help me ID these parts please

[HD_DUALLY]

I'm needing help with these two parts. I'm tracking down a stalling issue on my 1994 K3500 454 and ive read that a "throttle kicker" device can work in conjunction with the IAC to adjust vacuum under load and that it can be manually adjusted. I'm getting the code 36 which is "throttle kicker failure. The vacuum pod on the right is supposedly the valve but I'm not sure what the plastic sensor is called that it runs to. i know its not the MAP because I've already replaced that, along with most every other pc of electrical equipment on the truck. its either that or something do do with cruise control which my truck has but it does not work. ive searched quite a bit but there isn't a ton of info i could find. any help would be great thanks!

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[grampadirt]

The round diaphragm looking thing is the idle speed control actuator,at the other end of the tube is the idle speed control actuator solenoid.

I've had dealings with these two parts myself and drove me crazy years ago before I understood how they work.

 

[HD_DUALLY]

The round diaphragm looking thing is the idle speed control actuator,at the other end of the tube is the idle speed control actuator solenoid.

I've had dealings with these two parts myself and drove me crazy years ago before I understood how they work.

thanks that's great info! can you elaborate how they work for me as I'm still figuring them out. hopefully they are contribute to my engine stumbling problems.

 

[grampadirt]

Sure...think of the diaphragm looking thing as a high idle choke on a carb,when the engine is cold it will hold the throttle open a little keeping the idle high.When the engine reaches a certain temp(mine does it about 135*) the ecm will tell the solenoid to release(create vacuum through that small tube)the high idle,you can see the diaphragm pull the rod and the idle will drop to regular idle.On mine I can see it happening vividly,when it does it sometimes drops so quickly the engine will stall.Normally you'd be driving and never feel it happening but on a cold start and letting it run for a while you'll see the drop.So,to keep things running well be sure to keep those tubes and short hoses in good shape.One more thing...make sure the connector to the solenoid is in good shape.

One more thing,if you follow those tubes you'll see one goes to the throttle body(vacuum source) and the other goes to the actuator with the solenoid in between.

Hope this makes sense

 

[HD_DUALLY]

Sure...think of the diaphragm looking thing as a high idle choke on a carb,when the engine is cold it will hold the throttle open a little keeping the idle high.When the engine reaches a certain temp(mine does it about 135*) the ecm will tell the solenoid to release(create vacuum through that small tube)the high idle,you can see the diaphragm pull the rod and the idle will drop to regular idle.On mine I can see it happening vividly,when it does it sometimes drops so quickly the engine will stall.Normally you'd be driving and never feel it happening but on a cold start and letting it run for a while you'll see the drop.So,to keep things running well be sure to keep those tubes and short hoses in good shape.One more thing...make sure the connector to the solenoid is in good shape.

One more thing,if you follow those tubes you'll see one goes to the throttle body(vacuum source) and the other goes to the actuator with the solenoid in between.

Hope this makes sense

ok great thanks, that's kinda what i was thinking, i will inspect everything i have and go from there. i found the solenoid at a local parts store if it is bad but i haven't found the diaphragm yet. hopefully they don't actually fail that often. the problem I'm having is every time i start the truck and go from park into gear it wants to stall and die. it does it worse when its cold, once its warm this pretty well stops. all other sensors are new, new ecm, new full tune up including coil, just replaced ground straps and checked all the wiring i could find. I'm just about down to this thing and the fuel pump.

 

[HD_DUALLY]

and one more thing, if this thing regulates idle by adding or subtracting air then what does it have an IAC for? or do they just support each other somehow? and is any part of the system adjustable or it either works or it doesnt

 

[grampadirt]

Try this....unplug the tube going to the diaphragm,connect a hose(a foot long or so) and suck on a little,it should move.hold your tongue on the end of the hose to see if it will hold vacuum.If it won't you have a problem.Also the IAC has everything to do with the idle as well,when the engine is at idle the throttle plates are closed barring any air from entering the intake,the IAC is what allows air into the intake when idling.If your IAC is stuck closed your engine won't get air at idle and the engine will probably stall.

 

[grampadirt]

and one more thing, if this thing regulates idle by adding or subtracting air then what does it have an IAC for? or do they just support each other somehow? and is any part of the system adjustable or it either works or it doesnt

It merely holds the throttle plates open and raises the idle when cold and lets a little more air in.

 

[grampadirt]

It merely holds the throttle plates open and raises the idle when cold and lets a little more air in.

Basically it's a ecm controlled fast idle,much like a choke on a carb.Have you ever started a car with a carb with a choke that works?Did you ever tap the gas pedal to drop the idle down?This diaphragm is almost the same concept.

 

[grampadirt]

There is an adjustment for the diaphragm,I tried it and had no effect

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Idle Speed Control Actuator Adjustment


Procedure:

• Before adjusting ISC actuator you must first check the minimum idle speed to be within specifications. Refer to SPECIFICATIONS/IDLE SPEED. (ISC actuator must have vacuum applied so that it is not contacting the throttle lever.) See image VIEW A.
• Remove vacuum hose on ISC actuator on warm engine.
• Adjust ISC actuated idle speed to 1300 +/- 50 rpm. See image VIEW B.
• Install vacuum hose.