Speed density batch fire injector confusion
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Joined: Aug 2002
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From: Utah
Speed density batch fire injector confusion
Could someone please help me understand the batch fire injector on the speed density trucks?
If I understand it correctly, on batch fire, every injector on the bank that is firing will inject fuel at the same time. On the sequential fuel injection, only the injector on the cylinder firing will inject fuel.
If I have that correct, wouldnt all that fuel just be pilling up in the intake runner until that intake valve opens before the cylinder fires?
Wouldnt converting to sequential fuel injection be significantly more fuel efficient? I would think it would be worth more than just a couple MPG's.
Or am I missing the boat somewhere?
If I understand it correctly, on batch fire, every injector on the bank that is firing will inject fuel at the same time. On the sequential fuel injection, only the injector on the cylinder firing will inject fuel.
If I have that correct, wouldnt all that fuel just be pilling up in the intake runner until that intake valve opens before the cylinder fires?
Wouldnt converting to sequential fuel injection be significantly more fuel efficient? I would think it would be worth more than just a couple MPG's.
Or am I missing the boat somewhere?
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Joined: Jun 2006
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From: Ottawa, Ontario
Yeah you would think so but it doesn't work out that way. A bit of extra fuel in the intake tract has the effect of preventing carbon buildup on the intake valves, Ford had to add port injectors to the newer direct injection motors for that exact reason, carbon buildup got so bad in 100k miles that the intake valves were hanging open resulting in loss of power and backfiring.
As for fuel milage, in stock tune the batch fired trucks usually do a little better than the SEFI version believe it or not, sequential injection has the potential to do better but Ford didn't add the extra code needed to truck PCMs because these were work vehicles not high performance or economy vehicles. If you do a MAF conversion using a Mustang PCM then there is some extra programming in some of them for a lean burn mode that activates on extended cruises at a steady speed... such as longer highway trips, and that can produce better than average mpg under those conditions.
As for fuel milage, in stock tune the batch fired trucks usually do a little better than the SEFI version believe it or not, sequential injection has the potential to do better but Ford didn't add the extra code needed to truck PCMs because these were work vehicles not high performance or economy vehicles. If you do a MAF conversion using a Mustang PCM then there is some extra programming in some of them for a lean burn mode that activates on extended cruises at a steady speed... such as longer highway trips, and that can produce better than average mpg under those conditions.
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More Turbo
Joined: Aug 2002
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From: Utah
Thank you for the education. I was trying to decide if converting it would make it to the next round of purchases. I will leave it as is. For now at least. 😁
There is a ton of info here about speed density vs MAF, but I couldn't find an answer to that specific question.
There is a ton of info here about speed density vs MAF, but I couldn't find an answer to that specific question.
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Joined: Sep 2001
Posts: 11,958
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Yeah you would think so but it doesn't work out that way. A bit of extra fuel in the intake tract has the effect of preventing carbon buildup on the intake valves, Ford had to add port injectors to the newer direct injection motors for that exact reason, carbon buildup got so bad in 100k miles that the intake valves were hanging open resulting in loss of power and backfiring.
As for fuel milage, in stock tune the batch fired trucks usually do a little better than the SEFI version believe it or not, sequential injection has the potential to do better but Ford didn't add the extra code needed to truck PCMs because these were work vehicles not high performance or economy vehicles. If you do a MAF conversion using a Mustang PCM then there is some extra programming in some of them for a lean burn mode that activates on extended cruises at a steady speed... such as longer highway trips, and that can produce better than average mpg under those conditions.
As for fuel milage, in stock tune the batch fired trucks usually do a little better than the SEFI version believe it or not, sequential injection has the potential to do better but Ford didn't add the extra code needed to truck PCMs because these were work vehicles not high performance or economy vehicles. If you do a MAF conversion using a Mustang PCM then there is some extra programming in some of them for a lean burn mode that activates on extended cruises at a steady speed... such as longer highway trips, and that can produce better than average mpg under those conditions.
I know that the Mustang A9L and A9P are the desired ECU / PCM for MAF conversions. Can you use one in a 94 5.0 or 5.8 swapped truck with a 4R70W? Somehow I don't think it will work since Fox Body Mustangs didn't have that transmission and used the AOD instead.
A friend of mine did use the A9L in a 5.0 347 stroker 5 speed truck, but that is the only first hand experience I have with those swaps.
https://lmr.com/products/what-is-an-a9l-computer
Hotshot
Joined: Jun 2015
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No. The Mustang computer would not be able to control the transmission so you would need a stand alone computer for the transmission. I have a Ford Motorsports conversion with an A9L on my truck. Hopefully it won’t be too much longer and I’ll be able to find out how it handles the 351 versus the 302.
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Joined: Sep 2001
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The ‘94 Bronco (5.0L/ E4OD) was a MAF truck. What was swapped in: the V8 or the transmission? Wouldn’t a 4R70W equipped truck also have been MAF? If so, then you should be able to find a factory PCM.
No. The Mustang computer would not be able to control the transmission so you would need a stand alone computer for the transmission. I have a Ford Motorsports conversion with an A9L on my truck. Hopefully it won’t be too much longer and I’ll be able to find out how it handles the 351 versus the 302.
No. The Mustang computer would not be able to control the transmission so you would need a stand alone computer for the transmission. I have a Ford Motorsports conversion with an A9L on my truck. Hopefully it won’t be too much longer and I’ll be able to find out how it handles the 351 versus the 302.
My truck is already MAF, What I was getting at is that if the fox body one is best for performance and possible efficiency it might be worth using in a stock MAF truck if it would work, but it looks like only a manual trans truck can use one. Having to use a stand alone transmission ECU would make that whole idea a waste of time unless building a full project truck etc.
I'm interested to see how your motor swap turns out. I would think it'll be fine since the stock 94 MAF 5.0 ECU can run a 5.8. That's what I'll leave in place to run my 5.8 if it ever gets done. That has been back burnered many times for other projects.
Logistics Pro
Joined: Aug 2014
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Still working on my SpeedDensity DistributorLess SequentialFire COP.
On a 1994 351 E4OD Flareside.
BatchFire vs Sequential, probably does not matter on a stockish engine, MAF mpg might be better if you never rev over 2000.
After 3500rpm+, fuel injectors start running above 51% open, meaning they are open more often than closed.
If I run my engine with fuel injectors open 80-90% of the time, Batch fire vs Sequential fire isn't going to matter, since they are closed 10-20% of the time.
If you take the percentage of time that an injector is open, your going through the same amount of fuel regardless of Batch vs Seq.
Now, if you can tune each individual fuel injector cylinder, using O2/Heat sensors on each exhaust, you could different MPG and different power.
Cheers, happy friday!
On a 1994 351 E4OD Flareside.
BatchFire vs Sequential, probably does not matter on a stockish engine, MAF mpg might be better if you never rev over 2000.
After 3500rpm+, fuel injectors start running above 51% open, meaning they are open more often than closed.
If I run my engine with fuel injectors open 80-90% of the time, Batch fire vs Sequential fire isn't going to matter, since they are closed 10-20% of the time.
If you take the percentage of time that an injector is open, your going through the same amount of fuel regardless of Batch vs Seq.
Now, if you can tune each individual fuel injector cylinder, using O2/Heat sensors on each exhaust, you could different MPG and different power.
Cheers, happy friday!
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Joined: Aug 2002
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From: Utah
That makes sense. Thank you.
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