Car Gurus: Today's Timing Systems?

I have a 2014 Honda CR-V with an engine error code indicating the timing is out of synch. After talking to my mechanic for as long as he could spare and reading info online, it appears there could be a stretched timing chain, a faulty tensioner, and/or a bad variable timing control (VTC) actuator. The vehicle performs well despite the “check engine” light. However, it is concerning for a failure would be catastrophic. Alternatively, it could be that only the onboard computer is out of synch and the engine is fine.

So…

a) I suspect my VTC actuator may be bad, a common complaint on this vehicle - denoted by a signature rattling noise (ie: metal on metal) for about 2 seconds while turning the key. The complaints are always at cold start-up and typically in cold weather. Recently, however, I hear a similar short-lived rattle when I accelerate at times. Since this is a variable timing control device…wouldn’t one expect this device to be problematic at various operating points beyond start-up? (What does this device do, anyway? …make an engine perform without a jerkiness as engine rpms vary?)

b) Some say the timing chain cannot stretch since it has such a high, tensile yield strength. Others state they have witnessed a chain skipping 1-3 teeth (of the cam, I wager?) due to a stretched timing chain. (No, I do not mean a belt.) It does seem hard to imagine a timing chain yielding when car makers claim the timing chain to last the life of the engine. What do the SDopers have to say about this?

c) If the issue is the computer, is there a way to re-calibrate the sensors and put things back in synch? If not, will living with an out of synch computer keep trying to adjust the engine when adjustment is really not necessary? Could this be catastrophic, as well?

Timing chains do stretch in the sense of getting longer, due to the accumulative effect of very slight wear in every joint (there are a LOT of joints). They do not stretch in the sense of each piece of metal elongating, but in the real world that’s a useless distinction. I have seen a great many timing chains that were loose due to stretching, and quite a few that jumped teeth because of it.

Do any carmakers really claim the chain will last the life of the engine? While replacement is not listed as a maintenance procedure, it is widely understood that it may need to be done at some point, like any number of other repair situations.

uh, yes? timing belts last 100,000+ miles, why should chains not last longer?

Since my rubber tires are expected to last 50k miles I should get more miles with the steel treads on a excavator?

They use timing chains on some engines because that’s the strength required, it’s not so it lasts longer.

Back to the OP, question from Jinx.

A brief search shows that the chain (yes, chain, not belt in your car) can stretch and cause this issue. Honda seems to be aware of this problem without a fix, other than replacing the chain, etc. A couple of the user questions I saw sounded like they may have been asked by Jinx, they were so similar. You could try replacing your VTC actuator but that may not be it. I do not know the relative costs of each procedure so it’s up to you. If it is simple and relatively cheap, try that first.

Or you could try the time honored engineering concept of “operate until failure.”

Not true.
I don’t know of a belt that is rated to last more than 100,000 miles. Chains (like in my 2000 F150 V6) have no scheduled maintenance, and typically outlast the engine.

the belts in the Ecoboost 1.0, 1.5, and 1.6 have a replacement interval of 150,000 miles.

I had a 1979 Honda CX500 motorcycle - after its first major trip, it was making funny noises, I had it looked at and the “cam chain tensioner” was broken. This bike had a camshaft driven by a chain, then that ran pushrods for the valves, like 1/4 of a V8 before overhead camshafts. (IANAMechanic) I would presume the OP’s possible problem would be whatever keeps the chain taut (An idler wheel that takes up the slack on the return leg of the chain path?) has broken, hence the chain “slaps” back and forth at low speed and makes funny noises. That could also give a timing error?