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Mopar1973Man

Mopar1973Man's High idle mod

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First off let me explain the reason for high idle functions. The 24 valve Dodge Cummins trucks tend to burn must cooler because of the extra valves in the head. But in the cool winter time temp it's possible for the combustion temperatures to fail low enough to cause tar formation on the valves and cause them to stick. This in turn will bend the pushrods cause some serious damage.
Dodge has a TSB bulletin to correct this problem by flashing the ECM and enabling the existing software for high idle.


http-~~-//www.youtube.com/watch?v=umXz_xGxank


http-~~-//www.youtube.com/watch?v=P0Ah9nK3ahc


http-~~-//www.youtube.com/watch?v=il7iJCKfmaE


Design Reasons
The reason for designing the high idle switches was to gain control over the high idle software that Cummins provided. The software works completely automatically and there is no control for the driver of the vehicle. So if the software senses that the manifold and coolant temps are cold enough it will start the proper software and start high idle. But there is several other reason people need high idle feature and need to be able to enable at temperatures above program values. Like myself I'm a volunteer with the local Fire Dept and EMS Crews so the fact my truck sits along the highway with emergency lights, hazards, head lights, etc. The alternator can't keep up so high idle is enabled. This way the exhaust temps don't fall to low and the alternator is keeping the batteries charged.

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Operation

Cold Engine Start (Coolant <140°F - Outside Temp > 32*F)


Turn on the IAT fooler and select normal high idle. Now start your engine. With in about 2 minutes the high idle should start. Once the high idle starts turn off the IAT fooler and allow the ECM to monitor the IAT temperatures. As the engine warms up to 170°F it will cancel on its own and idle normally from that point on. Cold Engine Start (Coolant <140°F - Outside Temp < 32*F)


Turn on the IAT fooler and select 3 cylinder high idle. Now start your engine. With in about 2 minutes the high idle should start once it get to 1,200 PRM's the 3 cylinder mode with begin. Once the high idle starts turn off the IAT fooler and allow the ECM to monitor the IAT temperatures. As the engine warms up to 170°F it will cancel on its own and idle normally from that point on. Warm Engine Start (Coolant 140°F-170°F)


You can start the high software with a warm engine. At this point you need to use both the ECT fooler and IAT fooler. Select the proper high idle mode for your weather conditions as in cold start procedure. Once the high idle starts turn off the IAT & ECT foolers and allow the ECM to monitor both ECT & IAT temperatures. As the engine warms up to 170°F it will cancel on its own and idle normally from that point on. Forced High Idle


Turn on both ECT fooler and IAT fooler have it set for normal high idle. Start the engine and allow the high idle to start. Once the high idle starts turn off the IAT fooler but leave the ECT fooler on. This will allow a forced high idle that never ends. To cancel it just turn off the ECT fooler and it will cancel.
WARNING: In this mode of operation the ECT sensor is completely disabled. There is no way of monitoring engine temperatures. Becareful and alert to changes in the engine at this point. If you have a exhaust brake DO NOT activate it in this mode. Enhanced Warm Up


If you have a exhaust brake you can use it will both 3 cylinder high idle and normal high idle. But be sure to turn off the ECT fooler when the high idle begins this will allow for normal cancellation. This will push the EGT temps up to about 800-850°F and warm the engine rapidly in under 10 minutes you should have 170°F of coolant temperature. Other Notes and Warnings...

  • [*]
DISCLAIMER: I'm NOT responsible for any damages to your vehicle from using this information. [*]

WARNING: Do not activate any of the IAT or ECT foolers while driving the vehicle this will have a direct impact on performance and may case serve engine damages. Alway be sure that all foolers are turned off before moving the vehicle.

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Once the high idle cycle has completed during this key cycle it is not possible to re-start high idle a second time on that key cycle. You must shut down the engine and restart to force a second high run. Now if you cancelled manually by tapping the throttle you can resume the high idle again by turning on the IAT and/or ECT foolers.

[*]

3 Cylinder high idle is going to sound rather weird like the engine is falling apart this is totally normal. This mode of operation skips or shuts down 3 cylinders from getting a injection pulse. These 3 dead cylinders produce a load on the engine and cause it to warm up rapidly.

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Even with both IAT and ECT foolers off the high idle software can start normally if the conditions require it as posted in the TSB by Dodge.

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