Idle rpm drop
 

I heard its normal if ac is on and the idle rpm drop but mine drops if i just turn the fan on for the heat. Is this normal too?

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Stock tune is often pretty unstable during idle

Im boosted and tuned so i was wondering if that could cause my idle rpm to drop with the fan on

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Does it do like that just lately?
Best would be an idle log

No its been doing that since i installed it but they said its normal just needed confirmation since its winter and i need the heat. Lol dont want my car stalling on a red light cuz of it

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manual or auto? Just blip the throttle if you feel like you're about to stall. It sounds like the problem is your tune or you have a vacuum leak. We need a log to make sure.

Manual. I wish it was my tune but sasha from on point says he doesnt see anything but ill record a log

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My stock 2013 does it as well.

When you turn the fan on with defrost settings on the AC kicks in to dry the air even though it is on a warm setting. This gives you the normal small displacement engine drop in RPM. Perfectly normal. Try turning it onto just the floor settings and a bet you get no drop.

Interesting ill try that next time

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My 2013 auto would dip every time I came to a stop, with ,or without ac on. In sport mode it was worse, since it would hold the downshift longer. If I came to a quick stop in sport, I could stall it.

@Gunman I read people saying this all the time. I have a feeling there is a fault that isn't tripping a CEL.

Also for reference, when I had an ABS CEL / limp mode, my idle would dip and nearly stall anytime I would brake to a stop.

custom tuned edelbrock, almost always a rock solid 900 rpm idle (obviously the tuner raised it). whats your "normal" idle?

floats around 900 give or take 50

custom tuned jrsc

I've noticed that it does float around a bit more when engine is warming up. Still, normal. Do clean throttle body every once in a while and it will limit dirt's effect on making the issue worse while idling.

Normal. The car idles very low when warmed up, any sudden added strain (AC, fans, and rear defroster) will slightly drop the idle. Even as the AC clutch cycles automatically or cooling fans turn on, it will drop the idle.

I had the same symptoms, AT, 2013, would dip almost to a stall when coming to a stop. I doubted the spark plugs or coil pack. A week later, symptoms of a weak battery showed up. And strangely, when I changed the battery no more dip when coming to a stop.

My manual FR-S has the same behavior when coming to a stop from highway speeds, when in neutral. But, by stall it was around 500rpm.