Converting 767 to EFI with stock manifold

[Spittybug]

I did a lot of searching around for fuel injectors today, and came up with nothing. Well, I could find 19 lb/hr (or 200cc/min; same difference) injectors, but I couldn't find anything about how tall they are. I did find one place that sold 76mm tall injectors, but they were 32.5 lb/hr, which isn't going to work here. I'm considering just going to the nearby NAPA and asking for their tallest 19 lb/hour injectors and seeing where that gets me.

Also: any preference between high or low impedance injectors?

Thanks again

-- Joe

HIGH. Low seems to give nothing but problems as far as I can tell. And you need extra circuitry (fly back). The 19# injectors are sized right. Any bigger and your pulsewidth at idle will be too short and you'll have terrible trouble getting good fueling at idle. Try googling fuel injectors and look at the picture results. See if you can then narrow down which are the tall ones.

[opethmike]

HIGH. Low seems to give nothing but problems as far as I can tell. And you need extra circuitry (fly back). The 19# injectors are sized right. Any bigger and your pulsewidth at idle will be too short and you'll have terrible trouble getting good fueling at idle. Try googling fuel injectors and look at the picture results. See if you can then narrow down which are the tall ones.

This this this over and over again. I had SOOOOOO many problems trying to use the low impedance injectors that came with my Renault manifold. The very moment I switched to high impedance and set the parameters per the documentation, VROOM!

I love that MS3 allows VE tuning by as narrow as 0.1%. You'll be able to get insanely accurate AFRs with that. I would love to get that accurate, but seeing as I don't use a TPS, or even an IAC, MS3 would be rather overkill for me

[jangell]

Thanks guys -- I'll be sure to get high impedance injectors.

GIS was a good idea -- it led me to the tall EV1 and EV6 bodies. 19 lb/hr EV1 units are commonly used in Mustangs, it seems, and are around 74mm tall; the EV6 injectors don't seem to come in 19 lb/hr, instead starting at 24 lb/hr. The only obvious down side is that it seems that many places sell them in sets of 8.

I found some diagrams showing the injector dimensions. Assuming I'm reading them correctly, I think they're the right size for the injector ports in Owen's rails and the DMC's cylinder heads -- the rails have ~13mm holes in them, and the diagrams show the O-rings as ~13.5mm.

Injector-Body-Style-Comparison.jpgInjector-EV1-Dimensions.jpgInjector-EV6-Dimensions.jpg

I thought I'd sanity-check here before I order any. I only really found four brands in my searches:

• 8 Pack of Accel 19lb EV1 injectors for $291. They sell them individually for $50 each -- an 8 pack is cheaper than buying six separately. Accel turns up the most when searching for "19lb EV1" on Google.
• Delphi 19lb EV1 injectors for $40 each ($260 for 6).
• 8 Pack of Venom Performance 19lb EV1 injectors for $209. The specs list them as having only a 2" (~50 mm) overall height, while the diagrams above suggest they should be ~3".
• 8 Pack of TREPerformance 19lb EV1 injectors for $200 on eBay

My attempts to find the Bosch variant (which appears to be 0280155735) finds only remanufactured ones on eBay, with other sites listing them as discontinued.

Thanks!

-- Joe

[AdmiralSenn]

I gather you're doing MS-controlled spark if you're using the VR, right? How obvious was it that the problem you were having was noise? Did you need to do a lot of trial and error, or were you seeing an obviously bad signal in MS?

Not yet, I made the switch because of the noise problem. It was fairly obvious, the needle on the tuning software would swing wildly and the logs showed complete random noise. Others have had less spectacular noise problems but mine was an easy diag
I noticed the MS docs suggest using an isolator from Radio Shack if noise problems become enough of an issue. I'm not totally sure what an "isolator" is defined as (just a big capacitor?) or where exactly you'd put it (if it's a big capacitor, then presumably not on the tach line, since I assume it would smooth out or mask the tach pulses themselves).

Probably not strictly necessary.


I was looking at this specific one for both because the DIYAutotune description suggested it would work for both CLT and IAT. I have no idea how the closed vs birdcage sensor designs might behave differently, or if they're functionally identical for these purposes.

You're probably fine with the closed element. I wanted the faster response because of where I intend to take my project in the future, and it was only a few dollars more.


-- Joe

Hope that helps. Looks like you're on the right track with the injectors. I can confirm that bigger is not always better. It is theoretically possible to run huge injectors but unless you're planning on adding turbos or something it's not necessary and makes tuning (especially at idle) really difficult. And that was with the high impedance, my previous attempt with 22lb low-impedance injectors actually idled worse.

MSIII is cool, but wasn't available when I built my unit. If you go that route I'll be curious to see what you experience as it's something I've considered for the future.

[jangell]

Not yet, I made the switch because of the noise problem. It was fairly obvious, the needle on the tuning software would swing wildly and the logs showed complete random noise. Others have had less spectacular noise problems but mine was an easy diag

Good to know. I was curious about using the VR without using MS for spark, since I wasn't sure if tapping it would interfere with the stock ECU. I'll try the coil first, and then I'll bug you about your VR setup if I can't get that working reliably.

You're probably fine with the closed element. I wanted the faster response because of where I intend to take my project in the future, and it was only a few dollars more.

OK. I'm probably not going to add much else on to boost my engine; I have an automatic, so the combination of aggressive cams, free-flowing exhaust and MS are probably getting me close to the theoretical 200 HP limit at the flywheel that the transmission can support (although I imagine my true HP is quite a bit lower than that, and I haven't put it on a dyno or anything).

Hope that helps. Looks like you're on the right track with the injectors. I can confirm that bigger is not always better. It is theoretically possible to run huge injectors but unless you're planning on adding turbos or something it's not necessary and makes tuning (especially at idle) really difficult. And that was with the high impedance, my previous attempt with 22lb low-impedance injectors actually idled worse.

I'll stick with the 19 lb/hr injectors then. Thanks!

[QUOTE\MSIII is cool, but wasn't available when I built my unit. If you go that route I'll be curious to see what you experience as it's something I've considered for the future.[/QUOTE]

I'm probably going to get the III. I don't expect it'll be much different from using the II, but I guess we'll find out.

Thanks again

-- Joe

[AdmiralSenn]

Good to know. I was curious about using the VR without using MS for spark, since I wasn't sure if tapping it would interfere with the stock ECU. I'll try the coil first, and then I'll bug you about your VR setup if I can't get that working reliably.


-- Joe

Whoops, I forgot to clarify. Yes, I am using the VR input without controlling spark. Since I still need the ignition ECU for the time being I just tapped the leads into the existing harness and piggybacked off the signal. No worries, less wire to run and hides nicely behind the ECU mounting tray.

You can actually tap coil negative in the same place, since it comes from the same connector on the ignition ECU. Running a wire to the coil basically gives you a huge antenna to pick up more noise. Even with shielded RPM-signal-specific wire and a shielded coil wire it was an issue on my car.

Either way works, but I really think the VR method is the way to go since you have built in adjustment pots on the MS board. These cars are very electrically noisy for a number of reasons, anything you can do to calm it down is a plus.

[jangell]

Ah, cool -- I'll have to ask you about how to do that once I start putting things together.

I finished up my fuse box replacement today, and took the mixture unit out of the car. I also tried to take out the intake manifold; when my more knowledgable friend helped me put the engine together last time he used some kind of gasket sealant stuff on the mating surfaces, and I can't get the intake manifold off (all four bolts are out and the cold start pipe is off). Next weekend I'll take out the injectors so that I can try to get a pry bar in there, and maybe hammer on a block of wood against the end of the manifold to try to break it free.

BTW, what does everyone do about the now-unused wires and connectors on the harness, like the CPR and CSV? Just clip them off? Or do you make a new harness rather than ruin a stock one?

-- Joe

[Spittybug]

I found that I removed so many wires that it made sense just to make a new harness. That really cleaned up the engine bay too. I used the polyester loom material you can buy at places like Frys (for inside computer cases) and heat shrink tubing to seal the ends. Route things where YOU want, not where some engineer wanted it to save a few inches of cost....

[jangell]

Works for me. Where the bulkhead connectors difficult to find? I expect everything else is ring or blade connectors.

Thanks

-- Joe

[Spittybug]

For the few you need to keep, I just used female bullets. I had to spread them open a little and then I used shrink tubing down to that size so that they stay on tight.