I installed a new TPS and that's what the problem was. Apparently the computer wasn't getting correct readings from it, which is why I ended up screwing with the stop screw.

Doesn't really matter anymore. Truck's running fine. Problem solved.

 

Man.. I got a tuner and I know what it is capable of doing. The thresholds for switching from closed to part throttle and then to wide open throttle are fixed numbers(scalars) that never change under normal conditions but can be editied with a tuner.

 

Paul O,
I do not know about those tuner things as I only work with stock trucks.
I was just going by what Charles O. Probst said in his two books on "Ford Fuel Injection & Electronic Engine Control" and what is on the "fordfuelinjection.com" site.
I guess they are both wrong.

 

OK.. you forced me to investigate this a little more too and you are right in the way the system calculates the switch between throttle stages. I have seen it mentioned in a lot of places that closed throttle still has to fall somewhere between 0.6 and 1v or there abouts but I don't see any mention of that in my tuner software at the moment. The formula used to switch to WOT for example on the processor I have is THPB5 + HYST2 + Ratch where RATCH is the lowest TPS measurement since the last engine start, HYST2 is the hysteresis range, and THPB5 is the breakpoint voltage relative to ratch. For these last 2 parameters I have values of 0.025v and 2.775v and these can be edited with tuner software though they won't normally need to be.

 

As I tried to say above I do not know about this for sure as I was just going by what I read in the two books by Charles O. Probst and on the "fordfuelinjection.com" site.

I have never seen the software source program that any of these computers run. I do not think anyone else has either outside of the Ford and Intel software people.

The program may be different each year but I do not think so. I think they just change the look-up table for each application.

 

I know there were a lot of different strategies used over the lifespan of the EEC4 system so it would be silly to suggest that anthing would apply to all of them. I know for the processors I have investigated so far that they appear to use the same scalars, functions, and tables for the most part but with unique values for each vehicle and powertrain in use. I have also seen evidence that there were some changes to a small number of formulae used over the years for whatever reason and this results in some scalars or a table being added or removed. Overall though the processor logic is a lot more complicated than I ever though necessary and I'm still learning something new every time I take the tuner for a spin.