bradland

Detonation AKA preignition AKA spark "knock" will eventually cause permanent engine damage.

Sin1UZFE

It's there a great danger of that if 91 or higher octane was used?

Sherl

How can I limit the damage in the mean time? Do I have sometime?

I found the part numbers here for the sensors
https://www.ebay.com/itm/2-DENSO-GEN...S/223608896472

bradland

Improper fuel (octane rating) and excessive heat are prob the 2 biggest contributors but it can be caused by several things...
Causes of pre-ignition include the following:

• Carbon deposits form a heat barrier and can be a contributing factor to pre-ignition. Other causes include: An overheated spark plug (too hot a heat range for the application). Glowing carbon deposits on a hot exhaust valve (which may mean the valve is running too hot because of poor seating, a weak valve spring or insufficient valve lash)
• A sharp edge in the combustion chamber or on top of a piston (rounding sharp edges with a grinder can eliminate this cause)
• Sharp edges on valves that were reground improperly (not enough margin left on the edges)
• A lean fuel mixture
• An engine that is running hotter than normal due to a cooling system problem (low coolant level, slipping fan clutch, inoperative electric cooling fan or other cooling system problem)
• Auto-ignition of engine oil droplets (Can be solved by using an oil catch tank)[3]
• Insufficient oil in the engine
• Ignition timing too far advanced
• Excessive amount of oxygen in the combustion chamber

Sherl

I am trying to verify the knock sensor harness for 98+ LS. Please let me know if find any. As of now I have
82219-50010 but not sure thats the right part.


Meanwhile
Lower Gaskets https://www.amayama.com/en/part/toyota/1717150020
Throttle body gasket

bradland

It looks like the wiring harness has been discontinued.
The best way to verify part numbers is with a dealer- https://www.mylparts.com/oem-parts/l...Y4LWdhcw%3D%3D

No need to pay dealer prices for the TB gasket-
FEL-PRO 61281

Sherl

I use epc data I couldnt find the knock sensor diagram at all
https://lexus-usa.epc-data.com/ls400...l/2128/engine/

Sherl

Thanks for the gasket part number.

Sherl

I also found out that leaky capacitors can do that as well. Someone in the thread suggested to replace ECU capacitors.

bradland

Bad caps aren't really an issue on the 98-00 cars.

Sherl

Guess you are right and I spoke to DriftMotion they suggested me to check for resistance between the wires before I replace. I also couldnt find the wiring harness for the sensors as from my research its that wiring harness go bad rather than the sensor itself. So, I am stranded at this point of time.