As I'm sure most of you guys are aware, the 87-93 EFI 5.0 F series engines were rated at 180HP, but in 1994, ratings jumped to 205. The only real difference between 93 and 94 was a cam swap to the F4TE cam. This cam had 256/266 duration and 0.422/0.448" lift at the valve, compared to the 244/256 duration, .379/.395 lift offered by the 92-93 roller cam. With a 25 horsepower jump with just a cam swap, I'm sure the only reason why people aren't swapping in the F4TE cam, or even a Mustang HO or better cam, is the fact that all these better performing camshafts use the HO firing order, 1-3-7-2-6-5-4-8 instead of 1-5-4-2-6-3-7-8.
Up till now, if you wanted to run an HO cam, you'd need to switch to a mass air setup with sequential injection. One of these reasons was due to the fact that speed density, found in all 87-93 F series 5.0L engines, does not take well to extreme camshaft change. Another reason is the fact that all the pre-MAF Fseries 5.0L engine management systems used batch fire injection. In batch fire, a complete bank of injectors fire each time one of the cylinders on that bank is firing. All 8 of the fuel injectors are powered by a single hot wire, and only two grounds exist: one shared ground for the passenger side injectors, and one shared ground for the driver's side injectors. On the standard (non-HO) firing order of 1-5-4-2-6-3-7-8, the computer fires all the injectors on the passenger side (1,2,3,and 4) during the firing of the #1 cylinder. For the next cylinder in firing order, cylinder #5, the computer would fire all cylinders on the driver's side (5,6,7,and 8), and so on and so forth. Giving the pattern PDPPDPDD (P=passenger's side, D=driver's side). Now look of the difference in firing order between HO and SO, and imagine an HO cam in a batch fire engine. As you can tell by the firing order differences, when the 3rd cylinder is firing on the HO firing order, the batch fire system would actually by firing the injectors on the OPPOSITE side of the engine. This would happen not only on cylinder #3, but also on #4, #5, and #7. I don't think I need to explain how this is a bad thing. However, I think I've come up with a way to make a batch fire HO cam swap a reality.
Once drawn out on paper, it became clear that by wiring injectors #3 and #4 to the driver's bank, and wiring injectors #5 and #7 to the passenger's bank, the batch fire system could fire the appropriate injectors for an HO firing order, while still using a batch fire method. In this modified version, the passenger side common bank of injectors would now be #1, #2, #5, and #7, while the driver's bank would now be #3, #4, #6, and #8. Putting that into the HO firing order, we get: PDPPDPDD, which is the same as the current batch fire order for the stock non-HO cams! What this means is, you don't need sequential injection to enjoy the 20+ horsepower gain to be had by swapping an HO cam in a 1992-1993 F150!
Yes, there's still the original problem of speed density and its lack of adjustability, but reason would state that with stock heads and intake, the volumetric efficiency of the engine has not changed enough to adversely affect the operation of the speed density computer. What speed density thrives on is manifold vacuum. As it has been already shown in the 1986-1988 Mustangs, the Mustang HO camshaft plays well with a speed density computer, and the F4TE roller camshaft, found in the 94-96 Fseries/bronco 5.0L and 351w and 95-2000 5.0L explorer, is even milder than the stock mustang HO cam (the specs of a stock mustang HO cam are 266/266 duration and 0.444/0.444 lift), so I'm confident that a stock F150 speed density system can cope with an F4TE cam upgrade without risk of running the engine lean, or suffering bucking, jerking, irratic idle, or even tripping a CEL, all the while enjoying a nice 20 horsepower boost afforded by the better breathing cam.

Thoughts/questions?

 

Are you kidding me? The only real change was the cam... no. The only real change was the MAF system. You won't get the full benefit of the cam without switching to MAF.

 

Your next homework assignment will be to explain how the ECU has any idea how the PIP (Stator) signal accommodates the Cam duration modification in relation to injector function. In music, I think they call it a refrain or delay. You still play the note, but slightly off it's normal syncopation. I ran the MAP/MAF argument up your flagpole on the other Forum you posted on (small world!). But, Your getting there! Keep up the good work! Here' a link that explains better. http://www.fordfuelinjection.com/?p=25 What it your base timing set at? This is something the ECU & all components can all agree upon. You should be aiming for 16 BTDC, w/o ping, w/ 87 octane!

 

Simply not true. The maf is not offering more horsepower over batch fire, at least not in the form of the benefit of sequential injection or more precise air metering. If Ford's original speed density system were that far off to afford a 20 horsepower gain solely from a switch to precise air metering, all the old SD motors would have destroyed themselves long ago do to such a poor tune. Now, I won't deny that the mass air equipped f150s most likely have optimized tuning of fuel and ignition curves to take advantage of the cam change, but it's the cam, and not the tuning or MAF, that provides the vast majority of that 25 horsepower bump.

 

You mean other than the feedback loop of the O2 sensor? If the system runs lean, the O2 will indicate as such, and the EEC-IV will compensate by increasing injector pulse width. Usually the computer can increase pulse width up to 20% over base programming. Eventually these changes are adapted into the standard tune on the computer, meaning they are incorporated even in open loop and WOT. Only by disconnecting the ECM from the battery for a few minutes will it reset back to base config. I'll agree that it won't be as optimal as a custom tune, but the Mustang guys have done E-cam swaps on their speed density systems and had positive results, despite the non-optimal SD tuning.
Now you may think that this won't work as this page talks about:
http://www.fordfuelinjection.com/ind...&submit=SEARCH
However, thanks to the single O2 sensor the F150 uses and it's unique positioning that allows it to sample the O2 gasses from both banks of cylinders at the same time, giving it an overall rich/lean picture, the F150 setup is immune to the problems of injector wiring swapping, making a batch fire HO possible.

As to the other Q, my 94 is running only 13 degrees BTDC. I wanted to play it on the safe side, as I do tow with it.

 

The method of monitoring amount of air inducted & how the injectors are triggered are two separate issues, & "JCMS" doesn't appear to be confusing the two to me. As I mentioned in your thread on the other other forum, Air flow (or the restriction of) is exactly how Ford detunes the engine to curtail the amount of developed HP. Fuel trim added is based on the amount of inducted air! Ford application of SEFI & MAF are complimentary & coincidental in development & deployment, however, they are not co-dependant & they both rest on their own merits. That being said, without accurately metered, increased air induction, any additional fuel is best left in the tank, & any additional ponies (HP) will be waiting for you in the barn till you get all your ducks in a row!

 

We'll have to agree to disagree. You seem to be under the assumption that SD is not adaptable to any change in air flow. I respectfully disagree. In this scenario, where the cam change is a relatively modest upgrade, SD should be able to give a reasonably close amount of fuel for the air charge. Any differences will be adjusted for by the O2.

 

The Hego sensor modifies the duration that the injectors remain open (pulse width) in order the maintain the ECU mandated 14.68:1 air to fuel ratio. It has no effect on the moment of triggering or syncopation thereof. You need to be running 16 BTDC to obtain the full benefit of the timing bump. In my experience, there's a few minor mods required to function safely at that additional base time advance. But all of these contribute to the welfare & longevity of your engine anyway.I make frequent trips, where I run through both tanks nonstop (700+ miles) at 80 mph average, w/ a 1,400 lb. payload which includes a Harley strapped to the bed & the A/C blasting. It likes it, and so do I. I had that speed documented on the last trip. $628 + traffic school.

 

In this scenario, I truly feel the moment of injector firing is a non-issue. As the rpms and load increase on an engine, the injector duty cycle increases. At max load/rpm, it's not uncommon for the duty cycle to be almost 80%. At that point, the injector is almost running continuously, where in comparison the intake valve is only open for just a portion of the injector's duty cycle, all other times the injector is spraying onto a closed intake valve. At max duty, it matters not "when" the injector starts spraying. I can see some small issue at no load, low rpm, such as idle, but then again, the difference in duration between the 92-93 roller and the F4TE is only 10 degrees, so the intake valve opens only 5 degrees sooner than previously. Such a small change will most likely not adversely affect the operation of the engine.

 

Blah blah blah blah blah. Do what you want, it's your truck. We all know better. There's a reason everything is MAF now.