I am finishing installation of a new cam in my 89 350 TPI. The marks I made on the injectors faded and I can't tell if number 6 injector is number 6 or 8. After reading the schematic it seems that the computer toggles all of the injectors on one bank and then the other. In other words 4 spray all at once on one side and then the other sides 4 spray. The schematic shows all of the green black striped (left side) through one fuse and splicing together at one point and terminating on one pin at the ECM. The pink black side (driver side) is wired similarly and lands on another pin. The ECM is then shown as having a toggling between banks transistor. Is this how the system works? I just want to make sure that the injectors are not cylinder specific. Thanks for your input in advance!
GW

 

Using the search function on this forum will let you know that the ECM has the injector drivers tied together internally, so all 8 injectors fire at the same time.

 

I went through this last year. If you look at your fuse panel, you will see inj bank 1 and inj bank 2 fuses. At least on my 91. Not sure on the computer grounds, I will have to look in on that tomorrow.

 

Each bank of injectors has a seperate power fuse.

They are fired thru a common ground in the ecm like he said.

later
Jeremy

 

Here's a wiring schematic for the injectors. Hope this helps.

 

All 8 fire at the same time. I have verified this by raising the fuel rails up with the injector nozzles in glass containers, and cranking the engine ( spark wire from coil to dizzy disconnected.)

 

Crazy question, I understand that all the injectors fire at once on our systems, that is refered to as batch fire, then you have sequential port on some of the other set ups, so that seems to be firing the correct injector at a set time in a progression. My question is on Batch Fire how come it dosent flood the engine because of the four stroke set up you have a cylinder fire every 90deg of crankshaft rotation, would you not saturate the cylinder runners with fuel before the valves open, especially with a large cam and the reversion that takes place with that. I know this works but was just currious how? I know this sort of takes place with carbs also but with a TPI set up you get the shot fired right in front of the head/runners where as the carb blends it in the plenum area and then it is drawn down the runner on the intake stroke.

 

maybe it fires once per completed firing order.

 

Answer is easy. :-)

Every time it fires, the intake valve is eithet open or closed :-)

Cut the fuel in half for every injection cycle and every cylinder gets hit with the valve closed once and than with the valve open.

Basically saying it takes two injector firings to fuel any given cylinder. So it works without flooding it.

There u go :-)

Also one of the reasons as emissions noose is tightened everything has gone to true sequential :-)

later
Jeremy

 

Boy do I feel silly about how I read the schematic in the first place. I too was wondering about the injectors spraying each time when valves are open or closed. Excellent responses cleared everything up and then some. thank you.
GW