Cultus efi 2007 rpm fluctuation

[pwuser154070345481]

My cultus efi 2007 has developed the problem of rpm fluctuation. Even when I leave acceleration the rpm point doesn't get down till I change the gear. After the drive its rpm keep fluctuating at 1000 and around at idle mode. Mechanic told me that its engine head needs mild work worth Rs 5k and another suggested to get the rpm bush near the carburetor replaced. It's common problem in in this model. Plz suggest me its proper solution so that I may proceed accordingly without having my car damaged.

Thanks

[Mirza967]

Ur iac valve is at fault...,..when ur car is fluctuating rpm......keep listening to exhaust note.........if it's doing bhuk bhuk type of noise from exhaust at idle....then it's head valve issue........if it's doing missing on giving sudden acceleration then it's ignition related issue

[pwuser154070345481]

At first it did missing during sudden acceleration but was repaired by mechanic who replaced its fuel filter which was drastically dirty. He also tuned its engine. After it the problem of rpm fluctuation has hit. I am quite new and don't have any idea about the iac valve or the technical terms. Well, thanks a lot bro. Is it fine at 1000 rpm at dle?

[Mirza967]

Thousand at cold start and 850_900 at fully warmed up

[pwuser154070345481]

It goes 1500 at cold start and reduces upto 850 and 1000.

[Mirza967]

Hmm this is ok
.......but fluctuation is bit on high side

[noble313pak169]

Change air filter 2ndly spray good carb cleaner in throttle and reset computer

[pwuser154070345481]

One cylinder of the engine was not working properly which was set by the mechanic. Replaced the gas kit. Engine runs very smooth and noiseless. Now there is no rpm fluctuation but the car knocks at the first gear. What can the real problem?? The rpm also goes down the 800 sometimes but soon recovers.