sixonemale

I have a 2006 SC430 with about 27,000 miles. The other day while my wife was driving it when it stalled while she was accelerating. She then tried to start it up in Park, and it would start, but then when she put it in Drive it stalled, again and again. I actually arrived where she was stalled and it did the same thing to me. Long-story short I had it towed on a flat bed to a local Lexus dealer. My first thought was that it may be a throttle control valve, or some sort of electronic sensor that has malfunctioned, or even the remote possibility of it being battery, though not a logical thought because it did turn over and start. The Lexus dealer could not find any codes of any sort and the battery as expected checked out fine. They are having a difficult time diagnosing what appears to be a very intermittent problem and have not ruled anything out but the battery thus far. They have only experienced the problem of the car not starting just once, it has since started and run fine for them over the past couple of days. They are now looking at the fuel delivery system, fuel pump, etc.

If anyone has any ideas, it would be great to hear suggestions, especially if you have experienced a similar problem.

Thanks in advance!

VVTiBob

Throttle body and MAF (Mass Air Flow) sensor .... see this thread https://www.clublexus.com/forums/sc-...on-vortex.html Surprised it didn't throw a trouble code though....

sixonemale

Thanks Bob, I had already thought of the MAF, but did not think that was the problem because the idle was never rough, it was always smooth which lead me to believe that it was not the problem.

sixonemale

I made the suggestion of the MAF to Lexus, but like you stated, they don't think it's the problem because it did not throw a trouble code.

The dealer is currently leaning toward the fuel pump being the problem.

scyul

Pretty sure it's not the pump... I've never seen one fail...

I'd change the MAF even if you get no trouble code. It happened to me on a Subaru.

Try gently tapping on the MAF with a small wrench, with engine idleling to see if you notice any change in the rpm.

joezie

This is just a thought, I own an automotive repair bus.for last 34 yrs. We do work on Lexus, but haven't run into that problem on them. But it sounds to me the same problem we ran into on certain Oldsmobiles.The problem was the torque converter lock up solenoid.It would do the exact same thing that your describing when it was warm.they didn't set a code either.the solenoid would stick on & keep the torque converter locked and make the engine die. Once it unstuck the car was fine.Maybe ask your Lexus or Repair Shop about this. Good luck!

scdroptop

iTrader: (1)

My vote would be fuel related as well. The key to the story is when they put in drive it stalls while accelerating. May not be the FP but could it be the fuel filter is clogged?

I know it's WAY too premature for FF to fail, and we have not seen or heard of many problems with the FP, but it's possible with some bad gas or perhaps any additivies that might have been put in the car (don't know if you have ever done fuel injector treatment, etc perhaps) maybe something caused this to happen externally?

Some stories of first generation SC400 fuel filter causing similar stall/hesitation on acceleration is found here...but this is on a 95 with 188k miles!!!

http://us.lexusownersclub.com/forums...howtopic=53943

buddhi

This Mystery is happening to my 152K mile 2003. It's sitting until fixed - don't trust it to not die in the middle of the road as it did twice in one day a couple weeks ago.

Others have also had what appears to be the same intermittent problem.

It stalled while accelerating and died in the road after coasting to a stop. For two minutes it would not start, then it did and all was normal. Then again it did it and finally started and all was not normal - could barely get it home (more detail on that below). Or, as sixonemale wrote, "tried to start it up in Park, and it would start, but then when put it into Drive it stalled, again and again."

Seems to be a fairly common problem.

From the Gen 1 SC forum, it happens there too:
“Car can start, then 2-3 seconds later it dies, after a few tries she will idle, any ideas? The car has actually died twice just going down the road cruising along.”
“Ihaveexactlythesameproblem: my 95' SC400, 116kmiles starts, hits 1250-1500 rpm and then dies. many times after another. starts - dies - starts dies. it does NOT hold idle.”

“Ithas been starting right away butthen I couldn't press the gas and rev to 4k rpm, it would fall to about 2500 rpm and die shortly after. Another couple of tries and it worked fine. Could my fuel pump ecu be out?”

My experience:
It died in the road going about 40 and then coasted while in Drive to a stop - was apparently in neutral. All lights on dash on. It would not start for 2 minutes. Check engine light on, VSC on, VSC off all stayed on for a few minutes, then they all went off. Then it started but any gas would stall it. Got it started and feathered the gas to get the revs up to 1500 to keep it going, then put it into Drive and slowly drove off at 5 mph as it was trying to stall. I feathered the gas to keep it running trying to work the revs up, Then it would stall in 50 feet. I'd stop, Park, and do the procedure again. Occasionally I got 500 feet. Made it home that way, but not fun trying to cross an intersection.

Here are the possible causes I've gleaned from various threads:
MAF except no rough idle and maybe no P0100/31 error code, torque converter lock up solenoid sticks, fuel pump - these do not fail too often, throttle control valve, fuel filter, fuel ECU, ECT sensor, or fuses.

Another possibility from Coleroad: “ would check the wires and plugsfor all four wheel speed sensors. Then the sensors themselves for damage ordirt. Then I would check the tone ring for dirt or damage.

There seems to be no definitive solution. Any ideas?

Update: Mechanic found nothing and no codes. Since the upper radiator coolant outlet hose had twice slipped off and released coolant (some joker had sawed off the plastic lip that keeps the hose clamped on so I had to replace the radiator, did thermostat too), my mechanic guessed the lower coolant level and lack of pressure triggered a failsafe. Maybe, but not much coolant was lost either time. Got a new suspension and now need an alignment before test driving. Will also throw in some fuel additive and Shell VPower. I just changed the PCV valve.

More possibilities: gas cap, charcoal canister, disconnected evap hose near the oil filler tube (engine mounts?) but no code, EVAP system canister purge valve? Could the previously replaced water pump be bad?

Bgw70

could it be a vacuum leak?
I would remove the engine cover and look very closely at all the vacuum lines and hoses. Most SC430s your age will be broken. EASY
Next, read the codes if you have a code reader...might be a huge help. EASY
when was the last time you changed the timing belt, water pump, tensioner, etc? What you describe reminds me of the timing being off. DIFFICULT

buddhi

Good ideas and I appreciate them. Hope you are correct!
Will check for vacuum leaks.
But could that really stop a perfectly running car cold?
Engine was as smooth as butter under acceleration and idle.
Timing belt and the rest changed about 30K ago.
I'm also curious that it was in Drive, then died and switched to neutral
and coasted. Doesn't that seem like a programmed response kicking in,
like a bad ECU somewhere? Also, wouldn't a vacuum leak affect
the car more continuously? When running, the engine seems perfect.

Will be taking it to a guy who's supposed to be good and he'll check
the codes, but not sure they got stored according to people who've
had this problem with their cars.

jimisbell

sounds like fuel pump or relay. My LS did the same thing twice. No warning, just quit and would not restart.....until maybe an hour later and it restarted perfectly. The third time it didnt restart until we diagnosed the fuel pump and the relay BOTH. The pump was fried and the relay was welded shut. Dont know which came first, the chicken or the egg. But suspect the relay was acting up, welded shut and burned out the pump. Its an easy fix (dont have to drop the fuel tank) and the parts are under $200.

buddhi

Yes, fuel pump relay is a definite possibility. I will put it on the list I'm compiling for my mechanic to check.

Bgw70

those codes should be stored and hopefully they will still be there to provide additional info.
yes, if you have a bad vacuum leak, it will usually be there all the time especially when the engine is under a load. When in park, the computer may compensate and it can seem normal...

just to be clear, the dash lights, CEL and VSC will go out, the engine starts fine and it will drive normal, then it all goes down hill...is that correct?

buddhi

the first time it happened the dash lit up like a Christmas tree, all the lights, and then they all went off.
no lights stayed on. and the first time it died, it then started fine after a couple minutes and drove perfectly.

the second time, the lights all lit up like when you turn the key a notch, and then they all went off except
the VSC, the VSC off, and the check engine light. those three all stayed on for a while, and then they
all went off. no lights are on now when I start it. it starts perfectly now, just like normal and revs fine.

that second time it died it was more difficult to start and I had to lightly pump the gas up and down to
work the revs up so I could put it into drive to get it moving but it would barely go 5 or 10 miles per hour
on the verge of stalling and then die again. after 100 feet or so it would die and I have to repeat the
process. those three lights were on during this.

I'm really hoping some codes will be there but for some reason I don't think any will show up.

GmanSC

There is only two things that start the engine and keep it going: gas and electric. If you have gas in the chamber and your spark plugs fire, the engine should start. Any mechanic should be able to figure out your problem.