So I got my fti 3800 triple disc put in and I thought all was well. I finally got the fluid level right and now the car sometimes stalls if I put it in reverse. Didnt have any issues before the converter went in. Think its tune related or something else? Car was tuned for a fti3800 single disc, it came out due to failure, a cheap proking remanned converter went in, it was 100% fine then this triple disc went in. This morning I started the car, it idled for a few minutes, put it in reverse and it died. Started it back up, put it in reverse and it was good. Its done this a few times since the triple disc went in.

Where would you start?

 

100% guess here but I would think tune related due to the little extra rotational weight with the converter combined with the very long transmission gear ratio of reverse.
1st gear 3.06
Reverse 2.29

 

tune related.
auto cars always have a little more load in reverse and need tuned accordingly.
Big cams highlight this

 

IF it is the converter it will do it on forward gears as well. Otherwise sounds tune related like mentioned above.

 

Now you have me curious too. Other than bumping the idle speed and adjusting the throttle blade so that you need zero IAC when warm, I'm not aware of other tuning solutions.
Like you said, big cams make this worse. I have had cold-stalling problems with various cams in the 239/251 range, with and without MAF, different intakes, different TBs, DBW and DBC, 411 PCM, Dominator ECM and more.
Since O2 sensors tend to read leaner that it really is with big cams, I do find that an "apparent" lean idle reduces stalling.

OP: What are your cam specs and other engine mods?

 

I agree, We put a decent cam in my son in-laws 6.0 4l80e combo and it only stalled in reverse after you let off the throttle. After doing some research I found several articles that state line pressure is higher in reverse. So I assume that would put more load on the pump/ converter. We're running Holley efi so slowing the rate it returns to idle after you let off the gas is the fix in our case.

 

I wonder why it wasn't a problem with the temporary converter. Same reverse line pressures.

OP says it was tuned for the FTI converter. Did it work properly after the tune and before the problem with the first FTI converter?

 

Yea it just does it in reverse.

cam is a ws6 hotcam . 218/226(?) .600/.600.

i think the tune is not anything useful the more I think about it. Since it wasn’t locking up I think the tune was done wrong due to the computer doing things it shouldn’t (boosting line psi to compensate for seeing slippage). I will talk to my tuner about a retune

 

This is a very modest cam which shouldn't cause major tuning problems.
Verify that the tuner has set a very modest and identical amount of ignition advance between 400 and 1000 rpm at the cylinder airmass where the engine idles. I've seen plenty of tunes where the ignition advance increases from 400 RPM on. But then as the engine begins to stall, ignition advance goes down which slows the engine even more; this negative feedback then leads to a stall. Also by having a modest amount of ignition advance (e.g. 10 degrees) the "Underspeed" advance adjustment can increase the engine speed to reduce the chance of a stall.
The "High Octane", and under Idle Spark Advance the "In Drive" and "In Park" tables all need to be in agreement.