RPM fluctuation every few seconds with AC on at Idle in m...

Q: RPM fluctuation every few seconds with AC on at Idle in my 2013 Ford

asked by on May 10, 2017

I drive a diesel Ecosport (MT). After second service at at 6200 Miles, could witness RPM fluctuation between 750 to 960 on idle with AC on. This would happen on a warm summer day. It was happening every few seconds and caused noise and vibrations inside cabin.

Ford manual recommends an idle range of 750-800. However, they denied any issue as per them extra 180 RPM are due to AC compressor. However, I had my ETB changed by them.

At 24K miles issue is back again. Ford is denying that it is an issue. To force them or to resolve the issue I have undermentioned questions.

A. When manual recommends a RPM range of 750-800, why they saying fluctuation to 960 RPM is fine. RPM return back to 780-800 range, however, with every jerk they touch 960?

B.I notice minor loss in acceleration when I put my foot on paddle and keep it at same place.On Idle when I keep my foot on throttle to keep RPM steady at say 3000 RPM,after few seconds there is cut in power and RPM come down. engine misfiring

My car has 30000 miles.
My car has a manual transmission.

Hi there. It is common to see a small fluctuation in RPM when the AC turns off and on due to the drag on the engine. It should not drop that much though. It sounds like the idle control system is not functioning properly. Most of the time the fix is as simple as reprogramming the computer. The issue can also be caused by carbon build up within the intake of the vehicle. I usually update the computer first to see if it helps and then recommend an engine cleaning if that does not take care of it. It sounds like you need to take it back to the dealer to get them to fix it right.

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