FAST Classic seq

Tom Shea

Registered User
I posted this on also. No replies yet. I guess I should have put it in the form of a question. I am finally getting around to tuning my car. It seems like there has always been something pre-emting this for over 10 years. I'm now at the point where I really don't care. I noticed that the engine seems to like 11.5 to 12.5 A/F idle in park. When I put it in gear it goes up one to two full points in the A/F. This results in the A/F being at 12.5 to 13.5. It wants to stall at much leaner, and the throttle response is not good. I do have both the AE tables starting out at the left hand side of the screen at around 1/2 way up. This is not something I have seen on the few other GCTs I have looked at. It does seem to work and it does not affect the A/F until actuated by either throttle or MAP. I do notice some fuel smoke when idling both in and out of gear. If I lean it out enough to avoid this, the A/F slowly climbs to 15.94/1, so I have no Idea how lean it really is since that is the leanest that this box shows. I am not idling in closed loop. At least not yet. It seems like the A/F at idle is rich and I can smell the unburnt fuel as well as see the smoke, but I can't get it to run well when I lean it out. Maybe there is a physical problem like a sneaky vacuum leak, although I checked and didn't find any. Maybe the 269/264 (218/212@.050) cam and the max ported heads are partially to blame. Fresh engine 274 CID, M&A heads, 84lb injs, FAST classic seq box.


Registered User
Staff member
Your VE table is probably off. Leave the AFR table alone and focus on getting the VE table correct before modifying the AFR table. 12.5-13.5 should be fine for off idle/driving. 11.5 is rich at idle. If you get your VE table close and smooth out the bumps in the graph it should improve. The classic FAST WBO2 control is not as fast as newer units so it can be tricky getting it right especially in closed loop.

Bryan C.

Senior Member
Staff member
Thanks Chris.

Look Ty, real tech. I bet it made you throw up a little when you saw it. :icon16: