Help Get me Started

[edfiero1]

Hi Guys - Another Newb here.
I want to try to learn to tune. I've got a couple of books, but haven't found one to really get me started.

I have a 1227747 ECU, that I plan to use drive a 4.3 L Throttle body Injector on top of a 2.7 L , 4 cylinder.

I know I obviously have to adjust the Number of Cylinders parameters, but what other adjustments should I be looking at before I even attempt to turn the key? For example, are the VE tables, fine to start with the stock values, or do I have to lower them by a factor of 2.7/4.3, based on the lower displacement of my engine? I don't see a parameter jumping out at me of where to set the displacement.

Thanks

[joegreen]

They made a throttle body for a 2.8l engine. It might be better to use that instead of the 4.3. Of course it depends on how much hp you are making. Some other more knowledgeable people will chime in.

[edfiero1]

Bump. No one with any suggestions on where to start when taking a 6 cylinder stock tune and reworking it to run a 4 cylinder with a big cam??

[sturgillbd]

You didn't specifically state what engine you are converting to GM TBI. You will have to get some signals such as distributor reference pulses to the ecm. If the engine has a hall effect type distributor, you may be able trigger a GM ICM with it.
This may help you on fueling. http://www.gearhead-efi.com/Fuel-Injection/showthread.php?88-Tuning-BPW-%28BPC%29-on-7747
You will need to know the flow rate of the injectors in the throttle body you have. http://www.gearhead-efi.com/Fuel-Injection/showthread.php?81-GM-TBI-Injector-size-color-and-part-numbers

The following text is from from the TunerPro XDF file from the $42 mask which is used on the 1227747:

If other than stock engine, injectors and fuel pressure use the Injector Sizing Spread Sheet to calculate BPW!
http://www.gearhead-efi.com/Fuel-Injection/showthread.php?170-Injector-size-vs-HP-pressure-math-needed&p=2589&viewfull=1#post2589


TBI:
Val = 1461.5 * (VOL/RATE)
VOL = Vol of 1 Cylinder in liters, (0.7125l)
RATE = Injector flow in gms/sec
5.7l = 7.71 gms/sec (61.2#/HR)
(VOL/RATE) = 0.0924 l/gm/sec

Cylinder volume and injector flow rate are combined in this calibration value. A typical value for a 5.7 liter V8 is 135.

Cylinder volume is 5.7/8 or 0.7125L

Injector flow rate is 7.48 grams/sec, (61.22#/hr/injector)

Using the formula BPW = 1461.5 x (cyl vol / inj flow rate )

= 1461.5 x (0.7125/ 7.71 )

= 135

Two more threads with relevant info:
http://www.gearhead-efi.com/Fuel-Injection/showthread.php?97-DIY-Fuel-Injection-for-any-Carbed-Engine!-HOW-TO!
http://www.gearhead-efi.com/Fuel-Injection/showthread.php?21-Building-a-GM-EFI-Small-Cap-Distributor-for-TBI-Conversions!

[edfiero1]

Thanks Srurgillbd.

I thought my question was generic enough that more detail wasn't needed, but I can certainly provide more info.
The engine is a Pontiac Super Duty 4 cylinder. Same as the Pontiac Iron Duke, except Bored and Stroked to over 2.7 liters and with a big Cam and intake. I have a stock Iron Duke Distributor complete with ICM.
I am starting with the stock tune from a 4.3 V6 manual trans. My TBI is from the same 4.3 engine, so I should be good on the flow rate.