24v cummins high idle8/18/2023 ![]() ![]() By placing diodes in the circuit, it will let the PCM feed the servo as normal, but won't let us back feed it. Diodes only let current flow in one direction, they're the check valve of the electronics world. But there is something else that we need to remember, if we plan on having cruise control still, we must modify the system in a way that the PCM can still function correctly.įirst things first, we need to make sure be don't back feed the PCM which can cause damage, for this we'll use diodes. With our new found knowledge, it has become obvious what needs to be done. By grounding this pin, it opens the 'vacuum' valve allowing vacuum into the servo increasing the throttle. Pin 1 (tan/red) gets grounded selectively by the PCM. By ungrounding the pin, it will allow vacuum out of the servo decreasing throttle. Pin 2 (green/red) gets grounded selectively by the PCM, By grounding this pin, it closes the "vent" valve, thus allowing the servo to hold vacuum. Without power to this pin, nothing happens. Suppling this pin with power closes the "Dump" valve. This is the main feed for the system, it supplies power to all 3 solenoid valves within the servo. Pin 3 (blue/red) gets 12 volts from the PCM, through the brake switch when enabled. If the engine starts running fine again, look into getting a new injector pump.DIY High Idle using the Stock Cruise Control Servo.įirst off, before being able to modify the system for high idle, we must understand what we are working with. To test, once the engine starts to misbehave, pour a bucket of water over the injector pump to cool it down. Symtoms: Runs normal when cold, Misses and Dies once warm. ![]() For troubleshooting procedures, Go Here: Confirming Stock Timing & Checking and Reseting Timing Back To Stock Very likely issue if Injector pump was just retimed or replaced. Symtoms: White smoke, Engine Knocking, Low Power. Go Here: How to install Fuel Pressure Gaugeįuel Pressure should stay above 20 psi at all times, if it goes down to 15 psi, you know you have a problem, to diagnose the cause. It is highly recommended that you install a fuel pressure gauge to avoid blindly throwing parts at the problem. If the engine takes a couple cranks to start after sitting overnight, check for air in the fuel. Symtoms: Possible Hard Starting, Possible Misfire at idle, Possible White Smoke, Especially when engine is powering out. For more information, Go To: Fuel Shutoff Solenoid (FSS) If FSS isn’t adjusted correctly, or is full of grime, it will limit the amount of fuel the injector pump injects and thus limit power. The FSS is an electrical solenoid that lifts a lever on the injector pump. Engine runs normally, just runs out of power quick. Symtoms: Engine Low on power, No Sputtering/misfire/smoke. There are a couple things that compound the issue:īasically, If you are starting the engine on a test stand, it is perfectly normal. ![]() Same goes for when asking for much power when the engine is cold. If you start the engine, and immediately floor it, it will get to about 2000 RPM, and then pop, sputter, white smoke, and RPM won't climb. If the engine doesn’t want to start at all, go here: Engine Not Starting In this article we’ll troubleshoot low power, or the engine just not running right. 94-98 12 Valve Cummins Low Power, Sputtering, White Smoke. ![]()
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