some help.

[crunkstang1214]

When my cooling fan comes on or i turn on the heat or air (not the a/c) but just the cool air my idle starts dropping between 400 to 800. it has never died, just sounds like it is going to. It will stay at 800 then go to 400 and back up to 800. But when nothing is on it idles at 800 just fine and does not drop. Could it be that alternator crapping out? thanks

 

[evil04svtcobra]

alternator would be my guess

 

[Smokin04]

If it stays @ 400 rpm when the AC clutch kicks in, then you have a problem somewhere. If it drops and then returns back to 800 you're fine. It's normal for the AC and/or fans to load the serpentine/engine like that. The computer will compensate and return the idle to normal. BUT!!! It should only be like 100-200 rpm. Put a larger main ground wire on your negative terminal. Should help a lot.

 

[03cobra#694]

If it stays @ 400 rpm when the AC clutch kicks in, then you have a problem somewhere. If it drops and then returns back to 800 you're fine. It's normal for the AC and/or fans to load the serpentine/engine like that. The computer will compensate and return the idle to normal. BUT!!! It should only be like 100-200 rpm. Put a larger main ground wire on your negative terminal. Should help a lot.

+1
When my fans kick on at idle the rpms will drop for a moment.My wide band will even do a little dance,not electrical,but swings towards the rich side.

 

[crunkstang1214]

It does it when the a/c is not on. If the cooling fan is on the idle does that the whole time the fan is on. From 800 to 400 to 800 to 400 back to 800 the whole time the cooling fan is on. But when the fan goes off it idles at 800 and never drops.