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Lx450 Pinging With 93 Octane


Andrewsreef

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Hi all, I just replaced the knock sensor on my LX450 after having intermittent problems with my check engine light and code#3025. Even after replacing this, I am still having a little bit of knocking I notice when I give it gas pretty hard just before and after the transmission shifts. This does not seem normal at all to me and the noise drives me nuts (I have an ear for this kind of stuff).

Any sugustions? My timing is set to the factory specs of 3BTC and I just had a tune up and injector cleaning/throttle body done. Anyone else notice this? I am starting to wonder if the quality of the gas has changed lately because it has not done this since I got the timing corrected with my tuneup.

thank again.

Andrew

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Andrew,

I've heard of people having this problem when advancing the timing, but not when it's set to factory specs. And you said that you replaced the knock sensor too?

FWIW, I don't have that problem in either of our LX 450s.

...

Doug

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I do have the timing set to the factory specs. Not advanced. This was done during my tune-up and I have checked it again to be sure. THe knock sensor was replaced due to my check engine light coming on and off for a code #3025. This relates to a short in the knock sensor or harnes. I am the guy who had the strainge problem with the wire harness but that was fixed and the erratic behavior from the truck is all fixed now. I replaced the knock sensor as it is the #2 thing to check when you have the code 3025 problem according to my manual.

Thanks, do you run regular gas or 93? Does yours knock at all when you jump down on the gas? Again, I really have an ear for this stuff.

THanks

Andrew

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I run regular, not premium, in mine. Have never had a problem with pinging. The higher octane is supposed to control pinging -- which is why I find you situation so odd.

If you do switch to regular fuel, you should note that it may take a few hundred miles for the ECU to reset.

I'm getting ready to head out the door, so I'll listen closely to see if I hear any pinging.

...

Doug

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Not sure on the valve clatter but I beleive that would be noticable at idle. The spark knock or pre-ignition clatter is different sounding to me. It is very high pitched almost matelic sounding. It can be hard to hear over the engine. The exhaust can make a similar sound also but I really beleive mine is "pinging" just a little before and after it shifts in the higher RPMs.

Thanks

Andrew

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You could always get a wide band air/fuel gauge to check to see if you do indeed have pre-detonation. IMost good dyno shops have them......except the LX has full time 4wd......you can still have the truck data-logged and then you can tell for sure.

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Andrew,

You may want to try higher octance gas and see if the problem temporarily goes away, then you can go from there and keep on trouble shooting.

If your spark plugs are old, you may want to get a new set of spark plugs; check the spark plug wires also.

Thi

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Thi, thanks for responding. Do they sell gas with a higher octane than 93? I was think of switching brands and see if that helps. All the plugs and wires were replaced trying to fix my misfire problem from the bad wire harness. Not much left to replace on this thing.

Thanks

Andrew

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Andrew,

I don't know what I was thinking, sorry. 93 octane is high already. I just read in a book and it metions some other causes for preignition/pinging: engine running too hot, carbon build up, sharp valve edges, glowing exhaust valve. Currently, I assume that your car does not have any error code.

Thi

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Thi, I have heard that carbon buildup can be a problem but no idea why I would have it after the cleaning and tune up. I ran some Amoco 93 in it this week and the knocking is better but not completely gone. I have to jump on the gas pretty hard to get it to ping though and it only does it a few times before and after it shifts. I am going to do some research on the timing for these things and see how much total advance they are supposed to get. Not sure what controls it but I assume it is the computer. I may take in to a new place I heard about that does a lot of work on Landcruisers locally. I will let you know what I find out.

Thanks again.

Andrew

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even if the engine lights is not on you might check for error codes. when i did timing belt change on my friends LS we set timing just a lil bit off the factory settings and it gave us same problem as your plus misfiring around 3-4k rpms.... just a guess. ..

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