Pulse/injector interrupt....

mrvette

Phantom of the Opera
Joined
Mar 24, 2008
Messages
15,207
Location
NE Florida
I understand that later engines have used a injector interrupt to stop firing them at higher/cruise speeds under light loads, to save fuel.....

SO, being as I have a batch fire system, the old speed density type, and finally have a smooth running engine, I am wondering about the following....

the present wiring is firing the injectors in two banks, drivers/passengers....

I know that the old Caddy Seville sytem fired two banks also...but they did it differently....7218, then 4365.....

when messing around looking for the damn rough idle years ago, I had rewired the thing like the seville pattern....engine ran the same, no surprises there....

I also had a common wire come loose that disabled the driver's bank of injectors, engine ran like shit at idle, but not all THAT noticeable at cruise, power was piss poor under acceleration, obviously....but engine returned to normal operation when I found the wire, easy fix just listen to the injectors, woopie doo....

SO, the question is, what if I permanently rewired the vette to the 4 corners, then 4 middle cylinder firing pattern, I already know it will run the same, so then to introduce a interrupt signal to the computer, from my own electronics riding piggyback on it....

kill one bank, then kill the next bank, and alternate back and forth until intake mani indicates high power is demanded, my own version of the modern tech....

WHAT WILL THIS DO to the long range durability of the bottom end of this '89 factory 4 bolt truck block??


:crutches::bonkers:
 
Two things: I'm not following your choice of what cylinders to cut. Unless I'm misunderstanding you, there's going to be some very odd spacings of the power strokes. Second, make sure the O2 sensor isn't sitting downstream of any of the disabled cylinders, sensing all that uncombusted air.
 
I tried to digest what you are thinking of here and gave myself a headache.:D

First off, tell us more about the "introduce a interrupt signal to the computer, from my own electronics riding piggyback on it...." How are you thinking of doing this on an old GM ECU.

Running in closed loop, won't the O2 sensor tell the ECU that your running lean, after which the ECU will start trying to correct with longer injector pulses. Sounds to me like you may be chasing your tail without major reprograming of the ECU
 
Two things: I'm not following your choice of what cylinders to cut. Unless I'm misunderstanding you, there's going to be some very odd spacings of the power strokes. Second, make sure the O2 sensor isn't sitting downstream of any of the disabled cylinders, sensing all that uncombusted air.

Mike, not sure of the total concept, just cut some cylinders for fuel delivery like a more modern computer, and so I heard they did it once every other power stroke, but that applies for every cylinder....so why not just cut one whole batch of the existing system, for every other stroke.....

so to make a electronic interrupt controlled by the MAP signal, and idle signal to enable a driveability range ....I found my old kludge up on the shelf from years ago, and so played with it this afternoon, and found that the 72184365 setup was operationally the same as the OEM TPI was...

but to get more economy at speed, how to cut the cylinder feed like a modern engine.....without getting aftermarket expensive....

I can fab up a device to do that, but wonder more about how the mechanicals than the electronics....and yes, the O2 sensor will read way lean, so to introduce a .5 volt false signal into the computer feedback loop when needed...

hate spending bux on a aftermarket overpriced hard to program system...much less any communication problems with that system....so am thinking of my own deal, much like the mechanical changes that have served me well, so far....
 
Last edited:
I don't think you wouls see much of an increase in efficiency unless you held the valve open so that you eliminated the compression stroke.
 
Are we talking the old, failed Caddy 8-6-4?

I don't think you wouls see much of an increase in efficiency unless you held the valve open so that you eliminated the compression stroke.

NO, nothing mechanical,, so to kill just the driver's bank, leaving the O2 sensor in the pass side seeing normal operation....like when that wire worked loose....

I"m a little worried about crankshaft harmonics, hence this question...
 
GM's current Active Fuel Management technology uses a solenoid to deactivate the lifters on selected cylinders of a pushrod V-layout engine.

http://en.wikipedia.org/wiki/Active_Fuel_Management

Ok so a quick glance says maybe 8% economy increase....hardly worth the effort to replace an engine over....

wonder about the fuel interrupt on injector firing....

that is a simple electronic thing, even if replacing the computer, certainly cheaper to this old geek...

:surrender:
 
Top