mowrey96

I have a Vigilante 3600 Torque Converter (thanx TBYRNE!). I had it installed and the car was dyno-tuned. I haven’t had time to bring it back to have it tweaked, but I will. I am trying to self-diagnose the problem. When I punch the throttle and let off quickly, the rpm’s drop to between 200-600 rpm’s. Occasionally it stalls. This sucks in traffic. Could this be related to the torque converter? In a manual transmission, the flywheels inertia keeps the engine from stalling. What keeps an automatic from stalling (nothing, in my case)? I guess it may just need to be tweaked on the dyno, but I thought I would throw it out there to see if anyone has any ideas.

Mod’s:
99 Coupe
Automatic
Vigilante 3600
Head and Cam package
Vararam
Ported TB
78mm Fast Intake
Long Tube Headers
GHL Exhaust

gojo

A couple of questions.
Was the converter the only change made before the RPMs began to overshoot idle?
If you give it a little gas off idle, will the car cruise slightly on it's own?

Your setup with an A4 is touchy with a high stall converter and usually takes a few flashes to get it right.

mowrey96

I did the Fast Intake at the same time as the TC. The car will move slightly on its own from a little gas off idle. You think it will just need another trip or two to the dyno?

gojo

If it does it when in gear and in p/n then the tuner may need to raise RAFs at warm temps a little at a time. Like .01. This is what I would try first. If it only does it in gear the Airflow Decay in Gear might do it. Try lowering the values by 50% from the mph at which it happens and down.

XPC5R

It's a tuning problem, the smaller diameter converter as less flywheel effect, and lets the revs drop too quick.

The tables to tweak are the airflow decay in gear. Not sure about on a C5 fly by wire throttle, but on an F-body tune the direction to go is reduce the values by about 20-40%. That slows the rpm fall when you let off the throttle. It may be opposite fo the C5 throttle, but it's a quick test.