Hey everyone,

Long time lurker, first time poster. I've had an awesome 98 LS400 for over two years now with 175K on the dash. Recently I've been having some weird starting problems. The car starts right up fine when cold but sometimes after driving it doesn't want to crank back up. This has happened twice in the last month but once the car sits it seems to be fine. I've been searching the forums and it seems it could be a temperature sensor or possibly the well know ECU issue. I'm in TX so the car is never really "cold" but I've only had the issues now that it's been over 100 deg. Any help would be appreciated.

 

Exact same thing happening to my 98 LS400. Remove and inspect vacuum hose from PCV Valve to intake. The back of these crack and suck a lot of air. Remove and inspect all the other vacuum hoses too, replace if cracked or brittle, armor all them to return supple. Idler pulley noise? spark plugs changed? running regular unleaded? cleaned the throttle body? broken vacuum fixtures on black air box? Stretched throttle cable? Whine noise from throttle body after intermittent no start? Broken/cracked key fob? cheap/weak battery? alternator check? Sorry it is a long list. But, all these can be a cause. Disconnect the battery every time you do work is a must to keep the computer happy. I would start with vacuum hoses. Oh, if the throttle body whines after a a no start, disconnecting the battery and unplug/replug in the throttle sensor, reconnect the battery, give a little gas, and mine starts so I can get it home.

 

When you say it doesn't want to crank back up do you mean it's not turn g over at all?