Noisy 4L. engine

Hi everyone.

My 4.0 L. engine makes a strange noise some kind of clicking or slamming like too
much clearance on valves and that can't be that 'cause there is no adjustment on
this engine.Somewhere in your forum you were talking about the evap (purge) valve
on the left side of the engine and i replaced it but the problem still exist .I even tie
the valve on other hose instead of fixing it on the engine head like you said and the
noise is stille there.

Any idea ?

 

Any recordings of the sound? Could be the (in)famous taco tick, which is fairly normal. If so, long as you don't see any glitter in your oil you shouldn't have anything to worry about.

 

Post a video on youtube and post the link here.

The 4.0L is inherently noisy, just for reference here's mine.
https://www.youtube.com/shorts/qyv-iJjt8yk

 

Sounds very similar to mine at idle. (+- 134.000 on it now and hasn't changed since I bought it @104k.) I will say it also idles very smooth: no discernible shake at all. Not quite as smoothly as the V8's I have had, but that's to be expected. In "D" at idle you can't really feel it in the truck at all which is impressive.

 

Late to the party on replying here. One thing I have noticed is when you dump top tier gasoline in these engines, they quiet down severely. I used to get fuel for mine at a station close to the house. Never Again!!!!!! Mine was so bad, sounded like it had a knock. But i knew it wasnt. I always run Shell 93 during the summer to get most output of the engine since i tow a 6x12 enclosed trailer. i mow for a living. But as long as you just use it as a regular daily, dump shell, exxon mobile, marathon, or any good top tier 87 in it and i promise you, you will notice a differance. Mine has significantly quieted down. Ill post a youtube video of mine and post it in here. sounds crazy, but the results in my case spoke for itself.

 

https://youtube.com/shorts/iQIjX0eNOXY?feature=share Video can be viewed tomorrow. These engines are a dinosaur. However, Extremely picky if you want them to run extremely sound.

 

In the summer with hot temps, (90+) in traffic, mine will ping slightly on initial acceleration in stop and go traffic. Supposedly there was a TSB for this very issue back in the day. It involved a re-flash of the ECU to address it. Pretty certain mine never had it done. Top Tier (per labels on the pump) Phillips-66 or Shell 87 gas gets rid of the pinging on my truck. Interestingly, Mobil does not unless you give it 89.

 

Interesting. I know running shell 93 when towing 2900lbs, builds torque much easier and doesn't ping near as much

 

I have always heard that some modern-day engines can adjust themselves for higher octane gas when you put it in. No idea or explanation how they actually accomplish this though. I can hear/see how they adjust to crappy no-name 87 octane gas on my particular truck: likely knock and ping sensors..... but how do they seemingly adjust the performance on higher octane fuel? I have experienced it (see previous) but I have never seen it explained anywhere that sounded any better than just snake-oil gibberish. YMMV

 

From personal experience, towing 2,900lbs. My engine getting going, ot felt like to me it struggled to build torque compared to running premium. It doesn't feel like it's straining near as much.

 

Agree here. It seems there is a performance difference you can hear and feel. But the venerable 4.0L still has that "clackety-clack" sound, especially at idle, that to be honest: I actually like.

It sounds like an engine that belongs in a truck. Just like the A750: it shifts and complains and acts up a little on forced downshifts when it really doesn't want to/like it: just like an old crabby person and again: "like a transmission that belongs in a truck" and I happily tolerate it, because: just like the 4.0L solid lifter: unless you abuse it: it never breaks down."

Honorable mention: the vintage

$90 2005-2015 Toyota Tacoma With 4L Right Petrol intake air snorkel kit high performance system compatible kit Replacement black Rotational Molding (2005-2015)

2005-2015 2nd gen 4x4 electronic ""don't ignore me for years" system: Same thing: "Turn the dial once in a while Gomer, or its going going to cost you... Diagnostic codes??: lol...."Here is a ZipLoc bag filled with jumper wires: figure it out yourself". Love it.

 

Hilarious. But yeah, I've noticed bigtime differences when it's super hot and when your using it as a work truck

 

Here is the TSB I referenced previous.

https://static.nhtsa.gov/odi/tsbs/2014/SB-10061330-2273.pdf

 

Yeah, mines a 15. But that's why I didn't worry about it. Supposedly I heard its supposed to have the latest flash. It's still not the best on 87 when your using it as a work truck

 

The valves are adjustable, you just need to measure and replace the shims with the correct size to adjust.

 

If it isn't clattering, it's too tight.

 

Makes sense that the 15's would have had it as built. I chuckled at the under-hood sticker info: no sign that there was ever a sticker like this on my truck. My truck is ten years in now. I figured I would pass on this thinking that if an update like this ended up bricking the ECU, that it's unlikely Toyota would spring for the cost of making it all good. Ya: Not likely.

 

Modern engines can / do actively adjust for fuel octane level with a pretty basic mechanism, a feedback loop between the knock sensor & the ECU's commanded timing advance/retard.

I believe the way it works is the ECU adjusts the engine timing until the threshold of knocking (which varies according to fuel octane level,) and then adjusts timing back out of the knock zone into a safe margin of no-knock. Not sure how fast this feedback loop operates. I'd bet it's on the order of a couple of crankshaft revolutions.

 

To my knowledge Toyota does active timing control using the knock sensors sort of like how fuel control on any fuel injected engine works, you have a base timing map and a short term correction value and a long term correction value based on the feeedback from the knock sensors.

@JustDSM may be able to explain it better but that's how I understand it.

 

That's not wrong at all, and that is how I generally explain things to curious individuals. It's obviously much more complex than that, but that is the 30,000-foot view of how the system works.

We were specifically asked about this on the 4Runner side and did separate 91/87 octane dyno tests to show how our calibration is affected by non-premium fuels while demonstrating how the same file can adjust to this change and maintain the built in safety margins Toyota engineered into their powertrains. It absolutely works. The differences are relatively minor in the big picture but they are measurable.