Taking the PFI plunge soon

[PJG1173]

Electrically, it look like the posted schematic is equivalent to the circuit I posted.

Impedance matching (resistor box) might not be everything that is needed. I'm doing more homework on the injector driver, http://automotivetestsolutions.com/u...waveforms.html

dave w

wow, lots of info on that page. may have to look at that tonight before I go to bed. also trying to track down an OScope and an operator for said scope. One of my friends says he has one of these but he's not sure how to use it as a scope, and its been 25 years since I touched one and it sure wasn't that small.

[dave w]

My O'scope is old ... see close up of an injector (inductor) discharging after injector turning off. Adding a resistor will effect how an injector discharges after the injector is turned off.

As a thought, this kind of "Homework" verges on "Product Development".

I recently received an order for several custom wire harnesses ... I'll be extremely busy the remainder of April. I'm going to have table any further "Homework" on this project until the harnesses ship, due date 30 April.

dave w

[brian617]

Dave, not being an electrical engineer help me understand the difference between your diagram and the one I posted assuming all the control side wires were connected to a single injector driver, rather than the four separate in the picture. I see your method puts the resistor between the control and the B+ and mine shows the resistors inline with the B+.

[dave w]

I see your method puts the resistor between the control and the B+ and mine shows the resistors inline with the B+.

That is correct. With resistors inline (series) the resistance of the resistors will add. With the resistor between the control and the B+ (parallel) the resistance is reduced. There are algebraic equations that determine how much the resistance is reduced in parallel.

Normally resistor boxes are used to increase the resistance to an injector. (resistors in series)

I'm thinking just the opposite, use a resistor box to decrease resistance to an injector. (resistors in parallel)

dave w

[PJG1173]

My O'scope is old ... see close up of an injector (inductor) discharging after injector turning off. Adding a resistor will effect how an injector discharges after the injector is turned off.

As a thought, this kind of "Homework" verges on "Product Development".

I recently received an order for several custom wire harnesses ... I'll be extremely busy the remainder of April. I'm going to have table any further "Homework" on this project until the harnesses ship, due date 30 April.

dave w

I see this is a little more in depth and complex than I thought it was originally going to be. since we are in race season there is no window for me to get this in until June. I started this thread for information gathering and decision making. after many hours of searching I have yet to dig up any threads of people going from TBI to CPI with out using the factory CPI unit, nor can I find where any one has done a marine intake conversion on a v6 using an odb1 computer. I would love to make the jump to odb2 and make this a lot easier but funds dictate I work with what I have. on another note I found my CPI MEMCAL BSWW which looks like it was superseded by BSWX only difference is idle speed. I believe its out of an Astro van so if there is any CPI specific to the MEMCAL I am covered there.

[whatif3387]

I've only read through part of this thread i'm not sure if this has been mentioned or not but I'm pretty sure an EBL from dynamicefi will do what your trying to do for rather cheap. Not as cheap as burning chips but for what you can do with the EBL I think it's definitely worth what it cost.

[PJG1173]

The EBL won't support my 4l60E, at least last I checked. If I swap out computers I will step up to ODB2 and go sequential PFI. the issue here is that I am looking to make the 8625/7427 fire 6 injectors like the old v6 central port injected (CPI) did with the same computer.

[1project2many]

the issue here is that I am looking to make the 8625/7427 fire 6 injectors like the old v6 central port injected (CPI) did with the same computer.

I realize this is probably obvious but electrically speaking the 8625/7427 never fired six central port injectors. The 8625/7427 triggered one injector which delivered fuel to six poppet nozzles simultaneously. The CPI injector was treated like a single TBI injector and was driven in peak and hold mode. Trying to operate six PFI injectors is somewhat different.

[dave w]

The EBL won't support my 4l60E, at least last I checked. If I swap out computers I will step up to ODB2 and go sequential PFI. the issue here is that I am looking to make the 8625/7427 fire 6 injectors like the old v6 central port injected (CPI) did with the same computer.

Use two computers, EBL for injection / '7427 for 4L60E. The '7427 will need power, ground, TPS, VSS, and DRP's to operate a 4L60E. Check with EBL, I'm sure they have a solution, maybe in your budget?

dave w

[whatif3387]

Use two computers, EBL for injection / '7427 for 4L60E. The '7427 will need power, ground, TPS, VSS, and DRP's to operate a 4L60E. Check with EBL, I'm sure they have a solution, maybe in your budget?

dave w

This is exactly what I'm running except with TBI. I'm running the EBL piggy backed with my original 7427 to control my 4l60e and it works great. Bob from dynamicefi was able to provide me with a very straight forward and easy to follow wiring guide for wiring up this setup. To wire both of them together took me about 30 mins to an hour it was alot easier then I thought and prior to this had zero experience with ecu wiring and tuning in general.

[PJG1173]

Use two computers, EBL for injection / '7427 for 4L60E. The '7427 will need power, ground, TPS, VSS, and DRP's to operate a 4L60E. Check with EBL, I'm sure they have a solution, maybe in your budget?

dave w

I have read about this before but, I prefer not to go that route. the 7427 can be made to run PFI on a V8 so there should be no reason it won't work on a v6 maybe not in the way I first envisioned.

[dave w]

I have read about this before but, I prefer not to go that route. the 7427 can be made to run PFI on a V8 so there should be no reason it won't work on a v6 maybe not in the way I first envisioned.

Maybe so? I should try an experiment using a MPFI V8 setup with 6 injectors when I setup the O'Scope.

There is the option of using a 1227730 (low cost ECM option that the factory used in many FWD V6 MPFI vehicles from 1989 ~ 1992) to operate the 6 injectors and have the '7427 operate the 4L60E. This might be the best option for time and money? Using the 1227730 eliminates the need for the EBL system. The 1227730 would work with a V6 distributor, instead of a coil pack typically seen with the FWD V6.

dave w

[brian617]

If you can make a V8 TBI .bin into a batch fire PFI .bin by doing the hard ware and software changes, stands to reason that you could do the same for a V6 TBI .bin right?

[PJG1173]

looking at the wire diagram for the 1227730 it looks like it is batch firing 2 sets of 3 injectors in parallel, so it shouldn't be any different with the 7427 should it?

[dave w]

There are different injector firing patterns for batch fire. I'm thinking once every 4th DRP for V8. I don't know if the V6 will work correctly if its injectors are fired once every 4th DRP. I'm thinking the V6 batch fire is once every 3rd DRP?

dave w