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Questions about fuel injection

2K views 14 replies 4 participants last post by  HahnsB2 
#1 ·
I am getting ready to fuel inject my Bronco. I have been looking at Holley, Accel DFI, and Fast XFI 2.0.

Accel DFI generation 7 only reads narrow band o2. It uses a data logger box to convert wide band o2 into narrow band so the computer can read it. Fast XFI 2.0 reads wide band o2 directly. A technical represenative from Holley told me that the Holley system reads wide band o2 directly. Of course there are four systems from Holley that come to mind. The older; Projection, and Commander, and the newer; Avenger, and HP. Oh and I almost for got about Big stuff 3. That one seems good too.

A technical represenative from Accel who is also the sales person told me that a highly tuned TBI with Accel DFI generation 7 on wide band o2, and properly sized fuel injectors would run as good as multi port fuel injection. He said that Sequencial mpfi has a smoother idle and cleaner emissions than batch fire mpfi but emissions are hardly relevant for me.

This is not junkyard fuel injection. This is buying a good aftermarket computer, injectors and new harness, and new sensors.
 
#2 ·
Why not just go with oem fuel injection? Those systems are high priced as hell for what they do.

I run Mustang EEC-IV EFI myself, tuned with Moates Quarter Horse. 4 tunes off a rotary switch. I deleted my EGR but I use the EGR wiring to monitor and data log a single wideband sensor. The PCM still uses narrowband for control and does great.
 
#3 ·
How much harder is it to tune EEC IV than one of these aftermarket system? I will still need new fuel injectors as 19 lb/hr is too small. I think I can get a new EEC IV computer for $100. I am buying fuel injectors anyway. The wiring harness is pretty much a standard price. So I am saving money on the computer by buying a Ford EEC IV instead of a $1,000 aftermarket computer. I recently visited the website for Quarter Horse, and I think it cost $250.

I am going to go do some more re search on EEC IV. I definately want to run a wide band o2 sensor. I don't want 14.7:1 air fuel ratio because I do not have any catalytic converters on this vehicle. 14.7:1 keeps the catalytic converters alive, not pertinent here. I want a 12.5-13.5:1 most of the time, and as high as 16.5:1 at light load cruise. I think my truck that I drive runs at 14.7:1 until high load/full throttle when It goes int open loop.
 
#4 ·
There is a bit of a learning curve to it. But parts selection makes it a little easier. I run 24lb injectors with a Maf calibrated for 24 lb injectors. So I haven't changed much more than Timing tables and flags. By flags I mean disabled various DTC's and EGR, TAB, and Tad. I also run an automatic PCM (A9P) in a manual so that flag has been changed as well. I also do not run a distributor, I changed a flag in the A9P to allow it to run EDIS-8. I find crank trigger firing coil packs way more accurate. Kinda cool finding out what kind of options some of the PCM's have once you turn them on. IE: shift light, cooling fan control, EDIS etc.

There are forums for QH with some pretty knowledgeable people so that helps a bunch. Stick with a common PCM (A9l, A9P) and the support is great.

You can set desired A/F ratio no problem. You just can't use a wideband to control it unless you run some sort of pricey converter or use a newer PCM that will support them. As I stated mine is controlled off of narrowband O2's. However I have a single wideband plugged into my unused EGR harness. I use it for data logging and helps a bunch with getting a tune dialed in. Way cheaper than buying expensive wideband controllers.
 
#8 · (Edited)
I've been looking into MS as well for when I finish my boosted project. Seems alot more complicated but cheap, and a little more boost friendly.

I'm a little torn though, already having a QH, I can use it tune to where I want it and then just burn a simple chip when I'm done. $80 versus buying a new system.
 
#9 ·
I did a bit of reading on Moats Quarter Horse today. There is a great deal of technical literature on it. Mega squirt may cost less but I do not have the electronics skill to build one of them. I agree that Mega squirt 3 with all the bells and whistles is the way to go but I don't have the skill or know how to build it.

Here's the honest truth; I can select and buy computer hardware off the shelf, and put together a PC and turn it on. I can get a Holley 4 barrel, lookup what jets, accelerator pump-shot to put in, and start the engine running a bit rich. I have soldered wires back into circuit boards but I wouldn't say I am very good at it. I have cleaned the test port on an EEC IV computer before. I can confidently say that I can solder two wires together.

I am much more comfortable just getting a Ford computer, getting Moats Quarter Horse, and following instructions.

So for my update, I am reading everything I can about modifying and tuning Ford EEC IV. I figured out that the data logging software is recording the voltage input from the wideband o2 to the ecu and that recorded voltage is to be corresponded by its lambada or air fuel ratio voltage in reapect to 14.7:1.

Thanks for the help. I am slowly catching on.
 
#10 ·
You might ask over on their forums about some of the newer PCM's before you buy one as well. My thinking is maybe a PCM out of like a MKVIII or something might use 2 widebands already. Would probably be cheaper than the desireable mustang ones. Granted you'll probably have to re-pin the harness at the PCM for it, but that's pretty easy as long as you have a diagram. The biggest question is if there is support out there for a strategy that meets your needs.
 
#11 ·
I run Holley Pro-jection on my Bronco.
Once it is calibrated and running the closed loop it is a great set up.

I run 12.8:1 under load and 15.1 under light/no load.

Compared to a carb it is a dream! It is also simple to set up, a little time consuming but easy to do.

It is a TBI with 2 80# injectors and I have had no issues with the system.

BTW I picked it up used for $300 complete!
 
#12 ·
Does 12.5-13:1 really make the greatest torque or is that only under heavy load to cool the combustion chamber? Under light load will 12.5:1 make more torque than 14:1?

On my engine, the one that is getting this fuel injection, I could rev 6,000 rpm on a 350 Holley 2v in park, but in drive, under load I could only turn 5,000 rpm. I don't know if that is pertinent.
 
#13 ·
I personally run 14.7-15AFR under cruise down to 8in/hg vacuum, then it drops to 14 and goes down to 13 at zero vacuum, then drops to mid 12s all the way down to 11.5 under boost.

IMO under light load there is no reason to be any richer than stoich.
 
#14 ·
Ok, so you say that under light load 12.5:1 makes no more torque than 14:1 or 15:1? I make the torque as lean as the engine runs good? If my engine runs good at 14:1 or 15:1 then I am not going to get more torque at 12.5 or 13.5:1?


If "it runs good then it makes all the torque" than I can go with that premise.
 
#15 ·
I'm not saying there isn't a torque difference, but you'd probably have to throw it on a dyno to notice any difference at light loads. Heavy load is when you typically want torque so it makes more sense to have that area richer than light loads IMO.
 
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