Got a lesson over the weekend and thought i'd share to save others the time if the same scheme develops in their thoughts.

Have an old 96 7.3l. The APS is the Dorman replacement and has been on the truck since I bought it used. some days, the Check Engine (red) light on the main instrument panel will flash right after the engine starts. Thottle pedal still controls the engine but not smooth.

I got a couple hours this weekend and dove into it. Bast as I can tell, it's still the original pedal assembly. Pulled it and noted that the idle position of the APS is well off the low stop of the resistor. As the APS doesn't have slots for adjusting is position on the bracket, I toyed with improving them. During the inspection of the pedal, I noted there was enough space to add a 'rotated' set of holes to adjust the APS to permit more travel.

After a bit of scribing, drilling, and tapping, i reinstalled the APS and then the pedal assembly. Initial resistance (at idle) on the APS was now like 400 ohms where it was originally just under 1000. Key in and startup. No response from the pedal. APS remounted using original screw holes.

The post mortem - checked the FORD Service CD - looks like the "expected value" from the APS (using a 5V DC reference voltage) is 0.4 to 1.2V DC, at idle. Looks like with the APS i have, using the original mounting holes, I'm right at the upper end of acceptable. The new holes "turn down" the potentiometer too far so the ECU disables the throttle pedal.

So, if you wanna "dial in" your APS, I'd suggest filling the body and adding radial slots - relocating the mounting holes just won't provide the desired effect.

 

look around on here for the "hot foot" mod.

That info might help you also.
I know you got it fixed, but for some extra reading.

 

Thanks for the suggestion - did a quick search and 'Geep's" microadjuster for the IVS may do the trick. Could also be the Dorman sensor just has a lot of time on it and the "idle transistion" zone on its wiper is worn...think I'll wait til next month - the budget should support the extended s/w for the AE adapter - nothing like realtime data.

 

Talyn: Did a search for "hot foot" mod and found a few posts but every link I found has gone stale.

Looks like some may have been trying to change the transfer function of the resistor network. That's not what I was trying to do. I just want to get the ecu to recognize the go pedal movement earlier in its travel so it goes "off idle" sooner.

Looks like the near term fix will be 'Geep's "microadjuster" approach - anybody have any "lessons learned" on doing this - thread size for the stop, in particular?

 

The hotfoot mod is pretty simple, you drill out the holes in the IVS so that you can rotate it to get the go pedal to respond sooner... as best I can recall. It accomplishes the same thing as ROENTGEEP'S microadjuster, just a different way of skinning the same cat.

 

You can search my older topics. I had a pretty detailed write up and pictures of my whole modification. Made a big difference in response

 

Im sure its a different way of skinning the same cat, but the microadjuster makes a BIG difference, the other is operator sensibility dependent.

LOL

 

c00nhunterjoe - thanks for the input - did a search and did find a thread on the mod but not pics...either way, there was sufficient detail to understand what the mod is trying to obtain.

In retrospect, I was trying the pedal mod to get to a similar state to what Roentgeep's microadjuster will deliver....I was trying to maximize the output voltage swings from the APS by minimizing the travel where IDLE VALID is true. My approach yielded an "out-of-bounds" value for the APS at idle; similar results appeared to occur for some when doing the pedal mod. I think Joe's post described the preferred end state - min pedal movement with the IDLE = TRUE and max voltage swing with pedal arc (without exceeding the ECU's predetermined fault values).

ROENTGEEP - what thread size stud did you finally select? Looks to be of the FINE pitch variety.

Thanks to all for the inputs.

now to tackle that squeaking steering wheel

 

I like the microadjuster method myself, much easier to fine tune. I actually need to get of my butt and do this mod!

 

I really dont know, but I think like you, it looks to be FINE thread. But I dont think it could make to MUCH difference to fine tune between them in the practice. If you are very intersted in the pitch, I can mesure it for you, let me know.

Yes you should do it, your are going to like it.

 

Jose: No need to measure....I'll just dig thru the SAE box and see what is 'readily available'. Thanks for the offer though. Any other pointers??

If anyone's interested, I'm gonna try this, later in the week. If you'd like pics & a writeup, ask over the next day or so & I'll tyr to accomodate.

 

Okey dokey. I think it could be good to see the pics and the writeup for future reference.