aprairie

Hey all,

Great forum, and a great resource that helped me settle on picking up a certified 99 from the local Austin dealership. Car has about 33K on it, and in general has been great. Had a few problems (squeaky suspension, squeaky breaks) that the dealer took care of under warranty. But one problem has persisted and I'm not sure I like the answer the dealer is giving....

When I first got the car the engine knocked/pinged like crazy whenever we were driving uphill and kept the RPMs at around 2 to 2.5K. Took the car back to the dealer, they said they probably put a bad tank of gas in it and would refill with premium and put some BG44k in there. Seemed to work ok for a week, then on the next fill up with 89 octane gas the pinging returned. I thought ok, I'll use 93 octane next fill. Did that, and it did improve the problem but the engine still knocks.

Took it back to the dealer and they saw nothing wrong with it. Went driving with a tech and I showed him how I was driving and repeated the problem. He smiled and immediately "diagnosed" the issue. I'm babying the car....

He said the engine likes to change gears at 3K RPM and that my slow accelerations were causing carbon buildup that resulted in the ping. He said I needed to switch to the power shift mode and accelerate quickly. This would help burn the carbon build up and should solve the problem. Never mind that now all I'm doing is passing over the 2 to 2.5K RPM much faster so I can't hear the knock. He also said I should fill every other tank with 93 octane gas. "THe government made us say that the Rx could run on 87 octane, but it will cause the engine to knock." No answer why the government didn't make them do the same for the other models....

Am I missing something, or is there some logic to this approach? Could there be another problem? Right now, unless I use 93 octane gas the car knocks loudly. Any thoughts?

Thanks-

commack4

Although I don't agree with the dealer, I would try the following based upon the potential oil sludge buildup problem that is notorious with the Toyota V6. Before your next oil change, run a can of motor flush at least 10 minutes in a warmed up engine, then proceed with your oil change as usual. This MAY provide a longer term cure than 93 octane and other temporary additives!

wwest

Should be replaced right away.

I don't understand why the dealer didn't do this immediately, inexperience maybe?

Your engine is subject to the engine sludging problem but I can't imagine how sludge within the oil "passages" would cause pinging. Unless the pinging only occurs after the engine is fully warmed up and that would indicate engine "hot spots" due to the sludging, maybe.

mooretorque

I agree with wwest. Modern engines just DON'T KNOCK. The knock sensors, integrated with the engine management computer (ECU), can detect knock before it's even audible to the driver and retard engine timing in less than a thousandth of a second. The process is, to all intents and purposes, instant, transparent and constant.

The issue of performance and mileage on 93 vs 89 vs other octanes has been addressed several times. The RX does not benefit from use of 93 octane since the engine parameters have been optimized for lower octane gas. Nor did the feds tell T/L any such wad of crud as "THe government made us say that the Rx could run on 87 octane, but it will cause the engine to knock."

Your dealer is giving you the ol' ramalamadingdong. Wifey's RX ('99 with 45k miles, bought new 5/98) has NEVER pinged on 87 octane. Nor has any other poster running 87 reported such during the octane debates. If you need any further proof, ask yourself why your RX knocks even on 93 octane!!!!! I'd go to another dealer. If all else fails, use the 1-800 Customer Satisfaction #.

billyboy

My 2000 RX has never had anything but the "regular" 87 octane gas in it since the day I bought it new. I has never never pinged. I have 19k miles on it. I would definitely go to another dealer and report the one you did go to for incompetence.

spinteews

engine knock, "pinging" educate me guys

wwest

What you hear when you set near a Ford or Dodge pickup with a diesel engine. Fuel being ignited before optimal, resulting in significant explosive "push" backwards on the piston even before it completes the compression cycle and arrives at TDC, Top Dead Center.

Can be severely detrimental to gasoline engines over time, holes in the top of pistons, etc.

mw1

I'd also be concerned about the long-term implications of what all this detonation has done to your motor.

aprairie

thanks everyone. going back to the dealer one last time before I call T/L corporate. Unfortunately, only other Lexus dealer is 60+ miles away, so I'm a bit stuck in terms of service. at least now i feel a little better armed when i talk with them.

drew

Sewell

iTrader: (9)

Its you mass air flow sensor (22204-07010). Here in Dallas, we are replacing about 10 a month for the same problem!

MellonC00

My MAF Sensor is being replaced today for engine knocking. Apparently, this is quite common in RXs. I had the same problem with my car. Let's see if this will fix the problem.