Trying to figure an issue with my 99K3500/454/4L80E. Ever since I have owned this truck after it warms up for a bit it will want to, and has died. Normally does it when in reverse but has done it in forward. I'll stop at a stop sign and the truck will idle fine then idle down to the point of dieing unless I left off the brake or pop the truck into N. When it's in reverse, it happens just as I've started the truck up with my foot on the brake or shifting from D to R and start to move. The way it acts reminds me of a person letting off the clutch and taking off in a manual transmission. It's not consistent and it's not throwing any codes. My mechanic first suggested the EGR valve so I replaced that. Next we tried the IAC because it was showing a weird signal on his scan tool. Same thing. Just replaced the upper plenum gaskets due to them leaking, creating a vacuum leak thinking that may have been the culprit. Same problem. He said that maybe the TC is acting up. I don't know enough about those to have a guess as to that may be what it is. The tranny doesn't have any unusual noises or doesn't feel like it's slipping. We are both at a loss as to what may be causing it.
Torque converter issues??
- Thread starter WillB
- Start date
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Sounds about the same as the issue I commented on here:
https://www.gmt400.com/threads/4l80e-trans-twerk.50260/#post-1115912
Basically the TCC is engaging at low RPM due to low fluid flow. There's several things that can cause it like a plugged trans cooler line or heat exchanger. In my case it was a worn actuator feed limit, line to lube valve as well as the cap on the reverse boost valve.
I would first inspect the transmission oil lines for damage kinks. Perhaps try to flush the trans coolers. But more than likely it's these worn valves in the valve body and pump housing.
I talk about my stalling problems on page 10+ of my build thread:
https://www.gmt400.com/threads/andy’s-1995-cclb-7-4l-tbi-to-vortec-swap.45295/page-10
https://www.gmt400.com/threads/4l80e-trans-twerk.50260/#post-1115912
Basically the TCC is engaging at low RPM due to low fluid flow. There's several things that can cause it like a plugged trans cooler line or heat exchanger. In my case it was a worn actuator feed limit, line to lube valve as well as the cap on the reverse boost valve.
I would first inspect the transmission oil lines for damage kinks. Perhaps try to flush the trans coolers. But more than likely it's these worn valves in the valve body and pump housing.
I talk about my stalling problems on page 10+ of my build thread:
https://www.gmt400.com/threads/andy’s-1995-cclb-7-4l-tbi-to-vortec-swap.45295/page-10
