sp16

I am experiencing intermittent difficulty starting my LS460.

The starter cranks and the engine tries to start but doesn't catch. If I try a second time it usually starts ok.

3 in 5 times it starts after just two or three cranks, then others it just cranks and struggles to catch for several cranks.

Lexus dealership commented that in the service the car was slow to start and suggested the crankshaft sensor might be going bad, despite no codes being present.

Do these symptoms sound right for the diagnosis? Or any other thoughts from those who've experienced this problem?

Many thanks.

Junglequac

How many miles are on the car? In addition, how old is the battery and did this present once really cold weather set in? Hopefully not the crankshaft sensor as not a very cheap fix.

I have not personally experienced it, but have only had my 460 around a month. Did the search feature come up with any similar instances?

sp16

I just got the car (minus warranty) a few days ago... it's on 92k full Lexus service history all recalls done etc.

I put about 200 miles on since getting it and haven't noticed any sluggishness from the battery, although when I went to view the car it had a "low battery" message before I first started it up.... which I haven't seen since as it's been used and should be charged now I guess.

It behaved fine every time I started it before buying, just bad luck I didn't experienced the problem at the time!

The car doesn't misfire that I can tell when running and RPM sit steady when ticking over. When accelerating, there is a 1-2 second pause before the power surges in but I have put this down to the gearbox changing down.

Junglequac

Given you live in the NE with the attendant cold, I am pulling for it just being the battery. Especially considering you had a low battery message. Looking at the records, do you see where/when the battery was last replaced? Just go to Autozone or one of those type of places and have the battery tested.

sp16

It's a 2007, no paperwork to indicate battery change, maybe I should look at the battery itself for a date... could be original?!?

So even though the car seems to crank quickly etc. could it still be just not quite powerful enough to start?

I will get the battery checked... just wonder why Lexus said could be crankshaft position sensor!

Junglequac

Well, it could be... That said, the service dept and used cars are what keeps the lights on at dealerships on the whole.

comotiger

The service department is planning ahead for their summer cruise vacation

Just kidding....I agree with Jungle. Hopefully it is an easy fix.

Congrats on your new car and welcome to CL. Despite this little hiccup, I expect you will enjoy many miles and years of sheer driving pleasure!

sp16

Thanks for all the help - I'm loving the car and the delightful black leather interior, this is just an annoyance that it would be nice to fix... loving the floating on air feeling and effortless power... just wish it would start first time every time

dlbuckls10

I had a similar problem last week and it was a weak battery.

Doublebase

I had this issue for three days...don't really know why, but it went away as quickly as it came. Some people suggested the fuel pump was going bad, others suggested it was bad fuel. I knew it wasn't my battery because it was relatively new. I suppose it could be a crank sensor on its way out as well.

roadfrog

It's not the battery if it turns over. Crankshaft sensor sounds plausible, but my guess is fuel related - pump etc. Easy enough to diagnose with a fuel pressure gauge, which you could borrow from your local lend a tool program.

sp16

I started her 4 times today within about 2 cranks... maybe it's gradually getting better as the car is being driven 30 miles per day now rather than standing in a forecourt....battery is getting a good daily charge.....or maybe I'm just doing a spot of wishful thinking - time will tell!

Thanks for all the advice - Crankshaft position sensor seems cheap and might be a sensible first step if it starts playing up again. Hope it doesn't turn out to be fuel pump related.

After saying in my earlier post that the RPM needle is rock steady, on real close scrutiny today I'm sure I saw it waver very very slight when I was sitting in traffic, don't think I can feel any lumpiness/misfiring but it's hard to say as the motor is so smooth... if it was the crank sensor going out of spec I have a feeling it there might be other noticeable symptoms?

sp16

So this morning it started no problem, drove 15 miles to work, parked, stopped the engine and got out then decided it wasn't parked well and went to start it. It took 5 cranks and only just caught on first button press. Later, I went to drive home, again it struggled to catch - when it did start, the revs seemed high at about 1500, then they rose by themselves to 1800 and sat revving high. When I engaged drive it dropped to normal ~650rpm tick over.

any ideas appreciated!

roadfrog

Well as I said earlier, we know it's not the battery. I would rule out fuel as well. While that doesn't necessarily leave the crankshaft/cam position sensor as the sole culprit, it certainly narrows things down. What I would do is allow Toyota or Lexus to hookup Techstream while driving the car to see what's up. I'm surprised that there are no codes stored in the system.

sp16

Yeah I thought the fuel pump could be ruled out too as after leaving it only a few seconds it wouldn't have had time to lose pressure in the line.

I too am surprised there are no codes yet... maybe that's just around the corner if it continues to act up!