afpj

Hope someone has some suggestions: I can't tell if it's a knock or valve clatter. The noise occurs when driving steady, up a slight hill (or even a steep hill just not downhill) when holding speed at about 1200-1300 rpm but less than 30 mph. Pressing on the gas to accelerate makes the noise disappear, so it's not your typical engine ping. Tried 91 octane for a month, and not only did we see no difference in mileage, it makes no difference for this pinging sound. Anyone encounter this before? PLenty of posts on engine knock/ping, but more of the typical stomp on the gas and get the noise, not holding steady and get noise. No CEL, No codes when hooked to scanner. Mainly noticed it this summer, and it's over 100 deg F daily here. Temp gauge not even to 50%. I do not have a tranny cooler (as far as I can tell). Thanks for any info...05 RX330

lexus114

WOW,no codes,no ck.engine light? Maybe its carbon build up,Try getting some BG44K and run that through the gas.Could also be your valves out of adjustment,you may want to look into that as well.Maybe your timing belt jumped a tooth,(advance) and is causing a problem their(doubt that one though).That is about all I can think of at the moment.

afpj

Thanks for the suggestions. Will pull a plug or two next week and run a flex scope down to look at piston head. As for timing, I guess I'll have to look at a manual to find where to aim the timing light, or am I dating myself and these fancy electronic controlled everything cars can't use a timing light? May require a real mechanic next week. Again, thanks.

erick3

All cars ping a little bit, and it's almost impossible to completely get rid of it. Despite, you mentioned that you used 91+ octane gasoline for a month and it did absolutely nothing? Well...that in itself could be your problem! The dealership, or should I say stealership, in all honesty, recommends you use premium gasoline for a reason - your motor was BUILT to run on 91+ octane gasoline. without it, you lose performance and mpg. it has to do with the resistance to combustion - the higher the level of octane, the more it takes for gasoline to "burst". Lower octane levels have less resistance, and thus explode easier - specifically in our 91+ octane motor: lower octane gasoline doesn't burn 100%. FROM that - your motor gets warn down - thus the knock sensor - tries to retard the combustion - gives you the pinging. Best thing to do: SEAFOAM motor treatment and use 91+ octane gasoline.

...does that even make sense? lol...tired

Lexmex

Try if possible a 93 octane or supreme unleaded for a week or so as a test. There is a noise I use to get that I thought was a rod or perhaps a valve issue (I have neither), but what it ended up being in my RX300 was the clutch plate (connects engine to the transmission). I am convinced some of my high speed drag racing antics did it, but only when I had a cracked transmission pump after a small accident was this noticed, and it can make a noise similar to a ping. That's probably unlikely there.

However, an issue that I had even before that in Mexico City, and I got used to it, was using 92 octane Premium combined with the low oxygen content in the air at high altitude. The combustion wasn't quite right, but it would not be detectable by a CEL. What can occur is that high air temps aren't the best for proper combustion. Ideally, we'd prefer having nice cool air enter the engine. I'd notice a different during the winter months the ping so to speak I would get in other months would be less, but I still had to deal with it. Only when I'd get to sea level say in Texas would I not notice it as much.

And as you said, when you stepped on the gas, the issue would go away, and that would be due to getting fresher air into the system as opposed to just sitting at idle and taking hot, stagnant air.

Grumpa72

Well, no one has suggested what I was thinking, so I will put up my obscure thoughts on this. I know very little about the internals of this engine but, if this was a Chevy V8, I would suggest that you have a main bearing going south. Again, the qualifier here is that I am intimately familiar with the old school V8s of yesteryear, but I can only assume that today's engines share most of the same operating principles.

It has been suggested that you have pinging, despite your initial comments that premium fuel didn't do the trick. Then it was suggested that carbon build-up may be the culprit. I can live with that suggestion. Try a proven carbon build-up remover and then go back and try premium fuel to see if there is any improvement.

If this is a rod or crank bearing then further investigation needs to begin. In my experience with the older engines, a main bearing that is worn will usually manifest itself with mild knocking noise that goes away under acceleration. It is usually most prevalent during gas-off deceleration and steady state cruising.

lexus114

Also,when switching to the higher fuel,to help the process you should reset your ecm.

afpj

I sure hope your wrong Grumpa (yikes!), we'll see later this week. The spousal unit doesn't want me to do anything "invasive" (CPO still under warranty) so she's taking it to the dealer...my bet is they won't find what we're talking about. I'll pull that ECM fuse and see if that helps (not too invasive) Perhaps if Lexmex is correct, it will be much better when the temp drops below 100 F around here. BTW, can't find 93 octane around here.....Thanks guys!

Lexmex

Basically use the super unleaded or the highest price gasoline a station offers, that's all you can do as a test.

sail7seas

If your engine air/fuel is running to lean, it will prematurely knock.
This can be caused by several things, but what comes
to mind is dirty MAF.
However, O2 sensors switching slower with age
would NOT throw a code.

Chpsk8

05 does not require premium. It's in the owners manual and touted by the dealerships that this model does not require premium. It will benefit from premium but does not require it.
Also... Seafoam is probably not the best thing to add to a modern engine. It has a very real possibility of gumming up the o2 sensor if you add too much. I would recommend a top tier fuel along with an injector cleaner. No mention of mileage from the OP, so plugs might also be in order.

lexus114

Ya know I thought about that,(lean burn)But I thought it would send out a code.Especially obd2

Lexmex

It might be a pending code. Might not light up the cel, but if you hooked up an OBD2 scanner to it, it might be in there.

afpj

sail7seas,

If too lean, should it knock all the time, or should I say knock in the typical acceleration scenario? Mine only knocks when holding steady at a low rpm (1200-1400) on uphill. When you step on the gas the knock goes away. I'm only use to the old fashioned knock/ping on hard acceleration like with my older truck. Maybe this fancy shmancy RX does different? My 05 RX has 67K miles on it, and the OBDII scanner I stuck to it can read pending codes (or so it says in the manual), but no pending, freeze frame or active MIL codes on that scanner. At 60K miles, dealer did a fuel injector service, whatever that was. Maybe they didn't and just charged for it!@#%

lexus114

I wonder if it is piston slap? Or cracked piston.