2012 Yukon XL Denali with 6.2 engine. Low oil pressure, low RPM in drive and idling.

[testdepth]

2012 Yukon XL Denali with 6.2 engine. Low oil pressure, low RPM in drive and idling. Truck engine shut off on my wife twice this week while driving.

No check engine light and no DTCs at all. Engine cylinders not missing. No weird sounds.
While sitting at idle in park the oil pressure was 10 to 15. While sitting in drive at a stop sign or light it was the same.
Oil pressure on the road 20 or less most of the time.
I test drove her truck multiple times and it never shutoff on me.
Today I flushed the engine and changed the oil and filter. Added new Dexos full sunthetic and AC Delco filter.
Swapped out the 13yr old crank shaft sensor.
Put it all back together and drove it.
No DTCs or check engine light. Oil pressure sitting in drive at the light with 18psi and on the road was around 38psi.

My RPMs stopped in drive at the light 500 RPM. This seems low is it?

 

[rdezs]

CASE relearn completed?

 

[Marky Dissod]

Crank sensor's got nothing to do with this.
Clean or replace oil pressure sensor and neighboring screen/filter thingy, oil pressure will most likely improve.
May want to switch to Group4 synthetic 0W30/5W30.

How many miles? Lots of city / stop'n'go, or highway, or what?

 

[Fless]

When was the throttle body last cleaned? If not recently, consider a thorough cleaning.

A scan tool with live data will tell you the 1) actual idle rpm and 2) desired idle rpm. Compare.

And as @rdezs asked, have a CASE relearn done with a capable scanner any time the crank sensor or the cam sensor is changed.

 

[rdezs]

I had to read it again and realized the engine flush resulted in oil pressure coming back to 38 PSI while driving.... I'm inclined to think the flesh freed up the oil pump pressure relief valve, was probably gummed up with crap. Assuming it still has the AFM and VVT on that L94? Both systems are heavily dependent on very clean oil and proper pressure. You may in fact have solved the problem for now.... More frequent oil changes are in order. That filter screen under the oil pressure sending unit should probably be pulled and replaced.

Idle speed sounds a little low. Our 2014 idles at 550 RPM. As mentioned earlier it's probably due for a throttle body cleaning...

 

[rockola1971]

Never assume ANY of our generation of gauges are correct. They arent most reliable GM clusters in the world!

 

[rdezs]

Never assume ANY of our generation of gauges are correct. They arent most reliable GM clusters in the world!

Correct in general. But going from consistently low readings, and followed by a flush the readings return to fairly normal.... I don't think that's a coincidence.

I would guess the guys engine is probably due for some maintenance items. Like Fless mentioned, the throttle body cleaning. I'd also probably want to drop the oil pan, replace the pickup tube o-ring and clean the sludge out of the bottom of the oil pan. Those engine flush additives can leave a lot in the bottom of the sump... And due to the age, that pick up tube o-ring is passed its life expectancy.

 

[testdepth]

Crank sensor's got nothing to do with this.
Clean or replace oil pressure sensor and neighboring screen/filter thingy, oil pressure will most likely improve.
May want to switch to Group4 synthetic 0W30/5W30.

How many miles? Lots of city / stop'n'go, or highway, or what?

179000 miles on it and already replaced the sensor and filter for it once due to sensor going bad. May need to again?

 

[testdepth]

When was the throttle body last cleaned? If not recently, consider a thorough cleaning.

A scan tool with live data will tell you the 1) actual idle rpm and 2) desired idle rpm. Compare.

And as @rdezs asked, have a CASE relearn done with a capable scanner any time the crank sensor or the cam sensor is changed.

What is a CASE relearn?
Throttle body is brand new.

 

[Marky Dissod]

What is a CASE relearn?

Crank Angle Sensor Error relearn.

 

[Fless]

Crank Angle Sensor Error relearn.

No fair! You used Google....

 

[Marky Dissod]

No fair! You used Google ...

Intermediate Tuner's Glossary. Old enough that every time I use DuckDuckGo (googl? Please), I die a lil inside.

 

[Fless]

Intermediate Tuner's Glossary. Old enough that every time I use DuckDuckGo (googl? Please), I die a lil inside.

"Google" is the Kleenex of search engines. I use Puffs and DDG.

 

[Marky Dissod]

Wouldn't be surprised if googl is no better than AskJeeves in 5-7 years.