2nd Gen Non-Engine/Transmission Installing a dash mounted throttle...

[rspinks]

I'm trying to understand the operation of this PS high idler better: With no throttle pedal input, if you just turn the idler on I assume the idle stays @ 750rpm, and as you turn the knob to fully clockwise the engine speed will go from 750rpm to 1550rpm. Does the engine govern to the set RPM, or will the RPM change with engine load? Does the throttle pedal "damping" effect vary with the knob position, or do you just get a fixed amount of damping regardless of knob position?

 

[geusterman]

Ok, Ok, my turn to talk. Are you guys saying that the electronic idler is good to 1550 no-load rpms and that it cannot be used as a cruise control or back-country idler if a load comes against the truck???? Right? So really, I want the mechanical idler like rspinks has so I have an idle or engine speed that is fixed no matter what--like a tractor. Is that how yours works, rspinks? Thanks--GE

 

[JHansen]

Holy cow my head is spinning here... ... lemme do a memory dump here and see if what spills out clears up things or makes them worse ..... !



Let's say for discussions sake the truck idles at 750 rpm (Rich picked that # and I kinda like it-remember arbitrary # here so if the true idle speed is 800 rpm don't send me hate mail). If you click the idler on-it raises the idle RPM probably 25 rpm or so. But it remaps (again Rich's learned speak ) the TPS output so that full throttle pedal is probably around 75% or so of normal-and everything in between is linearly spread over that range. The higher you turn the knob-the lower the maximum throttle value is-but the linear map still applies. You can still hit governed RPM just like everything was peachy keen. However I have not tried to drive there to see how things would react (ie trip the dreaded check engine light).



If you use the PS high idler to set a desired idle speed it will stay there-minus minor fluctuations from the AC clutch tripping on and off-but no mean jumps in speed like you'd get from a fixed throttle setting on a carbureted gasser.



In my experience (and it was so long ago that I can't even remember how fast I had the idler set) using it as a steady-state backwoods cruise worked fine until the truck tried to climb an incline. The computer feeds in throttle attempting to maintain engine RPM-just like it does at base idle or a fixed foot pedal setting. However somewhere in the loadup it gets confused-here's an opinion why-the ECM thinks you're idling along at rest-but it's gotta be getting a vehicle speed signal back through the PCM as well as seeing load factors all of a sudden from RPM and MAP sensor readings. To further confuse it, as I understand it there's a microswitch in the TPS that tells the computer the pedal is at idle. So in my esteemed opinion-and keep in mind my opinion and $2 won't buy you a beer in these parts it's no wonder the check engine light comes on..... Something in the idle validation circuitry is the reason why the PS high idler has to be adjusted to a max of 1550 rpm with the trim pot inside. It will work at higher speeds-I had a little calibration error for a period of time -but eventually you'll throw an idle validation code.....



Somebody else other than me should try using it as a backroad cruise to see if they get the same results-worst thing that can happen is setting an idle validation code and Check Engine light for a few keycycles. This way we'd know if my experience is valid or skewed by something unique to my truck.



If you're wanting a backwoods cruise control-the mechanical cable setup is the way to go. If you want a plug-and-play high idler-the PS solution is the best IMO. I guess I should have asked you that off the get-go George before I started raving about the PS box-for my application it was the hands-down best solution-but maybe not for you?



So who have I totally confused now with this ramble?



Jason

 

[rspinks]

GE, I just had a look at how mine works. It's another cable that runs right along the throttle cable and attaches to the same arm on the throttle position sensor, thus doing exactly the same as the throttle pedal. You have to adjust it to compensate for load changes, so unfortunately it's not like a governor at a set RPM. Plus the adjustment is really fine so it takes alot of cranking to change the RPM's much.



Rich

 

[geusterman]

Jason and rspinks, I think this is clear. There is a mechanical throttle that we used on dump trucks and tractors which screwed to the right to increase throttle but also had a quick on or release by pulling or pushing it, if I remember correctly. This type of throttle we used on our old jeeps of yesteryear for plugging along over bumps so our foot did not bounce up and down on the foot throttle adding irritation to the trip. It could work out on the freeway as well (albeit not as good as an electronic cruise control) but I could kill a couple of birds with the one thing. Gopher and prairied dog shooting as we lurch over the prairie is an issue as well as those long drives. Where did rspinks throttle come from? Thank you Jason for helping me understand your product and turning me onto a Great Falls guy. GE

 

[illflem]

Don't know how a 24 valve cruise control compares to a 12 i. e. vacuum servo vs. electronic but here is a cheap, easy way to convert a vacuum type cruise to a constant rpm cruise, even easier than a manual cable http://216.235.147.117/forums/showthread.php?s=&threadid=6255

 

[JHansen]

addendum!

After I posted about my experiences using the PS high idler as a backwoods cruise, I got to thinking a little more. If memory serves me correctly, the time I tried to use it I was in a pretty high gear (thinking 4th). That alone could have caused too much load thereby throwing the code. If I get a chance this morning on suitable terrain I'll try it in a lower gear (1st or 2nd) to see how it works... .



Bill, the 24 valves used basically the same cruise setup as a 12 valver up to the 2001 model year with manual transmissions. These ones are servoless-all the control is done by the ECM electronically so you've either got to manipulate the TPS signal or manually pull on the throttle arm. There is a kit from Diesel Services Group that ties into the servo electronics to make it function as a high idle actuator-this is actually the kit I bought first. But I would have had to add the servo-and nobody knew exactly what was gonna happen when I plugged the servo into the factory wiring and all of a sudden there's 2 separate entities trying to control the cruise-and it required a lot of wire chopping and splicing which I was not prepared to do to a new truck. So I sold it to Marc Kuzik (MDKram)-he's happy, I'm happy so everything's cool!



Jason

 

[rspinks]

Mad Max posted a timely thread on the 24v Engine & Drivetrain forum, too bad I don't know how to link to it. It's called Cheap High Idle, Oem Feature.



To summarize it sounds like the ISB has the governed high idle function built right into the ECM, just needs to be programmed.



Rich

 

[rspinks]

Info on my mechanical high idler

Guys, I just talked to my dealer and found out they source the high idle cable and rotary knob from a local jobber under p/n 58R5, dunno who the mfr is however. They also source the throttle arm to cable clevis connector locally and the shop then installs it.



They said they go this way instead of electronic module because it's simple and only costs $66 in parts versus several hundred $ for the electronic versions. It would be a really simple install if you could source the correct parts.



RS

 

[Rob Thomas]

RS,



The PS high idler, is very simple to install and does NOT cost several hundred dollars, it's less than $200, the PS installs in less than 1/2 hour.



As far as the OEM high idle feature, way to much criteria has to be met in order for it to work, and most people who have gotten it done, complain that it just doesn't work. FWIW





Later. Rob

 

[rspinks]

Rob,



I hear you, I was just repeating what my dealer told me. The install time for electronic would probably be shorter. Note that "less than $200" in US currency converts to several hundred Canadian.



Not surprised at the OEM high idle problems, otherwise everybody would be doing it. Would be great if it worked however.



Rich