LX470 Dying When Turning the Steering Wheel at Low RPM (1 Viewer)

[Grant LX470]

Hello, this is my first post so please forgive me if there are any issues. I am having an odd issue with my vehicle occasionally dying out at low RPM when I turn the steering wheel, and I am hoping someone may be able to give me some suggestions. I also have very limited mechanical knowledge, which is likely evident.
Link: Problem Video Link

Context:

I have a 2004 LX470 with around 165k miles. It has just been engine swapped with a motor with around 130k miles from a 2003 tundra. Lexus told me the previous motor was destroyed as a result of a "throttle body relief plug failure", which is something I am not familiar with.

After about 3 hours of driving the other day, the car died as I was trying to turn into a Walmart parking lot, but I was able to start it back up via jump start. I believe the battery was bad, so I replaced it while I was stranded at the Walmart. The vehicle appeared to drive fine afterwards and I got the alternator tested, with everything checking out. After about 30 more minutes of driving, I stopped at a gas station to get ice. When leaving, the car started up fine, but when I began turning the wheel to back out, the car died (just like in video link). I learned I could overcome the stall by holding the car at around 2,000 or 2,500 RPM (it would still initially stutter and try to die, but enough gas would prevent power loss). I was able to drive 30 more minutes to a nearby auto shop as long as I kept the RPM high when turning at low speed. Of course, the car decided to stop acting up the whole time the auto shop had it, and they couldn't find any issues. The only code it is throwing is related to an oxygen sensor. The car once again drove fine for the next hour (I assumed it was a fluke), but I encountered the issue again when trying to leave a different Walmart parking lot (some sort of Walmart curse?).

What I have tried so far:
- Battery replacement
- Siphoning out the old, discolored power steering fluid and replacing it with Dex/Merc ATF.
- Threw some Seafoam in (figured it wouldn't hurt)

Next Step:
- Based on reading some things in this forum, I think it may be worth trying to clean the throttle body. Hopefully I can do so without breaking anything!

Any advice or suggestions would be greatly appreciated, thank you.

 

[Bisho]

There is an idle up valve on the back of the power steering pump, its intended to have the truck idle up when you turn the wheel at low rpms. Yours may be failed. I haven't heard of this causing the truck to die in the past, usually folks just have harder steering at low rpm, but you never know.

 

[Grant LX470]

There is an idle up valve on the back of the power steering pump, its intended to have the truck idle up when you turn the wheel at low rpms. Yours may be failed. I haven't heard of this causing the truck to die in the past, usually folks just have harder steering at low rpm, but you never know.
View attachment 3865525

Thanks for the reply, I will look into it! It's also weird because the steering does not seem to be any tougher than normal at any point, even at low RPM.

 

[2001LC]

My first though: Idle up (@Bisho suggested) or vacuum lines from/to it. But if engine dies that easy. You also have, more going on that needs servicing.

You also have warring VSC off warning lights. In some cases. When idle up vacuum line off. We do get a check engine light (CEL). Which would shut down ABS, We then see waring VSC OFF.

You can check the vacuum lines. Just remove the engine cover and look. One that is very often left off. Is one from idle up to air pipe.

Two vacuum lines are attached to the Idle up control valve on/attached to power steering (PS) pump (AKA vane pump).

If all vacuum lines connected and good sung fit. Here's, idle up tested.

Sometimes a failed idle up, leak PS (ATF) fluid. The PS system pressure and engine vacuum. Suck ATF into engine. Signs of this would be:
ATF in vacuum line.
ATF in throttle body.
Tail pipe smoke.
Tail pipe smoke

 

[Grant LX470]

My first though: Idle up (@Bisho suggested) or vacuum lines from/to it. But if engine dies that easy. You also have, more going on that needs servicing.

You also have warring VSC off warning lights. In some cases. When idle up vacuum line off. We do get a check engine light (CEL). Which would shut down ABS, We then see waring VSC OFF.

You can check the vacuum lines. Just remove the engine cover and look. One that is very often left off. Is one from idle up to air pipe.
View attachment 3866063
Two vacuum lines are attached to the Idle up control valve on/attached to power steering (PS) pump (AKA vane pump).
View attachment 3866064

If all vacuum lines connected and good sung fit. Here's, idle up tested.
View attachment 3866066
Sometimes a failed idle up, leak PS (ATF) fluid. The PS system pressure and engine vacuum. Suck ATF into engine. Signs of this would be:
ATF in vacuum line.
ATF in throttle body.
Tail pipe smoke.
Tail pipe smoke

This is very helpful, especially the example photos! Thank you.

 

[Grant LX470]

@Bisho @2001LC

Hoses and connections look pretty decent to me, although the throttle up valve doesn't look great:

This weekend I plan to:
- Replace throttle up valve
- Clean throttle body
- Clean MAF sensor
- Replace engine air filter

Hopefully something will resolve the issue. At the very least, I've learned a lot, thanks guys!

 

[2001LC]

I start by inspecting & test idle up control valve. Test good, no need to replace.

Before MAF cleaning.
Make sure to disconnect negative battery clamp frist. Reconnect last.