Fluctuating idle RPM's with AC on.
 

I'm experiencing a sort of surge/fluctuation in the idle RPM's when the AC is on and I'm in drive or park. It's bad enough that the XF almost dies, but hasn't yet. Any suggestions?

Re: Fluctuating idle RPM's with AC on.
 

Wow, its like our cars are twins....

Took mine in this morning for the same symptoms. Idle has been at 100rpm's when the car is sitting still in drive. 2 days ago i turned on the AC and heard a bit of a growl and a bit of a surging within 100-300rpm's. Dealer ordered a new AC compressor ($1500) that my warranty covered. I still have a feeling its linked to a pulley.

Dealer said the idle seemed completely normal. We'll see if changing the AC compressor does any good but i don't think it will have anything to do with it. Guess the warranty i bought is paying itself off after all.

Ill let you know of my results around the end of the week. Hopefully someone else can chime in.

Re: Fluctuating idle RPM's with AC on.
 

Same exact problem here. What's the common denominator here?

Re: Fluctuating idle RPM's with AC on.
 

mine too!
it didnt before the eurocharge tune was put back on
and the idle is good w ac off

Re: Fluctuating idle RPM's with AC on.
 

hmmm I just put my eurocharge tune back on about 2-3 weeks ago....

Re: Fluctuating idle RPM's with AC on.
 

before everyone jumps on the "lets blame the tuner" bandwagon i have the latest tune from e/c and my car idles fine with or without the a/c on. its 95* here in tn and my a/c is never off. just my .02

Re: Fluctuating idle RPM's with AC on.
 

wasnt playing any games at all
the least of which would be blame the tuner
i was only saying thats when mine started
it runs well otherwise
and if i thought it was a problem w eurocharge i would drive right on over there tomorrow and find out
and not be here looking for answers

Re: Fluctuating idle RPM's with AC on.
 

Mine has a Eurocharged tune for a couple of years now and never any idle issues before or after the tune.
Curious to hear the outcome on this problem.

Re: Fluctuating idle RPM's with AC on.
 

I'm not pointing any fingers or insinuating anything. I'm just tired of my XF acting a fool with the AC on and need a cure. :)

Re: Fluctuating idle RPM's with AC on.
 

Re: Fluctuating idle RPM's with AC on.
 

about 3 weeks ago in houston,
where we use ac year around,
was when i had my tune restored
jerry was dynoing a new sl55 and had a v-12 or two waiting for tunes
a bentley was parked nose in near the garage door to the dyno
lambos and ferrari's kinda common at motor werks
money money money,
he was gearing up for the mile, the texas mile
and always gracious, fit me in

Re: Fluctuating idle RPM's with AC on.
 

One more observation is the idle drops very low immediately when the power windows are used.

Re: Fluctuating idle RPM's with AC on.
 

Could it be that the alternator is weak? Try moving the power seat.

Les

Re: Fluctuating idle RPM's with AC on.
 

Couldn't a faulty bearing put strain on the alternator? Turning on the AC would put extra strain causing the RPM's to drop. That could also explain the noise when turning on AC.

Am i right?

Re: Fluctuating idle RPM's with AC on.
 

Well, i've never had Eurocharged tune mine, and sometimes if i start it cold, i can here the engine idle fluctuate. just my $.02

Re: Fluctuating idle RPM's with AC on.
 

Re: Fluctuating idle RPM's with AC on.
 

I have zero air leaks.:D

First thing I did was put my homemade PVC pipe pressure tester on the T/B and pumped top end up to 17psi.

Re: Fluctuating idle RPM's with AC on.
 

I have a bearing going bad and I hear it when I turn on the air. So it's the compressor or the extra load from the compressor that stresses whichever pulley it is to rattle. I'll be pulling the belt soon and try to identify which pulley is on the way out.

Les

Re: Fluctuating idle RPM's with AC on.
 

I am new to XF. Should the throttle body be cleaned regularly? Was a popular cure-all before manufacturers began to Teflon coat them.

Re: Fluctuating idle RPM's with AC on.
 

I was once informed by a mercedes mechanic that fualty alernators were common in these motors, Mine went bad at about 8,000 miles.

Hope that info helps.