Vitz 1KR-FE engine problems

[muhammedsalarkhan]

Might be an unpopular opinion, but I recently had a really bad issue with vibration and fuel economy to the point where the engine would goto really low RPMs and stall.

The issue was narrowed down to a faulty VVTI cam gear. 1KR-FE has a VVTI gear driven by oil pressure on the intake cam. When I got that replaced the engine response is really good it doesn't vibrate crazy anymore and my economy went from 9.5 within city to 11.7, and on long routes its giving me 18 km/l

This experience has taught me that the VVTI gear is very crucial for a good fuel economy.

[pwuser152959674118]

Hello,
I have 2013 Vitz, 1KR-FE.
My car jerks when I press gas pedal moderately, and jerks happen till the speed of 50-60 km. After that it runs fine.

After purchasing it, I change transmission oil CVTF-FE 4L tin box, also changed oil filter.
The oil pressure calibration is also done.
I have checked the fuel pump, and it provides a sound pressure of around 80-90; the old one was at 35.
The plugs are changed. Ignition coils are in good condition, and there is no leakage of current.
Injectors are changed, and no error appears after checking ECU.
The average is good in city around 13, Engine runs smooth and fast on high throttle, but the only issue is jerks.
What else should be done?

[pwuser152959674118]

I checked the coils, fuel filter, pump, plugs, throttle body, MAF sensor, cleared manifold, and EGR, and the issue persists.
I observed that when I drive on an incline on a road, it jerks, but when I drive on a decline, it does not jerk. Also, when pressing the gas, the car revs more, but the speed does not go as fast as it should.

I purchased Techstream and mini VCI; there is no error appearing in the system. Live data is also good.