My 2012 Lexus ISF stalls when it is at an idle only after it has been driven hard or has had time to fully warm up (about 30-40min), no issues at cold start it starts completely fine every time and no loss of power at speed, no CEL once it stalls, i can start it back up but just wants to stall again if I dont hold the revs, will continue to stall at every stop light unless i have the engine off for a bit, but today was running fine for 40min then came to a parking lot shut off the car, started back up 20min later then it was stalling out, shut it off for another 5-10 min and then was compleltly fine and ran like normal for 15-20min until i got home and no stalling

 

What is your normal idle rpm?

Do you have your A/C enabled on your HVAC?

Does this happen at night with the lights on?

 

It happens at night with lights and A/C on and it happens during the day with no lights and no A/C on.

 

Is this a new development or has this been on-going?

What maintenance has been done recently?

 

It started happening this past month, today when i was driving it started happening and stalled at a stoplight, but i started the car up went to a parking lot with it still running while parked and nothing happned, then drove back home like normal, it almost stalled at the last stoplight before my house but somehow didnt and then i made it home.
Maintenance as of recently the last 1.5k miles
BGK44
Fuel Rail Pressure Sensor
New Fuel Filter
New Camshaft position sensor
New Direct Injection harness

 

Also I was thinking it could be the IACV may be gummed up but then I still question why it ONLY happens once engine is warm

 

This engine doesn't have an IACV. The throttleplate does it all.

What was the last maintenance before the problem started, and why did you get a new DI harness?

 

I just bought the car a month ago and the problem only started happening about a week or 2 after i bought it, so i'm not sure the the DI harness was done.

 

I do have an RR AOS on the car and when looking around the engine bay I did notice some oil sludge on one of the blue hoses coming out of the RR AOS, not sure it that might have anything to do with this?

 

Bypass the AOS to see if it is the problem. The connections on those devices present a risk of air leaks if they're not well connected, and owners here have had issues with these from time to time.

I don't have one of these of any kind on my car. If you are not tracking your car and have a decent build from the factory (good oil control ring fit), you really don't need a separator.

 

I removed the AOS and went for a 25-35min drive started happening right around the 30min mark and my car stalled at a light, turned it back on and started driving, then after that one stall on my way home it didn't stall again for the 5 min drive back home until I got to my driveway which is when it stalled out again, started it right back up and had it running for another 5 min and no stall. Still no CEL the only warning i get on my dash at all is "High Transmission Fluid Temp." but that wouldnt make sense since the car drives fine once i get it started again, i have no loss of power at speed, and sometimes after i start it back up it doesnt stall again.

 

Could this possibly be a camshaft position sensor that got shorted somehow? If so, how many camshaft position sensors are on this engine?

 

That definitely sets a DTC. So does a problem with cam timing actuators. There are four cam sensors, one for each camshaft.

When you bypassed the AOS, did you just connect the hoses going to the can, or did you remove the hoses and put a straight hose between the PCV and the intake manifold, or just cap off the intake manifold and let the AOS vent to atmosphere?

 

I completely removed the AOS and put the hoses back to stock how they routing it back into the intake manifold, I used my buddy's scan tool and see that there is a stored code that comes up on the scanner for P0335 which is the crankshaft position sensor, so there is only one of the correct? And I was reading through other forums saying that it can only happen once the car is warmed up and would explain the intermittent stalling.

 

Not sure about the "only happen once the car is warmed up" but the test procedure for it is pretty straight forward, except the connector at the ECM isn't exactly easy to get to for the test. There is a connector at the ECM, an intermediate connector with three wires in and out, and the sensor itself which is actually pretty easy to replace comparatively speaking. Way easier than lots of other things we do all the time.