I especially value your input and knowledge since your truck has so much in common with mine, and so today I ask about your headers.
I had always been under the impression that headers messed with the Speed Density computer and it ran really lean. Is this always the case? Did you need the chip? Headers and dual exhaust would be my preferred next mod, but I want to know if I oughtta be saving for a chip too. Due to some tinkering and el cheapo modifying, it already runs a little lean and I'll need a chip someday, but I'd like to take everything one step at a time.
Thanks for your and everybody elses input.

The Law
1989 F-250 HD 4x4
460, C6, BW 13-56
Almost Stock

 

I opened up the exhaust with 1 5/8 headers, off road exhaust, 2 chamber Flowmasters and a ram air with K&N filter on my 88 Speed Density Mustang without it running too lean. I later conerted it to mass air and didn't really see any gain from it. It was a good deal off of a friend of mines wrecked 89. But I will be able to make head and cam changes now.
Anyway, back to your truck, you can always get an adjustable fuel pressure regulator to increase the fuel pressure if you get slightly lean and have detonation problems. The other benifits from the chip would be a slightly longer injector pulse and the timing recurved. I tried one on my speed density system and couldn't tell any difference. A 180 thermostat will richen it up a tad too.
Just some ideas,
Jimmy

 

The Law, my truck doesn't run lean...in fact it runs a little rich. I have purchased an adjustable fuel regualtor and fuel pressure gage but with racing 3 weekends a month, boating, vacationing, etc. I haven't got around to trying the adjustable regulator yet. There are a number of factors that determine how rich/lean your truck runs. Your sensors can be just enough out of calibration to richen/lean your mixture but not off far enough to get a ECM error message. If you have one injector running rich, your O2 sensor will pick that up and adjust the other injectors to run lean.
All in all, I'm very happy with the addition of headers, duals and other mods I've made.
As far as chips go I've read a lot of posts and it seems there are about as many users who were dissapointed as those that were thrilled. You do have to run a higher grade of fuel and most chips to my knowledge are only beneficial at wide open throttle. I personally decided to spend my extra money on gearing other than a chip and I couldn't be happier with my used 4.10's. Now if I was running a turbo-diesel or other turbo/blown gas-powered vehicle...I'd be buying a chip ASAP. Deen

 

Cool, man. Thanks for the info. Now it's time to start saving for some headers.
I've got one of those cheapo code readers where you count beeps and look up the number on the chart and the only fault I get is an out-of-whack MAP sensor. Could this have anything to do with my leanness? I don't know enough about how all the EFI sensors work together to make an educated judgement. The only other thing I could think of is the K&N, but so many folks have them that if that really caused a problem with the computer's mixture I would have heard by now.
BTW, my truck has 4.10's too, and I agree, I wouldn't trade them for anything.

The Law
1989 F-250 HD 4x4
460, C6, BW 13-56
Almost Stock

One last question, with the mods you've made, since I'm slowly following your example and will hopefully end up where you are, what kind of power are you now making? Do you have any dyno runs, desktop runs, educated guesses, et cetera, as to how far beyond stock you've gone?

 

If you really want to understand how your EFI works you need to get the book by Charles Probst called "Ford Fuel Injection and Electronic Engine Control"...I believe you can find it on this site or buy it from Jegs or Summit.
There are a number of sensors that fine tune your fuel system. On my truck I had to change the O2 sensor to eleiminate the "check engine light" that randomly flashed on and off. That solved one problem but I still had terrible fuel mileage. I then replaced the ACT (air charge sensor) and then the ECT (engine coolant sensor...which is NOT to be confused with the water temp sending unit)and my mileage went from 8.5 MPG unloaded to 11.5 MPG. Neither of those two sensors showed error messages. You should be able to change those three sensors for $100 if you do it yourself. The MAP sensors are a little more spendy ($60-$80, I'd recommend you take your truck to Ford to have it checked out as they have a special tool to test it with. Also looking at Charles Probes book he also indicates a faulty EGR valve will give the MAP sensor a false intake manifold pressure to read from...so your problem could be two-fold.
I built my engine for torque since the truck is a work horse and is only used for towing. My DD2000 shows a peak HP of 286 @ 3500 RPM with a peak torque of 487 ft.lbs. between 2000-3000 RPM. That doesn't sound like a lot but I went from towing a 9000 lbs trailer weight up steep long grades using second gear at 38 MPH. I now crest the same grade at 52 MPH in high gear...that's at 5000' elevation. Most mountain roads I maintain 62-65 MPH, much faster than what would be considered safe if I had to panic stop because of a deer, bolders in the road, etc.
Good luck trouble-shooting! Deen

 

Those RV cams, I hear they get along fairly well with our computers. Who's a good manufacturer of these, and how do you suppose that affected your DD2000 numbers? I myself don't use the truck for much besides getting me to work and carrying the occasional ton of bricks or cube of gravel. It's probably seen 4000 rpm 5-6 times since I bought it and 5500 once, never again, because it was scary. So like you, I want all of my power below 4000 rpm's. If the power band spills over into the 4500-5500 range, I ain't gonna cry about it, but it isn't absolutely neccessary.

The Law
1989 F-250 HD 4x4
460, C6, BW 13-56
Almost Stock

 

My cam was a special grind for towing...
Competition Cams part # 34-000-5, FF 5440/5128 H12+4, serial L 9675.
Duration @ .050 is 206 In. 211 EX.
Lift is .499 In. .510 Ex.
A special grind costs more money, if you want to save bucks stick with there High Energy Cams or Extreme High Energy. For towing I wouldn't go above the 260H series. I tried the 268H series in a 1978 F250 with a 460, C6, 3.55 gearing and was dissapointed...the powerband was too high (3000 RPM and up) for a tow rig. I found the truck to just barely come into the power band and the tranny would up-shift to the next gear. I'm sure the 268H would have been allright if I had change gearing to 4.11's and installed a 2400 stall converter and a shift kit.
My next rebuild I would change three things. I'd spend the extra money and go with the CJ size valves, I'd port the exhaust to match the headers, and I'd install the metal valley cover to keep the hot oil off the stock EFI intake. Deen