Q: I have a stutter at idle

asked by on October 01, 2016

My Stratus has developed a stutter at idle. Specifically, when the ac is on. This problem started about 3 months ago and appears to be getting worse.

When the car idles without ac, it sounds good and sits between 900 and 1000 rpm. When the ac compressor kicks on, it drops to 750 rpm and stutters, shaking the car and engine and dropping the idle as low as a couple hundred. It will kill the engine completely if I dont give it gas.

The car runs great and doesnt appear to have any loss of power at speed, even if I'm at a very low speed with the ac on it does great.

Now here's the kicker: it had these symptoms for a couple months and I was told it was the ac compressor. I replaced the ac compressor properly and now have ice cold air, but the problem remains.

I have also replaced the idle air control valve, air filter, spark plugs, oil, and had the battery and alternator tested (both came back perfect).

I'm at a loss for what else it could be. Help!

My car has 169000 miles.
My car has an automatic transmission.

I would recommend checking the mass air flow sensor. As you know this also contributes to the regulation of air flow into the throttle body. If this does not have the proper voltage going to it, this may also cause a drop in rpms since the ECU detects the change in voltage as a change in air flow and will adjust fuel accordingly. I would recommend having an expert from YourMechanic come to your home to diagnose and possibly replace your mass air flow sensors.

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