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The new Lexus LS430 is speed limited to 130mph by the Electronic Control Unit.

Probably because the factory tires are HR rated (130mph). Early LS were not speed limited.

Can the dealer deactivate or reprogram the ECU?

If not, who makes a reprogrammer or module to deactivate the limiter?

Of course, the above is undertaken with a change to YR rated tires (186mph). The Euro suspension should be able to handle 150mph if the engine is up to it.

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U.S. spec. 1990 - 2000 LS400's were electronically limited to about 149 mph (240 km/h) due to the V speed rated tires. The November 1989 Automobile Magazine I'm holding in my hands list the top speed of a 1990 LS as 150 mph. The U.K. Lexus website used to have top speeds posted for all years of LS. The 1990 - 2000 U.K. spec models (and Euro spec mdels) were electronically limited to about 155 mph (250 km/h) as are the U.K. / Euro spec spec LS430 in accordance with a voluntary agreement among manufacturers for maximum allowed speed for sedans. LS maximum speeds for various countries can be reviewed via

I doubt that a dealer or repair shop would defeat the speed limiter due to liability issues.

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2k and above models are limited not due to the tire type but due to the US laws for the maximum speed. i think all cars that are allowed for street use in US cant go any faster. max speed of 95-97 LS is 156 mph.

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also there is a way to reprogram your ECU for the faster speed it is highly not recommended plus it is illegal to do so and WILL void your insurance and warranty plus some criming charges in case smth happends.

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Thanks for the replies. I don't think there is a federal or Tx state law referencing maximum speed, although there certainly are speed limits on roads (state laws only). My Vette comes without a limiter and will do over 180 from the factory with no changes. I do know that the European Union has a voluntary limit of about 155mph that Mercedes, BMW, etc hold to. US imports of those cars are likewise limited to about 155.

There is no federal or Tx state law referencing reprogramming a speed limiter. For that matter, there is no law prohibiting cheap tires with no speed ratings being used on any car after it is sold initially in Tx. Some states (eg, California) may severely restrict engine mods that may affect exhaust emissions, but speed limiters are not included.

Tampering with the ECU may well void or affect the manufacturer's warranty, depending upon the manufacturer. The major driver of manufacturer and dealer behavior today is legal liability. It seems that individual responsibiity is severely passe. If you douse yourself with gasoline and set fire to yourself, it is solely the fault of Exxon or Bic lighters. So I am not surprised that dealers and Lexus choose to avoid any involvement.

That still leaves the question: How does one make the change if one is willing to accept the responsibility for it?

Thanks again


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