Idle drop

[FestYboy]

Ok let me try this again, when the lights are not on it idles fine,(around 1100 rpm) when I turn the lights on it drops to about 550 to 600 rpm and u know that aint good, and thats supposed to be normal ????

no, that's not good, but based on your first post and description, it would be if you have a normal 700 rpm idle ("idles fine").

i'm with gocart hear and say that yoru alt is pulling too hard. also a normal idle for a festy is 650 rpm....

and just for compairison, my mom's 5.3L tahoe idles at 500...

[FestYboy]

Ypu should only require an idle up if the A/C compressor clutch is engaged or turning the steering wheel with power steering. Those two things will place a temporary drag on the belts and thus on the crankshaft. Any load on the alternator, over and above what it is rated for will result in the battery discharging to make up the shortfall. The drag on the alternator belt is constant. It should not have any affect the idle speed. Can anyone else correct me if I am wrong?

as you increase the electrical load on the alt, it will require a stronger magnetic field to maintain charging voltage. it takes more power to turn the alt through that stronger field and that will cause a load on the engine. (alt turning torque is dynamic depending on electrical load).

[stonemaster]

thanx, I'm beginning to realize a O2 swap might first be in order, when the rain quit and it dried up today, the drop was still there just not nearly as bad

[Movin]

I checked mine, less than 100 rpm difference when the idle was turned to 1050.
just for reference brakes only made less than 50 rpm at that setting.

[stonemaster]

I checked mine, less than 100 rpm difference when the idle was turned to 1050.
just for reference brakes only made less than 50 rpm at that setting.

mine is more and varies with weather conditions which means more than one issue in play

thanx guys