you all are missing the point.

this is a diesel application - engine power is NOT controlled by air. It is controlled by the amount of fuel injected.

you will not find a throttle plate on this vehicle.

 

I looked myself with no result. Motorola may be out of all electronics but cell phones by now.

By the way, I've got a Honda Fit the does fly by wire for the throttle. It's twitch as hell without the elastic wire and bellcrank mechanism. That probably means no shaft end to grab at the throttle plate for a mechanical cruise control. I got the cheapo model with cruise, so I have no idea how it's done (it is available for the Fit - I just did not want fancy wheels and silly trim package that come with it).

 

Sorry, I stand corrected I missed the diesel part in the original post.

 

Sorry all for dropping the discussion. Major deadline at work! So ClydeKrash - my original doodlepad sketch had two SPDT switches to isolate "my" circuit from the truck... I think that still might be the best strategy. I was just thinking for simplicity, I could avoid cutting any wires and just "add" voltage. I haven't had a chance to play with the actual voltages while the vehicle is running. I think I need to do this first. I got the pig cable so I think I need to tap each wire, figure out how the voltages read under different throttle levels, and make sure I can bump up the RPMs by adjusting voltages accordingly. Although I felt like I thought this through, it's obvious that I have to work out a few specifics before progressing (if at all).

I'm on travel next week, so that'll give me some time to muse. I work in a technical field, so I naturally found the PID algorithm information on the web very interesting. I've done quite a bit of programming during my career, but always with PCs and high level languages. I think PIC controllers are really cool, so I'll probably continue investigating this even if it's not a lot of bang for the buck!

Thanks again to all for replying.

 

One thing to consider is that if the throttle pot (TPS) is at one end of it's range of travel, then injecting voltage into the wiper terminal part of the circuit could burn up the throttle pot. Definitely limit the current into the TPS circuit to avoid doing damage to your vehicle! Can you find and post a wiring diagram of this part of your truck?

__________________
--- The days of the digital watch are numbered. ---

 

kchriste, I"m on travel this week, so I don't have my service manual with me. What you're saying is what worries me. I was thinking about putting diodes into the current path to keep current from flowing where it shouldn't, but then you get some voltage drop so I would imagine it possibly messing up the throttle response. I think perhaps isolating the entire circuit with switches might be the best insurance. Still, I hear what you say about the current issue. As I remember the wiring diagram, voltage from the TPS/throttle "goes" directly to the vehicle's PCM. I would guess it should be high impedence if it's meant to monitor voltage? As you might guess, I've taken electronics courses, but don't have very much practical experience designing real-world circuits!

Thanks,
Tom

 

Have any of you ever heard of the new adaptive cruise control that they are putting in luxury cars/busses?

Basically you set the maximum speed that you want to go, and it will adjust the speed below that point to remain a safe distance behind cars in front and will slow down to make turns. It detects vehicles in front through video cameras or in the more expensive versions radar. It also has a yaw sensor that detects whether or not the vehicle is turning.

Its a more complex system, but it would be really *really* cool if you made it work. =) I guess there are also many more possible points of failure, but its a neat idea nontheless.

 

Stellacore - first thing's first! I gotta build the simple prototype first, then get fancy - I need a the noob version!

To answer some questions on the thread, here's the info on how the TPS/accel dictates the engine RPM:

See post #6:
http://www.powerstroke.org/forum/99-...tml#post141915

And post #10 here shows how you can alter throttle using a resistor and relays (like CydeKrash suggested):
http://www.powerstroke.org/forum/99-...html#post89440

I need some deadline-less time and to be home to investigate further. I think I'll rework my design to incorporate ClydeKrash's suggestion of using switches (or relays like the idle mod) to isolate my whole circuit. Anything goes funny and the vehicle reverts to it's former self. I also need to tap the RPMs as a previous post pointed out - if it pops out of gear I could be screwed. My truck is older, but has very low miles, so I want to keep it running for a long time!

Thanks all. I'm sure I'll be working up potential circuits after Wednesday!

 

what is really important about ACC is that even with only 20% of the cars on the road equiped with it, traffic jams will be significantly reduced. The reason is that ACC allows tighter tracking of the vehicle in front. Braking and speed-up have significantly less dead time. The typical rolling slowdown (standing wave) will be eliminated.