New help on idler problem on somewhat new car?

[Mo Power]

Ok I'm suppose to look at a vechicle tormorrow and she says when she turns it on it starts running really high like redlinin and then goes down and just goes back and forth like that. And when I heard that I assumed the distribtor or what else could be going on since I'm assuming the car is 99- and newer. Could the idle be screwed up or something but I'd figure I'd ask you guys since you know more then me  . But Those are the words she said but still running high then going down sounds weird to me.

[1969chargerrtse]

  Wow, well I would look at anything related to fuel or air first.  Meaning If I start it and I see the butterfly for the carb/ throat area is closed as it should be at idle but the thing is revving then it sounds like a vacuum leak to me.?  Air is getting in somewhere for the engine to be able to rev without moving the throttle butterfly.  It's like pulling off a vacuum line anywhere on a good running engine, it could stall but also would be prone to rev because you're allowing more air in.  I don't see how the distributor would have anything to do with it?  Even on fuel injection, allow more air, it's going to rev.  I've had this happen many times to quads and bikes, it's always a carb (fuel/air) issue when they rev up and down like that.  Kinda need to know , fuel injection, carb, throttle body?  Could be a manifold vacuum leak?  Hey I tried.

[pettyfan43]

Check for the Idle Speed Control or Idle Air Control.

Some cars have to have the Idle Speeds reset if the battery goes dead and it has to be jumped or replaced.

Those are two really good places to start.

[rt green]

what kind of car is it? what year? what engine? check engine light on?

[Mo Power]

Well she didn't tell me what car it was or anthing but I'm assuming it would be fuel injection. I guess I'll find out when I look at at 1  today. It's my bosses friend and asked me if I could look at it so I might get good with my boss  .

[Arthu®]

Check for the Idle Speed Control or Idle Air Control.

Some cars have to have the Idle Speeds reset if the battery goes dead and it has to be jumped or replaced.

Those are two really good places to start.

[Mo Power]

Well the check engine lights was on and and it would idle almost to dying point then go to 3 grand so sounds like it's a vaccum leak 69ChargerRTSE said.

[1969chargerrtse]

  Right on!  I mean, cool hope I was help.  I have no clue what these other guys are talking about so it tells me how far I've been out of the loop.   My knowledge goes back to these Charger days, I'm not up to the new stuff all that well.  Who knows could be something else anyway.  Good Luck.