Clatter/clammor/rattle Under Slight Load

[blk_on_blk]

Hey Guys, I've got an annoying little clatter/clamor coming from my engine under slight load (and when it's warm out) in my 1996 RX300 (145K miles). I almost never notice it with the windows rolled up, but now that we've been getting some 80 degree weather, the windows went down and I can hear the noise again. I keep defaulting to, "Oh, it's detonation I should probably replace both the knock sensors," but then then sound is a little more crisp and clear than other engine pinging I've heard in the past. It sounds more like lifter chatter... kind of a gurggly chatter, and it's controllable. The engine is smooth and quiet with minimal or normal load (and at idle), but give it a little gas on a slight incline, and I can hear the chatter, push on the gas a little more and it gets more pronounced, but then let the RPMs climb a bit and dig in deeper on the gas pedal and the chatter goes to a 'gllllrrrrUP!', stops, and the engine pulls strong, hard, and quiet. It's right in that 'pinging' range/pattern, and follows the sound with load and fuel addition, and also gets out of the sound once up into the powerband, but the sound isn't like pinging I've heard before.

Before I go and dig into the engine to replace both the knock sensors, has anyone else experienced this? If so, were the knock sensors the correct fix? Or was it something else?

Thanks in advance!!

[lexus114]

Hey Guys, I've got an annoying little clatter/clamor coming from my engine under slight load (and when it's warm out) in my 1996 RX300 (145K miles). I almost never notice it with the windows rolled up, but now that we've been getting some 80 degree weather, the windows went down and I can hear the noise again. I keep defaulting to, "Oh, it's detonation I should probably replace both the knock sensors," but then then sound is a little more crisp and clear than other engine pinging I've heard in the past. It sounds more like lifter chatter... kind of a gurggly chatter, and it's controllable. The engine is smooth and quiet with minimal or normal load (and at idle), but give it a little gas on a slight incline, and I can hear the chatter, push on the gas a little more and it gets more pronounced, but then let the RPMs climb a bit and dig in deeper on the gas pedal and the chatter goes to a 'gllllrrrrUP!', stops, and the engine pulls strong, hard, and quiet. It's right in that 'pinging' range/pattern, and follows the sound with load and fuel addition, and also gets out of the sound once up into the powerband, but the sound isn't like pinging I've heard before.

Before I go and dig into the engine to replace both the knock sensors, has anyone else experienced this? If so, were the knock sensors the correct fix? Or was it something else?

Thanks in advance!!

What octane are you using?,if it`s premium it may be lazy knock sensors or carbon build up.If your using Regular,bump up to mid grade and see if that clears it up.Engines requiring a higher octane with millage/age is common,due to valve wear.

[blk_on_blk]

I'll fill up with premium on this next round and report back... thanks!

I've run Seafoam through the intake, so I would think that would clean out any excessive deposits (although carbon deposits are pretty tough to clean out). Assuming there isn't any major build up of deposits, and the higher octane fuel still results in the noise, then I guess the knock sensors are the next focus?

Thanks again!

[RX in NC]

Are you still running the original factory spark plugs? The Denso iridium plugs are fantastic and will often deliver 150,000-plus miles with no problems, but if you're still running your original plugs I would consider changing them as well....

[blk_on_blk]

Plugs and injectors were changed out about 15K miles ago... using Denso iridiums as replacement plugs.

[blk_on_blk]

Lexus114, you're input seems to be spot-on. I filled up the last two times with premium and the clatter/clamor/gurgle is gone. Of course, the weather here has changed and cooled off significantly (and the noise seemed only present at warmer temperatures), but in some testing, the premium fuel seems to have really helped. I thought I had done this before, but perhaps I had just switched to Plus, but not premium.

Anyhow, even though I'm not getting a knock sensor code, I'm wondering if changing out the knock sensors will allow me to run regular grade fuel again, or has time & wear done its thing on my engine and I just need to run premium fuel from here out?

Thanks for the input... it helped!! At least now I know it's not a valve-train noise, but rather detonation!