Mopar1973Man's High Idle Modification
First off let me explain the reason for high idle functions. The 24 valve Dodge Cummins trucks tend to burn much cooler because of the extra valves in the head. But in the cool winter time temperatures 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 push rods 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. TSB is listed in the NavBar to the left.
6 Cylinder High Idle
3 Cylinder High Idle
Here is the schematic of the high idle fooler for 1998.5 to 2002 model year Dodge Cummins Trucks.
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.
Schematic Of High Idle Fooler Switches
Design Notes
During my setup I frequently check the status of the IAT and ECT using a ScanGauge II to verify the resistor and the value given by the resistor.
ECT Fooler resistor (3.3K Ohm) produces a signal at the ECT showing 123°F coolant temperature.
IAT Fooler High Idle resistor (39K Ohm) produces a signal at the IAT showing 28°F intake air temperature.
IAT Fooler 3 Cylinder High Idle resistor (56K ohm) produces a signal at the IAT showing 13°F intake air temperature.
Connectors can be purchased at Caspers Electronics
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Designed for the "Do It Yourself" crowd, the 103028 Connector Kit contains a gray 2-way connector used on the Air Temp Sensor, known as "AIT" or "ATS", and a mating connector. The mate is a solder-type molded connector and the pinned connector is the "Pull-To-Seat" style which means you must first push the wire thru the connector, crimp the terminal, then pull the wire back into the connector to seat the terminal. Comes with P2S female terminals. Note: Double D style crimp tool is recommended. |
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Designed for the "Do It Yourself" crowd, the 103027 Connector Kit contains a black 2-way connector used on the GM style Coolant Temp Sensor, and a mate for this connector. The mate is a solder-type molded connector and the pinned connector is the "Pull-To-Seat" style which means you must first push the wire thru the connector, crimp the terminal, then pull the wire back into the connector to seat the terminal. Comes with P2S female terminals. Note: Double D style crimp tool is recommended. |
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. Be careful 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.
 Mopar's notes |
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Some people are asking about the amount of EGT's and load placed on the engine during high idle operation on average.
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Other Notes and Warnings...
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Here is what some people thought of the idea...
http://www.cumminsforum.com/forum/98-5-02-modifications/95493-high-idle-bomb-completed.html
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| High Idle, 3 Cylinder High Idle, 6 Cylinder High Idle, ECT Sensor, IAT Sensor, TSB 18-019-01 |