Erafizz,
I have 2002 sportage with 3y-EU engine swap. Have two cylinders 55+45kg and mine is giving 200+220km in city. On patrol it is like 8 Km/L. I had problem of bad mileage and this fix worked for me.
1- I changed the custom plugs to irridium plugs NGK-BKR6EGP, I used dual point plugs as well (k20tr11) they are good for getting best performance from 3y. Both plugs work great for me, but the dual point plugs are awesome. I climb with full loaded SUV in MUREE Kashmeer very smoothly
2- Control the Air intake, I have blocked 70-80% of Air Intake hose for CNG. (Do not block air with tape or some thing, I have placed a fat plastic lid inside the air intake assebmly, do this thing very carefull coz if incase any part of the air blocker get broken and get into the engine it could harm the engine as well)
3- Try to find some leak in CNG hoses coming from CNG kit to main Air Intake Hose.
4- Check for your advancer as well, show the advancer and settings to some good electrician in your area.
5- Check for Vacuum leaks in the engine, normally for swapped engines mechanic do not close all hoses or even some gasket are weared out and they cause vacuum leak, this leak drops the pressure inside engine, even this pressure lowers than ambient pressure (atmospheric pressure) and causes the extra air to flow into the intake manifold. This causes the engine to run too rich.
6- Check your PCV valve, swapped engines normally have malfunctioning PCV valves
Do you have 4x4 working?
Hope this will help.
