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Experts!

Is it normal to have the rpm go below the idle rpm. I have observed in my fiesta 1.6 , after negotiating humps while the car picks up from low revs, the rpm needle touching 600 while the usual idling rpm is 800+.

I can experience low power (obviously.. it is almost as if the engine is about to shutoff) when this happens.

-tortoise

Correct me if I am wrong, isn't idling RPM usually set at +-1400?

nope it's around 800rpm when warm. around 1200-1400 when cold.

thats on bikes....most cars have their idil RPM set at 800-1100 RPM.


Rev

my RPM on cold start is about 1400 and after warming up it goes some where between 600 and 800 RPM. I never had this feeling that it may shut off while idling at 600 RPM or 600+ RPM.

Is it same for Carb type cars also? On my car, the idling increases on starting and gradually reduces. Since I dont have a tacho, cant say the RPM figure.

nope not for carb only mpfi since it's controlled by the ECU. thats why you need to give throttle while starting in the morning for a carb engine.

tortoise,

Its perfectly normal for the rpm to blip below warm-idling rpm. This is the engine directed by the ECU to a minimum rpm for fuel efficiency. The emphasis however is on the word blip.

Was just thinking if its good to keep the RPM as low as possible while driving. I mean if you car can slowly pull up in 4th gear from 1000RPM onwards is it good to do this or would we be putting too much load on the engine. Will this affect the F.E figures.

If the revvs are going lower than the idle range then check if your IAT sensor is fine .. It maybe loose at times ..

Just increase your idle rpm and that will help

1n the 1st place stock car's idle rpm shouldn't be altered for such a reason, he hasn't altered his cams or fuelling system etc...

:Frustrati
secondly, are you sure what you are talkin abt before giving such advice ?
how can you alter the RPM anyway ? are you aware of the basics of how a car engine works ?

Your answer is logically correct. But seems to be useless.
The idle RPM for carburated engines can be adjusted by turning a screw in most cases. But it not that simple in ECU controlled engines. It needs sophisticated connections and a good knowledge in ECU programming.