Hi guys, I'm going to be purchasing a programmer and setting up an ALDL cable in the next few weeks. I've downloaded TunerPro and a bunch of bin files to begin acquianting myself with all of the different parameters I can change. I have a custom memcal I had burned for my 4 speed manual 327 TPI conversion, just so I could get the car running and not be throwing check engine lights with egr deleted, etc. The car runs commendably in open loop mode -- it meets its target idle speed of 750 rpms, the idle is surprisingly good quality considering my long duration flat tappet hydraulic cam, and the car is very responsive. In closed loop, the car is doggy launching, the idle usually settles to around 1200 rpms (and the minimum air speed is adjusted to 600 rpms in closed loop, so this isn't the probem). The biggest problem in closed loop is that when you rev the car and let completely off the gas, the revs fall pretty slowly -- slowly enough that when I let off the gas to shift, I barely drop 1000 rpms before I'm already in the next gear. This is really annoying. Where should I begin looking at my bin file to address the slow decay in revs when I close the throttle?

By the way, I know the guy started my custom memcal with a 1987 350 automatic bin. I was worried that the auto bin was causing my driveability problems with the manual trans (slow rev decay when the throttle is released), but the guy said that it was easier for him to start with a 350 auto. bin for a hot 327 than start with a 305 manual trans bin. This is why I'm going to be burning my own chips now -- I don't want to keep dealing with someone else's guesswork and have my car running worse than it did when I had a Holley 600 doublepumper on it. (which ran flawlessly, I'm a glutton for punishment spending all this money to make the car much more complicated). Is it possible that the auto bin is what's causing the slow rev decay? Where should I look to address this issue in the bin?

 

You're suspicion is correct, you should not be using an auto bin. Get a 305 manual bin and adjust the cylinder size & injector size. You can always "cut & paste" the various VE tables from the 350 bin to the 305 bin.