[Diy_efi] Where to start...

Rich Rubel rrubel
Fri Mar 24 22:40:29 UTC 2006

I've been monitoring this list for a while, and asking one or two  
questions, but I'm now at the stage where I have to seriously start  
working on tuning my car.

What I have:

- 1986 Corvette TPI, very far from stock.  Bigger heads, 52mm TB,  
Lingenfelter cam and intake, headers, more.  Engine should easily  
make 400 HP, but doesn't feel like it (track numbers bear that out).
- PROMinator flash-programmable MEMCAL replacement on a 165 ECU, with  
8 slots for programs.
- WinALDL to monitor the car via the ALDL port
- TunerCat to make changes to the program
- a stock bin, an off-the-shelf MEMCAL bin (like a Hypertech), a  
first cut at a custom bin.
- laptop.
- GTech Pro (the good kind with full displays)

So far I've been limiting myself to changing simple things like fan  
temps, overdrive shift points (it's a 4+3 transmission), and things  
like that.

What I need to do is:

- bump the base idle because this cam wants 800 RPM minimum idle.  I  
know I can't just change the set screw on the throttle body.
- bump the base timing from 6* to 8-10*
- figure out why my idle surges with one bin and not with another,  
and why it's so rough
- make sure the A/F ratio is correct at idle, light throttle, and  
full throttle
- keep the car able to pass MD emissions treadmill test (which it did  
even in its sad state of tune)
- get the most power I can get at full throttle.

Since I can have several programs installed at once, I have no  
problem creating an economy program and a speed program... but even  
though I've read a bunch of articles on the net and looked at a  
couple books, I have no clear idea where to begin.  I haven't found a  
coherent explanation of the tables in the ECU and how changes in one  
place affect another, nor how the computer corrects for various  
conditions - so that it might override my changes if I set things too  
far off.

I realize this is a tall order, but any suggestions/help would be  
appreciated.  I don't have easy access to a dyno, but I do have the  
GTech for making comparison runs.



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