After 13 years running the car never change or service the fuel injectors including the fuel rail system. The injectors have been clogged badly and caused misfires and lean combustions. This can be seen on the spark coloration where it is almost red which indicates more air burnt than the fuel. So cleaning the fuel injectors nozzles and check if any of them are leaking should be done.
Another small component called the fuel pressure pulsations damper (pulsation dampener) or FPD can also be faulty - and this may caused the car feeling choked or dull when accelerating. Ticking / clicking noise can be heard from the cabin when the car running on idle.
The function of the fuel pulsation damper is to absorb pressure generated by the activities of opening and closing of injectors (recoil effect). These hydraulic pulses can cause an undesirable noise which can be transmitted to the passenger compartment.
Experience of Fuel Consumptions Test:
Today 13-July-2022 an experiment after Fuel Pump, Fuel Rail (including pulsation damper), and fuel injectors have been replaced. Test drive was completed about 20 km it shows significant improvement to the overall health of the car as follows;
1. Intake Air Temperature - it used to be average around 55 to 65 degree Celsius and sometimes increase up to 80 to 90 degree Celsius. After all the replacement above the range is between 38 to 55 degree Celsius. This indicates that good fuel delivery have significant impact to the Air Intake temperature which also the same for the engine bay heat. Since the Alza car air intake pipe within the engine bay therefore temperature measured by the IAT sensor is roughly equivalent to the engine bay temperature.
2. Second improvement is steady reduction in the fuel consumptions - the car have been suffered too long from clogged fuel filter, weak fuel pressure, clogged fuel injectors, and faulty pulsation damper. It used to consumed around 12.7 Liter per 100km which is way beyond poor fuel economy sometimes it went up to 14 Liter per 100km.
3. The oxygen sensor or O2 sensor readings starting to show steady oscillations of data between 0.1v to 0.7v ~ 8v and it used to be very inconsistent.
4. The spark plugs no longer looks reddish in color which indicates nearly stoichiometric (14.7 : 1) air and fuel burnt in the combustions. It looks more white and a little black now.
The most significant lesson learnt in this test drive experiment is about fuel pressure and fuel pulsation damper (FPD). After years of investigations of what went wrong with the car with the following assumptions in mind.
- Because of the O2 sensor inconsistent data reading on the OBD2 apps - it was assumed that something wrong with it or already worn out. However this assumptions turn out to be wrong as the inconsistent data was caused by imperfect combustions due to lack of fuels.
- The second assumptions was fuel injectors gone bad or clogged - but after testing the injectors resistance around 12.5ohm to 12.9ohm seems fairly good and cleaning the injectors doesn't really changed much of anything.
- Replacing the fuel pump does increase the fuel pressure but it was not good enough as fuel still having issues not enough for good combustions.
So it turns out one last thing which is the fuel pulsation damper - it solved the issues significantly. So it is very true that the activity of opening / closing of the injectors could generate ripple effects that is repulsive in nature and that will disrupt the incoming pressure into the fuel rail. Therefore the function of the pulsation damper is to absorb that recoil effect of the fuel injectors and allow steady flow of fuel and its pressure into the fuel rail so that all the injectors have equal pressure to spray into the combustions chamber. However having that component faulty for so many years - I couldn't really figure out what was the problem until then. And now everything seems going back to where it should be.
One thing to note: If you measure the fuel pressure on the hose that leads to the fuel pump is good - that is not enough. And there is no way to measure the pressure inside the fuel rail unless you drill into the fuel rail and install pressure gauge (perodua alza 3SZ-VE engine). So to know if the pulsation damper is the problem is to check one by one if the fuel injectors and fuel pump are doing OK. If they are okay meaning only one thing left which is the fuel pulsation damper.
