Lexcob

Thanks guys I was wondering where the ECU got its signal from to adjust the idle valve in the first place so that answers that. I'll start there to make sure that is sending a signal first. Then I'll move on to the other points. Thanks I'll report back.

Thanks for that, that is interesting what constitutes a reset of the ECU? For instance if the battery to totally flat for a long period of time or has been briefly disconnected can this cause a reset of the ECU? This did occur recently and since then only around 10 miles has been covered? Could the ECU still be 'learning' again? Just as an additional point the engine is no longer in a Lexus and it is not mated to its original auto box, but on a conversion to a Supra 5 speed manual box, but I guess the ECU will still make the adjustments to the idle speed? Thanks for your responses.

Ok thank you for that.

OK thanks Malc, lets see how that matches up with others but it does sound more what I would expect.

Hello I'm new to this forum but I was looking for a little advice and guidance on the normal idle speed for the LS400 engine. My V8 is no longer in a Lexus but transplanted into something else. The engine idles around 1200 -1400 rpm even when the engine has warmed through, is this typical? It is steady at this rpm so it is driveable, it just seems a bit on the high side to me. But since I have no experience of the LS400 power plants I am not sure. Or is this one of the symptons of the Idle control valve on the front of the engine perhaps needing a clean? If so can anyone point me at a 'how to ' guide. Some the guides and videos on the web seem somewhat inconcise to me. Am I right in saying that you can't get anything like a Haynes manual for the LS400 as they never printed them? Thanks in advance for any help. David