Min. injector off time

Scott Shotton stucky at interaccess.com
Thu Feb 5 04:44:59 GMT 1998


Mikey B Sorensen wrote:
> 
> Hi,
> I'm new to EFI and have a few questions:
> 1.  Explain the difference between : Staged Injection, Sequential,
> Multipoint, Batch fire, TBI... (I know a few of them..I think.)

TBI= Throttle body injection.  1 or more injectors over the throttle
plates.

PFI, MPFI, MFI, TPI, SEFI=  An injecyor for each cylinder.  Usually
banked (ie V8... 2 sets of 4 injectors pulsed alternately).  Sequential
(becoming more and more common) uses aditional input to fire each
injector just before the appropriate intake valve opens.
> 
> 2. If I were to make my own ECU + Injector drivers.. would the Peak and
> Hold be the way to go??.. since I from what I understand can control both
> kinds of injectors.. (Saturated or Peak and Hold..).
> 
> 3. I had a 87 Vette with the 350 TPI and it had a cold start injector..,
> was that to get better idle? and is it only used during cold starts or
> also during peak load/rpm??.

The newer TPI's don't use cold start injectors because coolant
temperature tells the ECM it is cold and the ECM increases injector
pulse width.  Same effect.

> 
> 4. Haltech and other uses a MAP sensor.. is it better that a Mass Air
> Flow like the 350 TPI or the "flap" type air measurer??, What is the
> advantages/Disadvantages between the 3 types??

The plastic MAFs that GM used to use had a vibration sensitve problem. 
You could give them a pop with a screwdriver, and the car would stumble
or die (if the sensor was bad).  I prefer MAP (or speed density).  MAFs
also have a hot wire that can be damaged by someone messing with the
sensor when they are not supposed to.  Vain Air Flow Sensors... usually
non-domestic applications, don't have a lot of info on these, my
opinion.. probably leave well enough alone.

> 
> I am currently going for my EE degree, so it's o.k to get technical...
> :-).
> Thanks in advance and I think this is a great list, with good
> question/answer, unlike other lists...
> 
> Michael.
> 
> _____________________________________________________________________
> You don't need to buy Internet access to use free Internet e-mail.
> Get completely free e-mail from Juno at http://www.juno.com
> Or call Juno at (800) 654-JUNO [654-5866]



More information about the Diy_efi mailing list