Limp mode then sudden engine off on highway (1 Viewer)

[Chases Elk]

Last weekend I was stranded and needed a tow home when my 2006 LX470 went into limp mode (CEL slow flash, VSC Track, VSC off). In about the 10-20 seconds after noticing the lights, I turned on hazards and made it to the side of the road just as all power turned off. Sketchy.
This is after about a 5 hour drive, mostly using cruise control. I had just sped up, noticed the RPMs over 4, took foot off gas and felt a weird hesitation, then limp mode began. As I was pulling over, and the engine dying, there was a kind of flapping noise and a strange smell. Engine oil is fine.

The day before we'd noticed a lack of power when applying gas pedal, barely, but noticeable, and inconsistent.
On the side of the road, turning key turned on dash lights, but absolutely nothing else; no clicks from engine bay, no nothing.
Checked battery once home, finding 12.7 V, and took a charge to 13.4 before going back to 12.7 and staying there.
My code reader says 'failure to connect', which is weird since I've used it many times on this rig. So, I don't have any codes yet.

2 months ago I changed out the master cylinder due to booster pump motor dying, so I checked all connections and grounds and fuses and wires and found nothing out of the usual.

I'm mystified how to diagnose the issue, and can't find anything similar in searches. The only action I can think of to take now is to disconnect each wire connector one at a time to see if the reader will communicate with OBD system.

I'd appreciate any info from the community, thank you.

 

[Trunk Monkey]

I'd check that the wire that provides power to the OBD port has 12v coming to it and out of the port.

 

[Chases Elk]

I'd check that the wire that provides power to the OBD port has 12v coming to it and out of the port.

Thank you! Will do.

 

[GOLIGHTLY]

As @Trunk Monkey said, check your powers and grounds at OBD and ECU. A faulty MAF sensor can present similar symptoms, worth looking at. Unplugging that should default the ECU to a preset fuel air mixture and might get you out of limp mode (at least, worked on a 2011 F150).

Good luck man, let us know what you find.

 

[excessive]

+1 for checking grounds - remove , clean/ sand, re-attach, clean and re-tighten battery terminals,

 

[Chases Elk]

When charging the battery, the smart meter display fluctuates by a half volt. I can hear something cycling near the pedals.

I haven't solved anything else for now, and I think I'll take it in.

Thanks for the suggestions, I'll update once solved.

 

[OEMGUY0720]

If you don’t get any codes this could be a case of the 06/07 infamous fuel pump failure. What was the registered outside temperature when this happened and the mileage of the Lx?

Part # 950-0210 Denso Fuel pump

 

[2001LC]

Make sure no debris or bent leads in code reader.

 

[Chases Elk]

If you don’t get any codes this could be a case of the 06/07 infamous fuel pump failure. What was the registered outside temperature when this happened and the mileage of the Lx?

Part # 950-0210 Denso Fuel pump

Outside temp 55 F ish, mileage 170,000 ish

 

[birch hill]

Bad alternator?

 

[OEMGUY0720]

Outside temp 55 F ish, mileage 170,000 ish

Got you. Normally the indicative symptom is when outside temps are 95°F and higher, that’s when the 06/07 stalling happens (dying fuel pump). Would also suggest to get the fuel filter replaced (inexpensive part).

Stalling/sputtering can also be attributed to failed spark plugs and/or coil packs (hairline crack/s), you can check that as well.

 

[elk]

+1, check the fuel pump. There is a thread for checking pressure at the fuel rail. Call it a hunch, but you probably noticed a lack of power going up certain hills as well.

 

[2001LC]

06/07 fuel pump failure, in most cases. Happens most often during warmer OAT temperatures. It happens after running engine at higher RPM, then letting off gas pedal. As RPM drops, fuel pump fails. Engine dies. Typical no CEL, but very often 2 pending DTC (lean bk 1 & 2) if one checks for codes at that moment. Parking engine off for 5 to 20 min., and engine starts back up running/driving normal again.

 

[Sean Monett]

Mine did the exact same thing about 4 months ago. Some advice on here led to a ‘zero-point calibration’.
Did that at the dealership and it has not returned.

 

[Chases Elk]

Update: towed the LX to a mechanic referred to me by a local cruiser specialist. Shop reports totally damaged #6 cylinder spark plug hole, no threads, melted coilpack, and recommends total engine swap. They won't rebuild this one.
I missed that damage when I went over the car, but I didn't remove every plug wire since I was focused on the battery and fusible link, main fuse block, and the computer stuff inside the firewall.
My experience with 4Runners, Suburbans and Ford trucks is that even if a plug was burnt, the car would try to start. Second time this car just won't move with a failed system, brake master (booster motor issue) being the other one. I have limped home in old ford trucks with a shot master. I've limped home in the 4runner with a blown plug. This 06 LX's put me dead on the side of the highway twice now, more than any other rig I've had. Just sayin.

I'm a 1-2 banana mechanic anymore, so after replacing my master cylinder a couple months ago, I swore I was taking it in "next time". Here we are. And the shop gave me worst case scenario and a $9000 quote. Damn.

Diagnosing the early death, and I can only say that my lead foot combined with a few late oil changes is all I can put my finger on. Don't know, but I'm throwing in the blue towels on this one.
Thanks for chiming in and trying to help.

 

[Chases Elk]

06/07 fuel pump failure, in most cases. Happens most often during warmer OAT temperatures. It happens after running engine at higher RPM, then letting off gas pedal. As RPM drops, fuel pump fails. Engine dies. Typical no CEL, but very often 2 pending DTC (lean bk 1 & 2) if one checks for codes at that moment. Parking engine off for 5 to 20 min., and engine starts back up running/driving normal again.

So it fails temporarily, as it starts up again? But implies that you should replace it ASAP?
Thx

 

[2001LC]

Update: towed the LX to a mechanic referred to me by a local cruiser specialist. Shop reports totally damaged #6 cylinder spark plug hole, no threads, melted coilpack, and recommends total engine swap. They won't rebuild this one.
I missed that damage when I went over the car, but I didn't remove every plug wire since I was focused on the battery and fusible link, main fuse block, and the computer stuff inside the firewall.
My experience with 4Runners, Suburbans and Ford trucks is that even if a plug was burnt, the car would try to start. Second time this car just won't move with a failed system, brake master (booster motor issue) being the other one. I have limped home in old ford trucks with a shot master. I've limped home in the 4runner with a blown plug. This 06 LX's put me dead on the side of the highway twice now, more than any other rig I've had. Just sayin.

I'm a 1-2 banana mechanic anymore, so after replacing my master cylinder a couple months ago, I swore I was taking it in "next time". Here we are. And the shop gave me worst case scenario and a $9000 quote. Damn.

Diagnosing the early death, and I can only say that my lead foot combined with a few late oil changes is all I can put my finger on. Don't know, but I'm throwing in the blue towels on this one.
Thanks for chiming in and trying to help.

Ticking time bomb TICK TICK TICK: Spark plugs Alert Alert Alert!

TICK TICK TICK POP POP POP is a ticking time bomb, often mistaken as exhaust manifold crack or gasket leak leak. ALERT, ALERT, ALERT: Spark plugs are working themselves loose. "Walking Out" Then blowing out of head, taking their female threads of head with them! Very damaging! You think TICK...

forum.ih8mud.com

So it fails temporarily, as it starts up again? But implies that you should replace it ASAP?
Thx

Yes. If the classic symptoms. But they'll most times (knock on wood) start back up, after short cool down.

 

[YotaWagon]

Got you. Normally the indicative symptom is when outside temps are 95°F and higher, that’s when the 06/07 stalling happens (dying fuel pump). Would also suggest to get the fuel filter replaced (inexpensive part).

Stalling/sputtering can also be attributed to failed spark plugs and/or coil packs (hairline crack/s), you can check that as well.

Thanks for this tip about the spark plugs/coil packs. I know I'm not OP, but I've had 2 instances of stalling at speeds under 15 mph, and 3-4 other instances of the car acting like it might stall for a split second when at highway speed (although in my case unlike OP, no limp mode, just straight up stalled out). I changed fuel filter, fuel pump, cleaned battery terminals (new-ish batter), checked all the grounds I could find, ... and maybe a few other things. Nothing helped, it would happen again the next month. The only constant I could think of was hot weather and A/C on.

Anyway, you've given me another possible culprit. Thanks.