TBI, V8, 4 injectors,...how to configure batch injection?

[wampa]

Hello all,
I'm currently building my wiring harness for my MS3pro EVO, to run my small block 347cid V8 in my 67 Mustang. I'm having a heck of a time figuring out how to configure my fuel injectors - figured you smart people may be able to guide me. I have spent hours reading manuals and old posts, and I cannot find a definitive instruction on this

What I have:
I have a crank sensor (36-2 wheel)
I have a cam sensor (modified my distributor to give a signal once per engine cycle)
I am setting up coil-near-plug sequential ignition
I have 4 injectors that came as part of my Holley EFI "4-barrel" TBI unit.
Firing order is 1-3-7-2-6-5-4-8

What my injection goal is:
I want to fire injectors 1&2 (the "front" two TB injectors) simultaneously, and then 3&4 (the rear two) simultaneously 180 crank degrees later. Then 1&2 again 180 deg later, and so on. So, a pair of injectors fires simultaneously every 180 crank degrees.

Specific Question:
How do I configure this in tunerstudio? Sequential: OFF, Squirts per Engine Cycle: 4, Injector Staging: Alternating, No. Cylinders: 8, Number of Injectors: 4 ???
How do I physically wire the 4 injectors, given the 8 (A-H) driver channels???

Thanks so much for any advice

[wampa]

Well, I think I've figured this out. I'll answer my own post just for the record. I'm going with these setting and wiring:

Tunerstudio settings: Sequential: OFF, Squirts per Engine Cycle: 4, Injector Staging: Alternating, No. Cylinders: 8, Number of Injectors: 4
Apparently by selecting "Number of injectors: 4" only injector channels A,B,C & D are activated (E-H are not). Based on my setting above, channels A+C will fire simultaneously, then 180 crank deg later B+D will fire simultaneously , then 180 deg later A+C fire gain, and then B+D again. So that's 4 total injection events over one engine cycle (720 deg).

The biggest link I was missing is that with "Sequential: OFF", the injector channels fire A+C together, then B+D together. It totally makes sense...I just can't find anywhere in the MS3 manuals that actually spells this out - I had to call tech support in the end. So I'm guessing that what everyone refers to as Bank1 is equivalent to injector channels A,C,E,G and Bank2 is B,D,F,H ?

I will wire one pair of injectors to channels A and C, and the other pair to channels B and D.

[Six_Shooter]

Yes, that should alternate between pairs, but why are you worried about it, firing them all at the same time is a viable way to fire the injectors in a TBI setup.

[wampa]

I'm referring to my fuel injectors, not the coils. The Holley TBI unit I have, when controlled by the Holley Terminator EFI ecu, alternates pairs of injectors like this - I'm trying to mimic this injector strategy.

[Six_Shooter]

I know you're taking about your injectors... You wouldn't fire coils in a "batch" strategy...

Using alternating, batch or sequential are all viable ways to fire the injectors and you will likely notice very little Difference, if you notice anything at all, especially when using TBI.

The throttle plates are all 1:1 right? The only time you'd need to do can something didn't with injector firing strategy is if your linkage was progressive, then you'd notice the problems there, bit alternating wouldn't be the answer, secondary fuel injectors would be.

[wampa]

Thanks Six_Shooter, I figured you knew I was talking about my injectors - just checking cause you had typed "coils" earlier. Thanks for the clarification though!

I'm going to try this alternating setup first since it is the method recommended by Holley, although I'm open to experimenting with other strategies once I get it running.

About the throttle plates - interestingly, they are not totally 1:1. The TBI unit has four "barrels" and four throttle plates, but a primary throttle shaft turns the front two throttle plates and a secondary shaft turns the rear two throttle plates - just like a carb. The foot throttle cable will directly actuate the primary shaft, but the secondary shaft progression is driven by linkage coming from the primary shaft. The primary throttle plates are always slightly open even at idle, as their resting position (call it 0% TPS) allows for the bulk of air flow for low idle (there's also some marginal air flow from the IAC stepper, just to smooth the idle). At 0% TPS, however the secondary plates are fully closed! When applying foot throttle and the primaries begin to open more, the secondaries begin to move around ~3% and then all throttle plates reach 100% open simulaneously.

I spoke to Holley and pointed out that there would be little/no airflow through the secondary plates at low idle, and so I thought it was weird that they advise to always fire the rear pair of injectors. They insist that the optimal and intended strategy is to fire the injectors alternating between front pair and rear pair. The injectors are BELOW the plates, and the IAC does flow a bit of air near the secondaries, but I still was surprised that their injector strategy wasn't "staged", where the secondaries turned on at some TPS% above zero.

I'll try what Holley says first, and adjust as necessary I guess. This is my TB by the way:
http://www.holley.com/products/fuel_sys ... ts/534-216

[Six_Shooter]

So I did put in coils for some reason, edited to be correct...

Unless you're using a Holley ECU, and since you're posting here, I get the feeling you're not. lol Forget what Holley says. Do your own testing and use what ever strategy seems to work best for you. I can't imagine any reason why alternating would work any better than batch in this case, the only possibility would be if the injectors are VERY large on a small displacement and the ECU is limited in low pulse width control, which has not been an issue with Megasquirt in my experience.

With the fuel being injected under the throttle plates, then the throttle plates being 1:1 or progressive really doesn't matter. I'm used to fuel being injected above the throttle plates in a TBI setup and that's why I mentioned what I did. From what you describe that would still be considered 1:1. The progressive linkage would open the rear throttle plates considerably later than than the front ones would open, generally somewhere around 30% throttle, the secondaries would start to open and then open very quickly.

[alteredz]

wampa, I JUST received a "scratch and dent" 534-216 throttle body from Holley. They had a couple of these on amazon.

I was wondering how your install worked out and if you went with the Holley recommended 180 stagger or not. I read the same sheet you did that said that's how they want the injectors driven.

<intro><offTopic>
I'm on the fence trying to decide what to do for an ECU now - Holley HP is plug and play and would probably work great. Haltech is full of features. None of the many other ECUs really interest me.
But I'm an old Megasquirter - over 10 years ago, I had a MS 1.5 with daughtercard running on a 327 SBC years ago with an old Pro-jection 700cfm TBI. Worked fine until a week before an HPDE and an channel gave out, so I threw a carb on it. I've wanted the car to have EFI for a while but just went to an 830HP with weber plates - to get enough air in the engine (700cfm TBI wouldn't be enough for a 500hp 406)
Thankfully this new TBI has high-z injectors and should be more forgiving on an MS3.

I'm leaning heavily towards an MS3 EVO or I might build my own MS3 with extras.

Ultimately I want to convert an old Hilborn injector manifold I have to EFI, so a feature-laden ECU for making that drive nice is important. MS has blended mapping, so I like that.

Six_Shooter, if you are reading, the engine I'm working on is a 406c.i. SBC in a 240Z ;)
</offTopic></intro>

[wampa]

alteredz, sorry for the SUPER late reply...the setup works quite well so far. What setup did you end up with? Do you have it running?

[alteredz]

alteredz, sorry for the SUPER late reply...the setup works quite well so far. What setup did you end up with? Do you have it running?

LoL, but you DID reply! Thanks! I am headed towards building an MS3 with the extras. Still haven't moved on doing anything yet. I will probably start building the MS3 soon.
I did just yesterday pick up a used Victor Jr. manifold and a Weiand 7546 single plane - $125 for the pair.
I've been reading and watching videos about how these TB systems don't work so well on dual plane manifolds. I have a RPM Air Gap copy on the engine now and will probably start with the Victor Jr - the TB is shorter than the carb, so hood clearance should be good.

[wampa]

alteredz, sorry for the SUPER late reply...the setup works quite well so far. What setup did you end up with? Do you have it running?

LoL, but you DID reply! Thanks! I am headed towards building an MS3 with the extras. Still haven't moved on doing anything yet. I will probably start building the MS3 soon.
I did just yesterday pick up a used Victor Jr. manifold and a Weiand 7546 single plane - $125 for the pair.
I've been reading and watching videos about how these TB systems don't work so well on dual plane manifolds. I have a RPM Air Gap copy on the engine now and will probably start with the Victor Jr - the TB is shorter than the carb, so hood clearance should be good.

I am running a dual plane manifold and it seems to work well. I haven't monitored fuel distribution (via individual cylinder lambda and/or EGT measurements) but the engine idles smoothly, responds well, and makes good power. That said, I suspect the key to success is to ensure that the two intake manifold banks are not totally sealed off from each other. The "wall" that separates the two intake planes should be machined down slightly, as is done on most Edelbrock RPM Air Gap manifolds, allowing some communication between planes. This ensures that the MAP sensor is exposed to BOTH intake planes of the manifold and is thus capable of giving a steadier and more accurate pressure measurement. Without the wall cutout this Holley Terminator TB MAP sensor would end up being sealed off from the upper plane and would only read the lower plane of the intake - I suspect this is why people have problems.

I have the wall cutout, but I additionally installed a 0.75" phenolic spacer between my Air Gap manifold and the Holley TB. The spacer is wide open inside (not just individual "barrel" holes) so I my MAP sensor is able to measure in this common air space, before the air flow is divided into the two planes.

I also considered some of those sincle planes, but was afraid I'd sacrifice low end torque for high rpm gains. Hope this helps - I need to turn on email notifications so that I know when people respond to my posts..sorry!

[swedishknievel]

Wampa,

I am looking to do something very similar to what you have done: '65 Mustang Fastback, 331 stroker, AFR heads, flat tappet hydr. cam, RPM Air Gap manifold, manual trans.

Looking to ditch my Holley 770 carb and MSD-6 digital / MSD Billet dist in exchange for a Holley Terminator TBI setup. Holley is not being very forthright with details about their ECU. They really want to sell me their distributor for ignition timing. I would rather go with the LS2 truck coils.

What was your experience connecting and calibrating the Holley TBI unit to the Megasquirt?

I have one Microsquirt project under my belt (Volvo B230FT) and am very comfortable building harnesses and figuring stuff out (the Volvo crank sensor generated too much voltage for the microsquirt - had to install a shunt resistor; needed a true TPS, not a switch, adapted one off an Acura etc.)

I have a Ford OEM cam "synchronizer" from a late '90s vintage V8 that I believe will generate one pulse for each full cam revolution. I am thinking I can get away without a crank trigger if I have Cam trigger, right since the crank signal is the cam signal /2.

Are you firing your coils sequentially or batch? Did you run your injectors both ways (2 at a time and 4 at a time)? What else can you tell me before I get started? Would you be willing to share your msq file?

Thanks.

[wampa]

swedishknievel,
Sorry for the late reply - I hope this gets to you.
I also wanted to stay away from the Holley ECU and other stuff in the package - in other words I ONLY used the throttle body assembly, and wanted the versatility of MS/Tunerstudio to run everything. The Holley TB interfaces very well with my MS3 ECU. I had to characterize every device on the TB (IAC, MAP, MAT, TPS, injectors) so I knew what I was working with and how to wire them correctly. If you move forward with this setup, I would gladly help you through that stage.

I also tried the ford cam "synchronizer", but didn't get it to work. I got an Explorer part, and it did not physically fit for some reason. I'm now just running a Ford Duraspark distributor (which has a reluctor, not points) and I cut off 7 of the 8 teeth, leaving just 1 pulse per cam rev. Still need to get it wired up though. This would be for the sake of running sequential spark. Since right now I'm relying only on a crank position sensor, without cam position sensor, I am forced to run in wasted spark mode.

YOU WILL NEED A CRANK POSITION SENSOR. Your proposed cam position sensor will only output one pulse per cam revolution, which is one pulse for every TWO crank revolutions. This is not sufficient info to accurately tell the ECU what speed the engine is rotating. For example, I added a crank position sensor and trigger wheel with 36-1 teeth (a 36 tooth wheel that is missing one tooth, so 35 teeth and one gap). This equates to 72-2 pulses for every two crank revolutions, which I would say is a typical number.

My four injectors fire in pairs, or 2 at a time every 180 crank degrees. Let me know if you have other questions, and if you'd still like to see my msq.

[wampa]

Oh and by the way I am also running LS2 truck coils. I mounted them on top of the same valve covers I had from my carburated setup, and then ran the OEM plug wires down to the spark plugs. It actually looks pretty decent.