off throttle dying after tranny swap...

[Superado]

when stopping at a light or such...rpms drop below idle and cuts off
when slowing down and off throttle to make a turn...rpms drop below idle and cuts off...
had this issue after new motor, but finally got it to stop w/ alot of idle tune suggestions I read here...
then broke 4L60e again and replaced w/ 4L80e and slightly higher stall...
and it's doing this again...appears to peg lean each time this happens...
any ideas?

[Superado]

also...if I catch it before it cuts off and give it a little gas...it richens back up, rpms rise back to set idle and will sit and idle as long as I want...???

[joecar]

Sounds like a engine tune problem... (I'll delete the duplicate posts).

[joecar]

Did you check that all the grounds are still ok and that no wires got pinched between motor and trans...?

Did you check that the vacuum lines are all still ok and attached...?

[Superado]

yep...
only does it in-gear while slowing down to a stop or right after stopping...

[jfpilla]

With a higher stall converter you have less engine braking. That causes faster decrease of RPMs and often overshooting of the targeted RPMs.
As a test, increase your RPMs. If that helps then it's likely you need to redo the throttle cracker.
I found it a lot easier to turn on the TC at 24mph and off at 23mph raise the RPMs by 50. Lazy maybe but it works great with not a hint of surge or hunting.

[Superado]

I'll give that a shot...THANK YOU VERY MUCH!

[joecar]

Makes sense.

[Superado]

changed throttle cracker to 24 on and 23 off...
increased all desired idle rpms by 50...
helped a little, especially on turns...but still dropping below desired rpm...searching, surging, lean, rich, lean...cutting off
all of this at stops and when making 90° + turns

[joecar]

Post some logs when you can (I already have your tune file from the other thread).