I have recently done an engine swap of my corolla altis 2008 engine swap from 1ZZ to 1NZ. The overall swap is a success and there is not at all any issue other than the mileage.
-1ZZ 1800CC used to give me 168km (city) and 230km (motorway) on full CNG tank (the cylinder is large one). And surprisingly 1NZ is giving me 100 (city) and 150 (motorway) maximum. Nothing has been changed except for engine and wiring harness. The alternator and power pump is from 1NZ but the A/C compressor is same from 1ZZ.
I was expecting a mileage from 1NZ to be around 200km (City) and 280km (highway) approx but this is not even close to that of 1800cc.
The petrol mileage as well is not good.
What could be the issue?? could it be due to some sensor issue or the air blockage issue due to cng conversion or something else that is restricting such vvti not working or not connected to the ECU (may be).
Do let me know what could be the issue??? Everything else has been working fine no issues with the engine rpm dropping or anything.