far tighter than the transmission programming does on these automatics. I'd likely hit 2500-3,000 rpm before shifting and not let it go much under 2,000 until I hit the highway.
But like I said - mine just doesn't ping.

MY opinion, my thinking -
Keep the RPM up on these, folks - stop babying it.

BTW - I hope that bag of chips is either dill pickle or jalapeno flavored.

Pings in the 2000 to 3000 range, doesnt matter if you shift between 2500 to 3000. You would have to keep it between 3000 to 4000 rpm range .

 

[DAVECS1]

The wranglers and Gladiators are really setup to use all the rpm and then some. If ypu have low grade oil and low grade fuel and then lug the engine all the time, your gonna get ignition noise. If you use 89 or higher and a good synthetic changed regularly, and let it rev out to 3k or better, welcome to the nice sounding engine jeep club.

 

[ShadowsPapa]

The wranglers and Gladiators are really setup to use all the rpm and then some. If ypu have low grade oil and low grade fuel and then lug the engine all the time, your gonna get ignition noise. If you use 89 or higher and a good synthetic changed regularly, and let it rev out to 3k or better, welcome to the nice sounding engine jeep club.

After my towing trip - I realized just how much better these do with some RPM. I let it wind up on the hills and the more I let it, the less it seemed to need to. It really shone 2200-3300 or so (rough numbers) and when it hit over 4,000 on a couple of the first hills, I just let 'er go.

 

[Jeepin' John]

The wranglers and Gladiators are really setup to use all the rpm and then some. If ypu have low grade oil and low grade fuel and then lug the engine all the time, your gonna get ignition noise. If you use 89 or higher and a good synthetic changed regularly, and let it rev out to 3k or better, welcome to the nice sounding engine jeep club.

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

 

[ShadowsPapa]

Any engine is most likely to ping at those RPM. High load and very high combustion pressures = heat, plus, detonation takes TIME. There's plenty of time at that low RPM. Higher RPM, the final bit of charge is burned before it can self-ignite.
All of that is true with any engine.
That low RPM is well outside of the better torque and HP, and it's where you have extreme loads causing high heat and pressure.
In other words - good luck.

 

[DPF140]

If you have a GoPro or similar camera, you could move it around in the engine bay until you find the area the sound is the loudest. I considered doing that on another car that I was having suspension noises on, but figured it out before I had to take that step. Just a thought…

 

[ShadowsPapa]

If you have a GoPro or similar camera, you could move it around in the engine bay until you find the area the sound is the loudest. I considered doing that on another car that I was having suspension noises on, but figured it out before I had to take that step. Just a thought…

That's a good idea because those RPMs and conditions are also where you have the most vibrations and rattles anyway.
The engine normally "Vibrates" more under those low RPM stresses so someone could catch a "rattle" that isn't actually ping.

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