Hi... new here,
I have been searching the forums for an answer to this problem I am having with my 2000 4.6L truck. I haven't had any luck, so I am hoping someone here might be able to point me in the right direction.

When the outside temps fall below about 40deg F, I have to rev the engine a little (approx 2100 rpm) in order to get the transmission to shift from park into reverse. If I don't do this, it bogs the engine down and the motor dies.

Once I am in gear, everything works normally. I have no codes or lights. I have tried a new IAC valve, checked and replaced the trans fluid and filter. This is a very strange issue to be having. It SEEMS like it might have something to do with fluid flow? Like maybe the transmission cooler is plugged partially?

Any help would be greatly appreciated!!

 

Hi have you checked the trans fluid for level and color? How many miles on your rig? Is the trans overdue for service?

 

208,000 miles. Yes, I have replaced (in the last 6months) the transmission fluid in its entirety. The issue was happening prior to the fluid change, so it wasn't something I did.

 

I am thinking your engine is running way too lean, maybe need to check that out.
you may need to check if there are any error codes with a reader and go from there.
So other than the cold issue, all seems normal right?

 

How could a lean mixture affect the reverse engagement? That's about the wildest theory I've heard.

You either have low fluid or a worn transmission.

 

Maybe I didn't do a good job describing it.
When the outside air temperature is below roughly 40deg F (and the engine is cold, hasn't been running in 24hrs), if I don't rev the engine the motor will bog down and die when I shift from park to reverse. And the colder the temperature, the worse the symptoms.
Once it is in gear (reverse in this case) everything works normally.
The fluid is new and at the proper level.
The IAC valve is new.
I am wondering if it might be the Torque Converter Clutch solenoid OR a restriction in the flow of ATF through the cooler.
Would a fluid restriction in the cooler CAUSE symptoms similar to this? I have found some sources that say it would. I am wondering if anyone here has had a similar issue and what the cause was.