Well, were finally back in business. Got the truck fired up and running with the new heads and should be on the dyno this week. I've been doing some preliminary tuning with the BBK adjustable fuel pressure regulator and reading A/F changes with the LM1 wideband 02. We definitely picked up airflow, with the stock fuel pressure regulator the truck was scary lean (16:1) at mid and upper rpm range. I put on the adjustable regulator and started cranking down on the thing and still am not able to get a decent A/F ratio. The richest ratio we can get at full load and high rpm is in the upper 14's, when ideally the engine should be closer to 12.8-13.2:1. We are loosing some power for sure, but to be fair we will back to back test it as is and see what it will pull. It feels stronger and throttle response was significantly improved. The truck sounds completely different throughout the rpm range. I hope we can at least get enough gain to make all this worth while on a stock fuel pump, ecu, injector set-up but to maximize the airflow gains we need more fuel. I haven't hooked up a fuel pressure gauge to check what the pressure is doing under load, but I suspect we are either out of pump (sounds hard to believe but I could be wrong), have a clogged fuel filter or are out of injector. I plan to change the filter before the dyno session and see if anything changes. Hopefully we can figure this out. Any first hand experience from you guys pushing decent power with the stock pump?

Stay tuned....

 

You may be the first to have reached this new wilderness

 

ill be checkin this thread out nonstop. my trucks bout identical but its ext cab. my plans are stickin a set of 69 429 heads on it and matching the intake to them. i hear that makes quit a power boost with a little bit of low end tq lost but made up for with the top end.

 

Looking real quick at the top of the thread, you didn't mention if it was a SD or MAF setup. Might not be out of fuel pump or injector, but if SD the fuel maps might not have an answer to the airflow.

Just my idea...and a post to subscribe to the thread.

 

The truck is speed density. Even though, I would think bottoming out and adjustable regulator would have more effect to the map than it did. This ecu must have some open loop capabilities because as I kept adding pressure the initial start up after adjustment would show a more rich idle condition (10.8 or so) then after a minute or so of normal driving the A/F would bounce right back to 14.7 at idle.

 

In closed loop it uses the O2 to trim A/F ratios back to stoic but in open loop it's just using the default maps referenced to manuifold pressure so the only way to get more fuel at WOT is to increase pressure across the injectors. I suspect you're running out of pump, as far as I know all these trucks use the same one and it's not super big.. probably will only support 300hp give or take.

 

Sorry, meant closed loop above. Still I was surprised the ECU could trim back fuel at part throttle cruise and idle as well as it is. Are these pumps comparable to the same era F150 pumps? I know of a few turbo 4 cyl. guys who have used the F150 pumps up to the 300whp range, and I know we are not anywhere near that.

Bo

 

Well, I thought I would throw it on the dyno for the hell of it and ended up wasting a bunch of time. No matter what I do to the fuel pressure, I just can't get the A/F anywhere near where it needs to be. To make it worse, the dyno's wideband 02 was still broken so I was reading off an LMI trying to tune with no reference to rpm other than rigging up the LM1 next to the tach and recording with a video camera. To top it off the video I tried to keep to use for tuning a chip somehow disappeared from my camera to the computer. The "richest" I could get at peak horsepower was about 15.5:1 A/F. Even then the A/F curve was all over the place. The dyno graph looks just like the A/F curve, very bouncy and all over the place. Either I have a major fuel delivery problem or these speed density systems just can't compensate for mild mods and a little head porting. I was expecting we could just add fuel pressure to solve the problem but now it looks like a custom tuned chip is in order. All in all, at this point without a tune I don't recommend porting the heads on your truck if you already have some mods done. All said and done we picked up 10hp and 5 ft.# torque back to back... take it for what it's worth. After I have some time to relax I will look into a tune and see what we can get out of it but right now I need a break! Thanks for following the thread.

 

Wow, that sucks. I am sorry to hear that all your hard work only got 10&5.

 

No there's something wrong there you should be able to make the motor run rich, put a pressue gauge on the fuel rail and you'll know where the problem is.

 

I'm with Paul on this one. Toss a gauge on the rail to verify what the pressure is. The Lightning guys make more power than you are, and plenty of mods, with the same fuel delivery system.

I cut this from my Ford service manual to verify that last statement:

The in-tank mounted fuel delivery module containing the fuel pump is capable of supplying 105 liters (27.7 gallons) of fuel per hour at a working pressure of 270.0 kPa (39 psi) for the 5.0L, 5.8L and 7.5L MFI engines. The fuel delivery module can supply 90 liters (23.7 gallons) per hour at 380 kPa (55 psi) for the 4.9L MFI engine.

Your 7.5L engine uses 24 lb. injectors. You should be able to supply your engine with plenty of fuel given the few mods you made. Granted a custom tune would help with extracting every extra HP, but left as is you should not be running this lean.

 

Well that's "good" news I suppose, I'll start looking for a major problem.

 

I don't have a big block truck yet but one's in my future. Looking forward to the final results.

 

Can anyone verify this? I keep getting conflicting answers. Today, I *thought* I finally came to the conclusion that our cam timing is retarded some 8* so I went ahead and ordered a whole new timing set...and then I read this...ugh.

Anyway, thanks for the great info in this thread! I'm in the process of doing a SD to MAF conversion....had to pay fordmuscle $20 just for the write up but it was worth it...I'll post it up here once I get the time. Think I'm gonna hit up the local junkyard tomorrow and see what I can find. One thing I'm going to do differently in regards to the conversion is I'm going to install my wideband and run an AEM ECU (30-1400) instead of the stock mustang ECU....I've run my lil 4 banger honda on an AEM ECU tune that I made myself for the last year or so and love AEM...that way whatever mods I do to the 460 I can just simply hook up my laptop and adjust the appropriate timing/fuel maps, respectively. With that said, does anyone know how these ECU's come out? I went out and checked tonight and it looks like it's stuffed behind the parking break pretty well...any advice greatly appreciated!

 

They come out from the engine bay