D24TIC Confused over fast idle setting on injection pump

[Laney760]

Can somebody please explain to me what the fast idle adjustment (not the ordinary idle adjustment screw) does please? I thought the fast idle was the idle speed of the car when warm. On another thread a member says it should not be adjusted as it is set up for 5400 rpm max. I assume from this it is set up so that at max speed car is capable of it it revving at 5400 rpm, so it sets up the rpm to mph ratio? If so, why is there an adjustable setting screw for this? I read on the net that adjusting the fast idle on a car will not affect performance in any way yet also read that rpm is directly related to torque. Confused. Thank you

[Mister T]

The fast idle slide is on the injection pump and advances the timing and opens the throttle during cold starts only , do not attempt to adjust this.
If you look at the slide it has 2 water hoses attached when cold it pulls the lever forward, as the engine warms up it moves back.
If you are getting fast idle intermittantly at stops then you may need a new engine thermostat, if this slide does not work at all but starts and idles OK then leave it alone.
Mister T.

[craig8661]

to add to if you loosen the screws of the unit the cable is sprung loaded and you have all hell on getting it back in and set up all this does is increse your tickover at cold startup

[Laney760]

Thanks

I have to confess that this morning in a very tired moment I did attempt to increase my normal idle speed by adjusting this the wrong one and not the other but have put it back to where it was! I have to say the normal idle one required me to stand on my tool box using a 2 foot long Snap-on mechanic's screwdriver, large engines may have plenty of room to work around but reaching some bits are nigh on impossible!! Thanks

[Bernard333]

torque in a petrol engine roughly goes up with rpm but in a diesel it peaks at low revs and then falls off , taking it to the extreme in a series connected dc motor maximum torque is at zero rpm and drops as the revs increases , these were used on trams etc in the old days and were very effective at getting a heavy weight moving without using an enormous motor , dont know what they use now , could do with one on my V70 .