knocking engine question.
 

This is the second car I have knocking experience (2000 Lexus ES300). The car has been very nice, smooth and strong. It is still very smooth and strong but whenever we are going up the hill, it'll knock very bad/lound and weak. Off the hills to flat surface, it's back to normal. Multiple times, I did try to shift to 2nd and 1st but it's doesn't get better. Anyone know why/what?
Engine oil: valvoline 5/30
Thanks in advance.

Try 91 gasoline and see if the problem stops.

Does it knock when cold? Right when it's first started? If so that's a sign of piston slap.....I think gogar is right and could need higher octane fuel, most lexi need 91 iirc.....

Are we talking knocking or pinging?

I see that you are in CA. Could be the boutique gas, and a bad 'knock' (ping) sensor.

If it's a knock you really have, it's a knock, and you'll soon be down in Santa Ana looking at long blocks.

What OBD codes does it show?

If your engine knocks, answer it!

****

Just kidding. I always thought Toyotas didn't have problems like this.

now I am not sure if it's knocking or pinging. It's loud and only happen when clambing up the hills. If I don't clamb hills, I would never hear it ever.
I will try 91 octan to see what happen. Honestly, I always thought all japanese engines are running 87 octan.
Thanks.

Probably has something to do with the p1ss they try to pass off as "gasoline" these days. Ethanol and other crap probably makes up more of the formula than actual gasoline nowadays. It's garbage.

I have the same problem with my wife's Toyota. An occasional tank of 91 solves it. Maddening because the car is supposed to run fine on "inexpensive" 87 per the operating manual.

If it is making the noise under a heavy load, it probably is pinging, . You should check obd 2 codes, could be a faulty knock sensor, ( I think your car has 2) but more likely than not, there are deposits built up on the tops of the pistons, and valves which will make your combustion chamber smaller, and therefore effectively raising compression ratio. A top end engine clean just may help to clear up the problem, and wise advice was given above to run a higher octane fuel. If the noise is gone , or not as frequent with the better fuel, then, you are on the right track.

Perhaps an Italian tune-up?

I'm 99% sure it is pinging from pre-detonation. But not necessarily from low octane.

Those engines (1MZFE) were notorious for carbon build-up around the valve seats, and sludge build-up internally. Run Sea Foam through the intake and it should help. And you should be running 91-93 octane fuel.

Describe the noise. Is it a tin sound like a can getting hit with a spoon? Then it is pre-ignition. Could be ignition related as well, if higher octane doesn't clear it up. You should not run it like this for long - you may get some broken rings from it ....

George

GM used to market "Top Engine Cleaner". Stuff was outstanding for cleaning deposits from the valve train and combustion chambers.

Modern cars automatically compensate for octane by retarding timing. You could have a bad knock sensor/computer, carbon build up, or worse case a partially blown headgasket. If it's blown between cylinders or into the valley, you won't necessarily get the exhaust steam or water in the oil. You could even have a clogged cat when the exhaust is retricted. Also could be fuel delivery related and knocking from lean mixture.

Pretty tough to guess based on limited info. I would recommend getting it looked at before you knock holes in a piston or damage bearings. It likely will only get worse when the weather gets hot.

I have to know. Is that flat out for as long as you can stand it?

I kindda think it's not a broken rings or major already damage because the car run great, quite and smooth on normal street. The problem is only when clambing up the hills. Also, I just did the timming belt kit. After this service, the mechanic test drove it around. He told me the car is great, the only thing I need soon is the tires. I will get 91 octan and clamb hills again to see if it's still there. Actually, I will record the sound and post when I have a chance.
Thanks.

Kinda'...

It basically means drive the snot out of it. Keep the revs up high for a half hour or more. I do this every time I need to get a car smogged - can of Seafoam and an Italian tune-up immediately before the smog check. I've always passed with this method.

rev high for 1/2 hour? Are you exagerating it? :D I thought it should be around couple mins max.

Did the car ping before the timing belt replacement?? . A cam sprocket that is one tooth out, could also cause pinging

Like was mentioned, if this problem didn't exist prior to the timing belt replacement, you need to get back there and have the mechanic recheck the timing. If the belt is off by one cog, the computer can't compensate for that much bad timing. Don't bother recording the knock for us... knock is knock. Get it checked out sooner rather than later.

+1 the timing belt could be one tooth off and the car will still run ok. Not great, but ok.