Throttle kicker

[JeepsAndGuns]

I would say disable it and test drive it. If there are no negative effects, then your good. If it changes things and you dont like it, change it back and just turn off the error code. Thats what I did on mine, its enabled but I have the error code turned off.

[udidwht]

With respect to the throttle kicker. It's correct name is 'Idle speed control actuator' (ISC) GM used it on some big block 454 during the TBI years. It only activated at first start (cold) and slightly cracks the throttle open. While the engine is warming up the 'Idle speed control solenoid' activates and allows vacuum to pass to the ISC pulling away from the throttle lever. At this point the IAC controls the idle speed. And of course the ISC can not be sourced anywhere that I know of. The part number for it is GM 17084953​

Here's a diagram including it: https://lt-truck-gmc.7zap.com/en/g15...623891437-0-0/

1. The real question I've had why was it included on 454 truck models but not other models?

2. If the vacuum can were to fail then what given it's not available anywhere?

[1project2many]

The "throttle kicker" referred to in the beginning of this thread is logic in the OEM calibration which opens the IAC a substantial amount when the throttle is opened. It is not the same as the physical ISC solenoid attached to the throttle body.

ISC opens the throttle when the engine is off or cold. It only reduces throttle opening when the engine is warm and running. It is a tool to allow engineers to command low idle speeds while the engine is warm without risking stuck throttle plates when the engine is cold. See here:https://www.irv2.com/forums/f22/idle...rs-608514.html

The poster of that information recommends manually opening the throttle plates slightly if the ISC becomes damaged. IME that can work.

NAPA offers the combination EGR/ISC solenoid. https://www.napaonline.com/en/p/CRB2...ressionRank=24

[udidwht]

The "throttle kicker" referred to in the beginning of this thread is logic in the OEM calibration which opens the IAC a substantial amount when the throttle is opened. It is not the same as the physical ISC solenoid attached to the throttle body.

ISC opens the throttle when the engine is off or cold. It only reduces throttle opening when the engine is warm and running. It is a tool to allow engineers to command low idle speeds while the engine is warm without risking stuck throttle plates when the engine is cold. See here:https://www.irv2.com/forums/f22/idle...rs-608514.html

The poster of that information recommends manually opening the throttle plates slightly if the ISC becomes damaged. IME that can work.

NAPA offers the combination EGR/ISC solenoid. https://www.napaonline.com/en/p/CRB2...ressionRank=24

That is the solenoid that opens and closes the vacuum to the (ISC) 'Idle speed control actuator can. Once it's activated and vacuum exists in the line the throttle plate is free to close further than when the engine is cold. Curious as to why only very few TBI setups had this and others did not? In vehicles with these devices if they are removed one will trip the MIL and get a dash SES.

[1project2many]

Curious as to why only very few TBI setups had this and others did not?

Most vehicles did not have the same underhood conditions that could cause the throttle plates to stick closed if the throttle angle is adjusted small. Surely it was an engineering fix for an unplanned condition. If you follow this link there is a nice description to help improve your knowledgebase. https://www.irv2.com/forums/f22/idle...rs-608514.html

In vehicles with these devices if they are removed one will trip the MIL and get a dash SES.

It is controlled by the pcm. The pcm has the ability to monitor voltage on the circuit. If the voltage is outside the expected window the pcm can set a code.

That is the solenoid that opens and closes the vacuum to the (ISC) 'Idle speed control actuator can. Once it's activated and vacuum exists in the line the throttle plate is free to close further than when the engine is cold.

Yes it is. I posted it so you have a source for that valve in case you want to buy one.

[udidwht]

Most vehicles did not have the same underhood conditions that could cause the throttle plates to stick closed if the throttle angle is adjusted small. Surely it was an engineering fix for an unplanned condition. If you follow this link there is a nice description to help improve your knowledgebase. https://www.irv2.com/forums/f22/idle...rs-608514.html


It is controlled by the pcm. The pcm has the ability to monitor voltage on the circuit. If the voltage is outside the expected window the pcm can set a code.


Yes it is. I posted it so you have a source for that valve in case you want to buy one.

I posted that info not long ago on iRV2 given not many are or were aware of their operation. I've replaced the sensors on this 454 (94 Southwind Storm motorhome 28ft). Thanks for the feedback. I've found it odd that outside of that vacuum can on the TBI everything for the most part can be sourced rather easily.

[Fast355]

I posted that info not long ago on iRV2 given not many are or were aware of their operation. I've replaced the sensors on this 454 (94 Southwind Storm motorhome 28ft). Thanks for the feedback. I've found it odd that outside of that vacuum can on the TBI everything for the most part can be sourced rather easily.

I had the same problem with the Idle Load Vacuum Compensator on the older Q-Jets. My 83 G20 van had one as did my 88 Cadillac Fleetwood with the 307. The diaphragm would end up failing and even nearly 20 years ago they were unobtainable except for a used part. It was similar to what you have on your TBI, except that it was sensitive to changes in manifold vacuum. When adjusted correctly it would sense falling vacuum and open the throttle slightly to compensate. It would maintain the idle speed when you turned on the a/c, turned the steering wheel, switched on heavy electrical loads or put the transmission into gear. Then when you turned off those things or put it in Park it would keep the engine idling at a stable RPM.

[1project2many]

The vacuum cans rarely failed back in the day, and the number of vehicles using them was relatively low. I had to order one after a cowboy removed his and it took a week to get one. Chances are that low demand meant less stock was needed.