Mileage drop after cleaning Injectors

I have a five year old Maruti Alto (MPFI). I get the fuel Injectors cleaned once every year.
Everytime the injectors are cleaned the mileage drops drastically and takes about 1-2 months to get back to normal.

Why does that happen and how could it be prevented ?

does it?
I never noticed that I just use injector cleaner liquid.
May be injector is not working at full potential when not CLEANED and then it gives you more mileage and of course engine is running under its normal power.
When you clean it , it tends to become better at performance giving you less mileage.? just a thought

i agree with rahul. the injector is probably just not spraying as much as it is suppose to because its dirty. so u save some fuel but lose some performance. i would rather get that little bit of extra performance cause it would be better for ur engine to, it will run at what it was tuned to run at!!

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98 nissan 240sx turbo {summer car} 293WHP, 315WTQ at 12psi.......... goals are to reach 500whp !!
97 honda civic {winter car}
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yeah thats what i thought. lets see what dhhawal has to say

you guys r right on the money, but i think this case could be a little more complex, the metering of the fuel is controlled by the ecu and since the load of the car is the same in both the case, if the injectors are clogged, the car should feel underpowered and give a worse mileage figure because the engine will have to work harder to lift the same load...however before we get into any specifics, @naveen, from where do you get your injectors cleaned? and second of all, what the change in the mileage like; before and after?

dhhawal bhai .. too technical

I have also notice this,(Zen mpfi) got the injectors cleaned at Maruti Service Station and there was a noticeable drop in average for couple of tank fulls.
There was none to nill improvement in engine performance.

hmm, now i think thats a problem related to the ecu, i think before cleaning the injectors they probably disconnected the ecu, and its taking time to adjust to the new fuel flow rates, the only way to know for sure is getting your exhaust gases checked to see the amount of unburnt HC percentage in your exhaust..!

that is a good point but doesnt disconnecting the ECU put the car in Reset mode. Mean all the defaults

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Should the ECU take that long to adjust ? I always thought it dynamically adjusts to the quality and octane rating of fuel.