[Diy_efi] Hesitation

[Tomas J. Sokorai Sch.]

On Tuesday 27 June 2006 23:07, Scott Scott wrote:
> Thanks for the reply.  So the EFI system creates its
> own virtual accelerator pump of sorts? Makes sense, a
> little extra fuel to compensate for the higher demand.
>
>
> What do I do to diagnose this and correct it?

I'm running a GM TBI setup on my 302 too ('75 F100 pickup). 
What's your cam setup? it will rule your acceleration enrichment and spark 
advance choices.
I'm using a generic "RV" cam with 1.7:1 rockers and the acceleration 
enrichments grew *bigtime* regarding the original valvetrain.

Assuming you're using a 1227747 ECM, you'll need to play with values on the 
Delta TPS AE curve (starts at 0x314 in the bin) and the Delta MAP AE curve 
(0x30e) from your calibration BIN.

Regarding the ignition advance, you need to change the curve on your 
calibration BIN, and not just play with the base distributor advance.
My 302 likes big advance at idle. I'm running a total of 18 deg BTDC at idle.

BTW, if you haven't re-done of the whole VE and spark advance table tuning and 
you're just running the stock GM calibration, you should get these right 
first.

My calibration now runs *great*, but it bears very little resemblance to the 
original calibration. My truck would start and run on the original GM 
calibration, but very crappy compared to what I got with a lot of testing and 
tuning.

Regarding the case temperature, it depends on the environment temperature... 
If I drive after the truck's been in the sun for hours, it will be *hot*, but 
now in winter (I'm on the "wrong" hemisphere of the World :), the ECM case 
barely gets warm.
In fact, on short trips, the humidity and warm temperatures are getting *mold* 
to grow on the label of my ECM :D

-- 
Tomas J. Sokorai Sch.