4l80e Temperature Surge After Idling?

[JohnsHummer]

My transmission shifts and otherwise operates OK. I'm measuring the oil temperature between the transmission and the cooler.

 

I know that's hot oil as compared to the pan; however, the temperature spikes are new.

 

That temperature runs between 150 ~ 175 degrees. If I idle while in DRIVE, for 5 minutes, the temperature doesn't change. But immediately (5 seconds) after taking off the temperature spikes to 300 degrees. Drive around for 5 minutes it will come down to 225. Drive with convertor locked, it will drop back to 150 degree in 2 minutes.

 

 

I'm no expert; I'm just checking everything I can think of. Strange that the flow drops so much in Drive and that the oil temperature does not change when idling.

 

- Idle in PARK or NEUTRAL, the temperature may rise 25 degrees (instead of 150) and not rise when taking off

 

-No codes. Oil is clean. Level is correct. Filter & drain+fill was done within 300 miles (I don't drive it much). Bypass valve is OK (oil is not bypassing the cooler).

 

-Oil flow is 1 gpm @ 50 psi at transmission when in PARK & NEUTRAL.

-Oil flow drops to 0.3 gpm @ 15 psi when in DRIVE and idling. Why???????

 

-Control pressures tests indicate pressure to be 10 psi high at each amperage setting.

-Wiring is OK. I physically verified commanded current going to the PC solenoid to be accurate.

-PCM is commanding 90 psi while idling in drive. Actual pressure = 100. Those seem high.

 

Any ideas? Is the reduced flow and 150 degree spike normal? What else can I check or change? Is this a real problem?

[JohnsHummer]

Been working at this some more. Ignoring the previous details and temperatures, the symptoms are simple;

 

at 700 rpm IDLE;

 

- there's nearly no flow out of transmission in DRIVE

pressure out of transmission = 6 psi

pressure in to transmission = 3 psi

 

-there's 1 gpm flow in PARK, NEUTRAL, REVERSE

pressure out of transmission = 40 psi

pressure in to transmission = 30 psi

 

 

at 1800 rpm moving in DRIVE;

 

pressure out of transmission = 40 ~ 80 psi

pressure in to transmission = 30 ~ 70 psi

 

 

It's not the TCC solenoid or PC solenoid or the bypass valve.

 

Any ideas?