Tuning is not that easy bro. Just get it properly tuned from a trained mechanic. Would only cost you 300 rupees.
And yes, You can wash your engine with water but keep a few things in mind.
1- Cover all exposed wires
2- Cover the distributor and that Air Intake.
3- Don't just pour water in terms of bucket's in your car engine. It is recommended you use some sort of spray at least. Use minimum water necessary.