1HD-T High Idle at Cold Start (1 Viewer)

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Feb 5, 2009
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Clover, SC
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upnover.shutterfly.com
OK guys, I have installed the Grunter Extreme turbo and tuned the injection pump according to the provided instructions. The power difference is amazing! I do have one issue/question that I could use some help with....

I set the idle speed to 650 RPM after having set the fuel screw. When the engine is warm the idle now resides at 650RPM. When I start the engine when it is cool, the idle speed goes to around 950RPM. As soon as the truck warms up a little, the idle drops back to 650 RPM.

Is this normal? If not, then what do I need to do to set it correctly?

Thanks in advance for your help.
 
Its most likely the Advanced cold start device ACSD. It sits in wax and as the wax melts it goes back the the normal idle using heat from your coolant. Its an anti pollution device to help it run cleaner when its cold. I think it advances the pump timing till its warm.
You can remove it. A pic of it removed and covered with a blanking plate, 1HZ have them as standard. Any injection shop will have a dozen or so.

1599780097994.png
 
Its most likely the Advanced cold start device ACSD. It sits in wax and as the wax melts it goes back the the normal idle using heat from your coolant. Its an anti pollution device to help it run cleaner when its cold. I think it advances the pump timing till its warm.
You can remove it. A pic of it removed and covered with a blanking plate, 1HZ have them as standard. Any injection shop will have a dozen or so.

View attachment 2431918
If that is all that it is, then I am OK with it. I just never noticed it with the stock set-up. Thanks for the info!
 
If you still have the ACSD its common practice to remove it due to the internal mechanism of it possibly breaking off and damaging the injection pump.
 
X2, if your pump still has the ACSD, get it out of there before it lunches your pump.
 

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