I built a mpg/high idle for my truck a month or so back and I am having a problem and hope that I can get some insight. When I turn on the high idle I get a temp reading on my Scangage 2 of 137 water temp and 31 iat temp. If and when it starts the high idle as soon as it hits 1200RPM it goes to 3 cylinder. I have a 3 cylinder switch that will make the iat read 13 degrees but it makes no difference. This has worked this way except once when the outside temp was below 32 degrees. I tried to have a dodge dealer check this and they said that I have a 12v ( manufacture date is Feb 1998 ). I know that it has been flashed for the high idle buy the PO but he didn't know that it had been working incorrectly. What the big question is if I just needs the high idle reflashed or a complete reprogramming and what I can do about dodge thinking that it has a 12v in it After 3 weeks and 5k miles I can tell that the mpg setting is working and am satisfied with it.

You might want to check with Ed Grafton (Yankneck). He is the mastermind behind the high idle/mpg fooler. You might just give him call, he should be able to walk you through any issue there is.

 

This might be a funny question, but are you positive that it is a 24 valve? 1998 was the changeover period as I am sure you probably know. The reason I am asking is I dont see a signature. What are some details about your truck? Year, model, engine, transmission, etc.

First off select the mode you want BEFORE starting. Then start the truck. Leave the switch set don't change till your ready to roll then select either MPG or OFF. That should resolve your issue. The problem is most people turn the knob too slow it breaks the circuit to the IAT just long enough to show a super low temperature and POOF 3 cylinder mode is set. To cancel this mess shut off the ignition wait 15 seconds of so and high idle is completely cancelled. Yes. that's the only way to cancel the mode.
 

 

You might want to check with Ed Grafton (Yankneck). He is the mastermind behind the high idle/mpg fooler

 

Actually I was the creator of the high idle but Ed Grafton (Yankneck696) redesigned the unit to current setup.

 

Ed Grafton is working on a updated design of the high idle kit now.

 

Yes I am sure it is a 24v-motor has it on the valve cover-label on doors-has a vp44 IP. I went out this morning and set the high idle then started it, waited 6 min. and no high idle (45 degrees outside). Shut down engine and restarted after 5 min with switch off then turned on high idle and waited, after 10 min no luck. I don't question the unit as per my scangage2 all parameters are correct. I will be out of town later today and will try a different dealer to see if they know what is going on. Sadly the last dealers cummins tech had never heard of the high idle/3 cyl. and he said that he owns a 2000 with a cummins in it and he lives and works in WI.

Know anyone with a smarty? They can flash you. Post your location and see if anyone is local.

If the previous dealer told you that you have a 12 valve.... RUN LIKE HELL!!!!! They have absolutely no idea what they are doing. I question the flash the previous owner did. Maybe you can find someone with a Smarty and re-flash the high idle?

If someone nearby has a smarty that would be ideal.  Otherwise call around to other dealers and give them the TSB number.  I went through this.  The 2nd dealer I called knew what it was without looking it up.  I confirmed the TSB number with him and set an appointment.  Cost $65, but the tech also programmed a key fob since I did not have a working one to program off of.  So it may have been a little cheaper with out that, but it should be close.  Here is the TSB. http://articles.mopar1973man.com/2nd-generation-24v-dodge-cummins/29-tsb-technical-service-bulletins/85-tsb-18-019-01-cold-idle-engine-warming  If you go the dealer route and want the 3 cylinder after the update they must go back in and turn it on. 

First off select the mode you want BEFORE starting. Then start the truck. Leave the switch set don't change till your ready to roll then select either MPG or OFF. That should resolve your issue. The problem is most people turn the knob too slow it breaks the circuit to the IAT just long enough to show a super low temperature and POOF 3 cylinder mode is set. To cancel this mess shut off the ignition wait 15 seconds of so and high idle is completely cancelled. Yes. that's the only way to cancel the mode.

 

 

Actually I was the creator of the high idle but Ed Grafton (Yankneck696) redesigned the unit to current setup.

 

Ed Grafton is working on a updated design of the high idle kit now.

 

I knew that you are the original designer. I meant in no way to take that from you, I just referred the OP to Ed just because of the fact that he has been building them. Whenever I had an issue I was told to call him. Meant no harm

All good... Not meant to attack you either...

I know that the high idle has been enabled because it does work . I do think that MOPAR1973MAN has it right in that I think that it is seeing a momentary open thinking that that was a colder temp and starting 3 cyl. mode. I hate to say it but I could not find a place that I liked for MOPAR1973MANs unit so I built one of my own. I will be redesigning  the IAT circuit to eliminate the possibility of it seeing a open this winter but I don't have a garage is it wont get installed until next spring. I have been to two dealers and they don't know anything about 2nd gen 24v or earlier , all young guys that were only taught CRs.