Re: Rookie questions
I can answer a couple of them:
gta324 said:
2. Do I have to rewire the ECM to get it into Quasi-mode?
If you're talking about quasi-async fueling, then No, you don't have to mod the ECM. There is a parameter (don't remember which one, off the top of my head) that adjusts the switch between quasi-async and sync fueling - you just raise the RPM higher than your expected max RPM.
gta324 said:
4. What exacly is quasi mode?
Sync fueling gives a squirt of fuel from the injectors with each revolution of the crank. Quasi-async gives a squirt of fuel every
other revolution -- so you get twice as much fuel per squirt, but half as many squirts. The reason this is an advantage is that large injectors are very hard to control at very small pulse widths. Halving the rate at which the injectors are pulsed allows you to double the pulse width (to get the same amount of fuel), improving control of the injectors.
gta324 said:
5. Is there any more forums about tuning the -749 ECM?
No specific forum(s) of which I'm aware. However, there's a lot good info at the GM-ECM page on DIY-EFI.org (
http://www.diy-efi.org/gmecm ). They also have a mailing list to which you can subscribe.
You should also get a copy of the GM P4 document, which explains a lot of what the different parameters/tables do (it's good, but not complete). You should be able to find it on GM-ECM.
Finally, look on ChiTownSyTy (
http://www.chitownsyty.com ) for BG's tuning/burning info (click on the "Tech" link at the top). There's a lot of good, practical info there.
