I recently purchased an 2006 LS 430. I noticed that if I have the key on ACC or On, for awhile and then try and start it, it tries to turn over but doesn't start. If I turn the key to off and then try and start, it start right up. What might be going on? Thanks

 

In what circumstances are you leaving the key in acc but not cranking? Have you considered not doing that?

I'm no expert but to me in even the most sophisticated cars for me it comes down to two things essentially, fuel and spark. Are you saying that it needs priming basically by turning it over for a while? Fuel pump issue? Or if you go out there and it's cold and go straight to cranking it it fires right up?

 

I'm not a mechanic (as indicated in my tilt motor question), but doesn't fuel rail / fuel pressure on many cars prime up when you turn from off to accessory? Not sure if that sequence applies to pushbutton start cars, but LS430 is not that.

Below is an ai-chat-generated response to my q... I am not sure how long you are waiting, but perhaps it is losing fuel pressure. That could be normal? Take with due caution...

"Yes, if you turn the key to the accessory position and then to the starting position after a while, and the vehicle struggles to start, it could indicate a loss of fuel pressure. This is because the fuel system needs a certain amount of pressure to properly deliver fuel to the engine.

Fuel pressure typically primes up when the ignition is turned on. In many vehicles, when the ignition is first turned on (without starting the engine), the Engine Control Unit (ECU) or Electronic Control Module (ECM) will trigger the fuel pump to run for a few seconds to build up the necessary fuel pressure234. This process is often referred to as "fuel pump priming"

After this initial priming, the fuel pump will not activate again until the ECU or ECM receives an RPM signal, indicating that the engine is cranking or running. This ensures that the fuel system is primed and ready to deliver fuel as soon as the engine starts."
etc.

 

Having just got the car and had owned an 1995 LS 400 for 300k miles, I left on ACC to play and understand all the new features without keeping the engine running.

the fuel pressure response makes sense to me. Thanks.

 

When you say try to turn over I am assuming you mean slow crank and problem is most likely the battery or battery terminals need cleaning. Fuel pump does not come on in ACC. You can also measure voltage at battery and battery terminal connector when cranking. Turning off and immediate on crank puts heavy amperage immediately which to me sounds more like needs cleaning. Easy to diagnose.

 

When I got the car brand new battery put in while I was there.

 

Ok...Test with voltmeter directly on battery post and then on battery connector. Does it crank slow when not working properly?

 

I will check that. It cranks the same. Just won’t turn over. Like theres no spark or fuel. That’s why I’m thinking it may be the fuel pressure someone commented on. Great input for me to investigate further. Thanks

 

Then forget it being the battery. Just turning to ACC should have nothing to do with the fuel but if turn too far to Ignition then back to ACC could cause the fuel problem. This system could sense being in ACC for awhile and not energize the fuel pump going forward from that point and needs to restart. Interesting and I will try my 2001 UL next week when back home. How long do you have the ACC on so I can test?

 

OK, if you are playing around with your new car, here (below) are a few non-mechanical goodies I like about the LS 430 that you may or may not have encountered/realized: My parents had a 95 ls400 for 200k miles, which convinced me to buy my LS430 back in 2009. They loved their car and today have an es350, but I love the LS430. I find it just enough larger than their LS inside that it has always felt the perfect size. One other difference is that they always had horrible trouble getting traction on their LS400 in any kind of snow, or so they claimed. Even with all-season tires I've owned my LS430 15 years and it has not been a major issue except once when stuck on deep snow and ice in a driveway. Bur I nearly passed on getting a RWD car... I do have all-weather tires currently but even with decent all-season tires in past the car has been reasonable in snow.

Anyway (and others have discussed before):

(1) the area above the rear view mirror has a separate mini-visor you can fold down. The more modern (?) cross-hatching windshield blocking is not present.

(2) Most obscure, possibly: The front seats each have a storage drawer built in, accessible from the front of the seat. Not one I use often.

(3) My absolute favorite (not sure is LS400 has this): Extra side bolsters (fabric-y flaps) on the front seats. They have saved me many times from losing my cell phone under the front seat. I wish my other car had this.

OK, two more...

(4) The door pockets flip out. It is SO MUCH better than fixed, molded plastic for getting things in and out of the door pockets. Never had another car that does this.

(5) The entire seat bottom adjusts on driver's seat for thigh support. On newer cars its like an uncurling extension. Can't say if LS is better, but seems more solid to shift the entire seat bottom.

Really, the car is amazing. If it had a heated steering wheel and an auto-release parking brake it would be even more nearly perfect. (Plus a battery protector/lights shutoff, in case you leave an interior light on or a door open with headlights on. Don't!)

I love the swivel/AFS headlights by the way. They are the widest beam pattern I have ever seen. I am not sure how they would rate among formally tested cars in absolute distance of low beams, but they are by far the best headlights I've ever had for overall visibility. My Cadillac 2016 xenons suck. I cannot see into the turn I am trying to make to see the road I'm turning into. I've had a recent es350 loaner. Brighter/whiter perhaps, but not the same overall visibility in turns, where the side road you are trying to turn into is lit so you can see where to turn. And that is NOT from the swivel headlights (which are great while driving at speed and going around a curve), it's from the beam pattern width and possibly marker lights.

Good luck with the car. Custom is the perfect trim, IMO, for durability, as you can get radar cruise (hope you have that) without the air suspension! I got the ultra for the radar cruise. Shipped from Chicago to NY back in 2009.

 

My 95 LS 400 had most of that and the LS 430 is more better, as my grandchild would say. One item i found was a connection for a trickle charge. If you look at the battery cables closely, there is a pigtail with a 2 cable connector. My buddy told me if you need to leave your car in storage or idle for a long time, connect a trickle charge using the pigtail connector to keep your battery from going dead.