Let me try to give you a little information on the engine you have and its problem.
The engine should be an LEK802D. The block has no sleeves and the pistons are flat topped.
Now for the problem:
Blowby is caused by air entering the crankcase of the engine. All engines have some blowby. With a normal engine, on the compression stroke, a minute amount of air will leak past the piston rings and enter the crankcase. It escapes the crankcase through the vent tube. When blowby becomes excessive too much air is entering the crankcase. This excess of air can come from 2 places: past the piston rings or through a crack in the piston itself. A faulty injector will not cause excessive blowby. A faulty injector can wash down the cylinder walls damaging the rings and thus causing excessive blowby but replacing a faulty injector will not help excessive blowby.
A compression check will tell you if too much air is escaping the cylinders. A dry compression test will give you a reference point to start from. Check the compression without adding anything into the cylinders. After recording these readings squirt some oil into each cylinder and recheck the compression. If the numbers rise significantly you will know your the air is escaping past the rings and not past the valves.
If you determine the leakage is past the rings you will need to remove the cylinder head and the piston/rod assemblies. Excessive cylinder wear will usually show up as a ridge around the top of the cylinder wall. Carbon deposits can also build up in that area so be certain to gently scrape the area when checking for a ridge.
If your piston rings are intact you can also install a compression (top) ring in the cylinder bore, invert one of the pistons and push the ring down from the top of the cylinder to a point midway the stroke of the piston. Remove the piston leaving the ring in the cylinder bore, then measure the gap between the ends of the ring. This will give a combined total of the ring and cylinder wear.
If your cylinder bores have excessive wear the block will have to be removed and bored. It can be bored to accept oversized pistons and rings or bored and dry sleeved to bring the bore back to standard size.
If you decide a rebuild is in order, hold onto your wallet. Parts for these engines are expensive. Rings are around $100 per cylinder. Rod bearings are $40 per cylinder. Some parts ie crankshaft, timing cover gasket are no longer available.