Ticking/Rattling sound at low RPM under acceleration

There is a relatively subtle ticking sound present at low RPM (<2000 RPM), under load, in any gear, and at any vehicle speed. I don't hear any ticking when the engine is still cold, or when the RPM increases above ~2000 RPM. I also cannot hear the sound when the car is in neutral, and I hold low RPM; it is only happens when I am in gear and accelerating. It definitely doesn't sound like an engine knock, more like a plastic bead rattling around inside a metal can. I embedded a video that has a similar sound, but my sound is a bit more erratic.

From the research I have done, it is likely to be a valve train issue or an exhaust leak. In regards to the valve train, I replaced my oil and oil filter, and still hear the noise. Also, I would expect that if the issue was in the valve train, I would hear the noise even when the engine was idling, which I don't. In regards to an exhaust leak, I haven't checked the bolts on the exhaust manifold yet because they're a bit hard to get to. But I am not sure this is the issue, because from what I understand, exhaust leaks are more severe when the engine is cold and tend to lessen once the engine/exhaust heats up, and in my case the opposite is happening.

Has anyone else had this issue, or maybe has some insights as to what the source of the ticking could be?

Thanks!

I should also mention that truck has ~230,000 miles.

EDIT: This video is not mine, it is some random video I found on youtube that had a similar sound to my truck.

 

I usually use 85 octane (I live at ~5k ft), but I tried putting in some 91 to see if that helped, and it does. With higher octane fuel I can't really notice a sound at all. So the problem seems to be related to preignition, but I'm still not sure what the cause is, and I'd prefer to not keep paying a 20% premium for fuel. Any ideas for what the problem could be that don't require too much disassembly of the engine to check?

 

The injectors can be pretty loud- so I'd lean towards those.

You can sea foam or smoke test the exhaust to look for a leak there.. But at 230, if you haven't touched the injectors.. They'd be my first guess.

You can either pull yours out and have them cleaned and serviced, or get some new ones. The OEM ones are expensive. MotorWest sells an "upgrade" denso set that are used by and highly recommended by many here (myself included).

Edit- and for whatever it's worth, I only run 91- nothing but the good shit for my truck

 

Thanks for the suggestions Andy. I don't know when the injectors were last serviced or replaced, but there is a gas smell coming from my engine bay that is strongest right after I shut off the engine. I always thought it was related to my EVAP system having a leak, but maybe that is another symptom of bad injectors. Those injectors from MotorWest look good, I guess I'll have to look into how one replaces these things now :/

 

A bad exhaust manifold gasket, cracked manifold or loose manifold(or crossover pipe) will make a sounds like that. Cold or hot you tend to hear them when there is some pressure on the engine.

 

https://youtu.be/irFXP4pAf6E

they sell 85 octane in the mountains.
don’t use that at sea level or lower elevations. It meant to be used up at elevation. Even then it isn’t good for newer things that are not carb.

 

If this was the problem, how would you explain the fact that when I use premium gas the sound essentially disappears?

And I live around 5-6k ft, well within the range where 85 octane is acceptable. If anything I only go higher in elevation, not lower.

 

Well then you may have multiple issues.

Here is an excellent video on replacing the fuel injectors:
https://youtu.be/N-lhZIWOkyU

In this video (as per the FSM) it suggests using gas as a lubricant when installing the injectors and fuel rails. I found that using a tiny dab of the supplied (with the motor west injectors) super lube on the o rings to be a less error prone approach. When I tried the gas method I ended up pinching a few of the o rings which resulted in a fuel leak and having to tear everything apart again.

I don't think the injectors would cause an fuel smell in your engine bay. I'd be looking for an exhaust leak or evap leak. Sounds like a smoke test is in your future.

 

Andy: Thanks for linking that, I was actually just watching that video this morning; it doesn't look too bad.

I thought maybe the injectors might have bad o-rings that lead to a leak, but it's probably my evap system. I have been throwing a P0446 for a while now I just haven't bothered to fix it.

It's also maybe worth mentioning that that evap code is the only code my engine throws, I don't get any misfire codes or anything like that.

 

85 octane is perfectly good for that elevation. Using anything higher does nothing but waste money. I run 85 octane in mine at 4500ft.

as to the problem at hand, when’s the last time you did a good tune up? New plugs, wires etc. When I first got my 3rz Tacoma i had something similar happening it was pinging under hard loads like cruising up hill etc. and for some reason a new set of plugs fixed it.

 

Brandon: I'm not sure, I've owned the car for 2 years/20k miles. But I am picking up some new plugs right now actually, and I'll probably check compression while I'm there just for shits. I figure I should replace plugs before I commit to replacing the injectors.

 

Probably because its a ford? Haha.
I thought you were talkin about the sound In Your video which sounds like the manifold is leaking. But 85 will make your truck knock being its not carbed or tuned to run on 85 even at elevation. But I didn’t hear that In your video.

 

Oh lol, I just included that video because it sounded similar. But yeah it doesn't sound like a knock to me either.

 

This is fake news. 85 octane has nothing to do with being carbureted and will work perfectly fine in these trucks at higher elevation unless they are supercharged.

 

https://youtu.be/kJyd6C99_3g


fake news haha. Did you have a source of information. I’d like to see. This guys source is well aged.

 

These trucks should run on lower octane just fine normally, but if the sound goes away with higher octane fuel then you might have an issue with pinging. How many miles are on your spark plugs?

I have a supercharged 3.4l and thus I need to run 91 octane minimum or else I get heavy pinging under load/boost. Sounds like marbles rattling in a can. It's that what you're hearing?

 

the source is years of experience and understanding how engines work and what octane rating is and does. It’s not new science and has been well understood for probably a century now, well before people started making YouTube videos. Octane rating is resistance to detonation. The characteristics that cause detonation are the same in an engine that is carbureted or fuel injected. Typically has to do with compression and timing, although other things can be a factor as well. The more compression or timing you have the more chance you have for pre-ignition or detonation this the higher octane you need to prevent that from happening. Forced induction, or even lower elevation to an extent, essentially raises the compression thus requiring higher octane. Just as going up in elevation where the air is less dense basically lowers compression thus lowering the octane requirements. So a car that is designed to run on 87 octane at sea level(as most vehicles are) is perfectly fine on 85 octane at elevation. There is a reason they sell 85 octane gas in the higher areas of the country and stop at 87 at sea level and it is not because gas companies are trying to blow up your car. This also means, contrary to popular internet belief, there is zero, zilch, nada single benefit to running 91 or higher octane in an engine that is designed to run on 87. It’s just a waste of money.

 

Ryan it sounds just like marbles in a can, it's somewhat rhythmic but still kind of erratic too. The plugs have at least 20k on them, that's as long as I've owned the truck. But I'm replacing them today so I can update later.

Also, this discussion of octane is getting pretty off topic I think. If people want to play it safe with higher octane, more power to you, but I don't believe it is necessary at my altitude. I only put in 91 to try to debug this issue.

 

I apologize for derailing your thread. There’s just so much false info and myths on the interwebs these days that I have a tendency to try to correct them for the greater good. I’ll move on, good luck with your truck.

 

No worries, and I hear ya, especially since this notion of higher octane = better is so persistent. But what can you do.