Can a VVT-i problem sound like an engine knock?

Mehh, I like the Briggs and Stratton philosophy. Just top it off. It never needs changed.

Seriously, that’s a real thing.
https://www.briggsandstratton.com/na/en_us/campaigns/just-check-and-add/true-value.html

 

Honestly many lawnmowers never get the oil changed anyway
But seriously that's nuts
Maybe they don't expect it to last long enough to need an oil change

 

That'd be too easy.

 

It sounds like I'd be seeing a code if VVT-i was the real culprit?

 

Whatever is causing this sound, is getting worse. It's more and more frequent.

 

Update:

The noise got worse today.

The best way I can describe it is someone shaking a rattle can spray paint bottle under the hood as you're revving up through the lower gears.

I'm stumped.

 

Sounds like the classic description of detonation to me.
I’m not saying it is, but your description is fitting.

Have you had any with experience in hearing detonation have a ride with you?

@Dm93 is it possible to see live timing data on a scan tool?
Be interesting to see if the truck try’s to pull timing when this happens?

 

I'm running 93 octane fuel. How could I be knocking at 93?

Thanks.

 

Your first post indicates you may have a tune?
You say you have a log file. There are guys on this forum that tune.
One might look at it for you?

Octane alone doesn’t prevent detonation.

 

Yes with a scan tool that can read manufacturer enhanced data or HPTuners you can view timing and knock values in realtime.

I'm wondering if it isn't a catalytic converter that is coming apart maybe, have you banged on all the exhaust components with it cool and listened for rattling?

Only other thing I can think of is an internal engine problem or a knock sensor that isn't working properly although I would expect it to flag a code unless the tune has those codes disabled which would also be odd.

 

Take a look at your tensioner and idler pulleys. Had one going out and had a similar rattle that came and went. I thought the worst and was pleased that it wasn't serious.

 

Are you running any kind of forced induction (turbo, supercharge)? If not, then there really is no benefit to running 93. In fact, lower octane might run better. High octane fuel is better for high compression engines, it doesn't denotate as quickly and therefor won't get pre-detonation issues. Lower octane fuel actually burns better, but can sometime denotate too early in high compression engines, hence the need for higher octane.

Higher octane also does not mean cleaner burning anymore. Any additives found in high octane exist in the lower grades as well.

FWIW, I had a similar sound to what you are describing. I used to run 93 octane exclusively until this was explained to me. I switched to 87 and right away my knock sounds disappeared. Strange, I know. But I think the problem was late detonation with the higher octane.

 

I too am having the exact problem at the op.
2015 tacoma 4.0 with a tune. It is a fast rattle noise around 2000 rpm till it shifts. Went for a drive with the tuner he logged and no signs of spark knock. The only thing we could think of was the vvt. Have you had it resolved? Just ordered now vvt solenoids and screens hoping to get them in soon.

 

Any luck with ur issues? I'm having the same exact problem as u.

 

In the end, it turned out to be my tune. OTT adjusted it and the problem immediately went away.

 

Interesting, I had them data log it and they didn't seem to be worried about it. You know what they had to adjust? This noise is driving me crazy.

 

I asked them specifically what they changed but they did not tell me. I don't think they wanted to give that away.

As far as problems in general go, if you email them, they are good to work with.

I would try to work the issue. I know that with the level of noise I was having, there's no way the engine would have lasted. Something would have had a hole burnt through it eventually. It was "knocking with a purpose".

ETA:

I told them that I reverted to the stock tune and the problem went away. At that point, they really dug into it and came up with a fix that I am running to this day.

 

Same thing here, OTT tuned 2011 4.0 255k. Rattles like the valves are gonna fall out around 2000 RPM just before shift. This has been driving me crazy for around 6,000 miles. First thing I thought was the timing chain has stretched and I'm gonna have to tear the whole motor apart. Then I checked the breather hoses and found blow-by gunk all around the outlet on the passenger valve cover and oil in the intake at the other end of that hose just before the throttle body so I changed the PCV valve but still getting the rattle. I was about to order some cheapo Oil Control Valve (vvt solenoid) from rockauto and try that but figured I'd check TW one more time first.

OP, it sounds like your tuner figured out how to compensate for it in the tune file. I'm going to get in contact with my tuner and see if he's aware of the issue. He's a good guy with stellar support so I doubt I'll have any issues. I'm glad you finally found a solution.

 

I am glad this thread is still alive.

I'm now hearing another noise and am wondering if it's VVT-i-related.

Is there a way to disable VVT-i? A fuse, perhaps?

Thanks.

 

Unplug the oil control valves.