Hello, I drive a 2002 model toyota vitz. The engine runs pretty smooth at times but loses power and hesitates at lower rpm sometimes. The brake also hardens along with this problem. It gets better when I shut off the engine and restart, but same cycle repeats. I have changed mass air flow sensor, oxygen sensor and spark plugs but nothing seems to have worked. Can u please tell me whats wrong? Thank you.
If the brakes hardened that's often a sign of a bad brake booster which will also affect running by causing vacuum irregularities which will mess with air fuel ratio
@scottykilmer
Thanks in advance. I will check it out and let u know if it doesn't work.
@scottykilmer
Hello again, it turns out that there's nothing wrong with the brake booster and the brake hardening thing got resolved when I replaced a leaky vacuum hose. I figured out that the problem starts when the car warms up. It runs perfect when I leave for work in the morning but, starts hesitation on low rpm and not accelerating as it should and the engine sound also changes a bit on the afternoon when I return back home. What do u think the problem is?
A intermittent wire connection or a vacuum hose that leaks, sometimes. Sometimes old stuff wears out. Vibration bounces electrical plugs. Or, vibrations move rubber push on hoses.
Go to electrical plugs and check for loose wires. Wires that are pushed into connectors will vibrate or even corrode to "make bad connections". Sometimes unplugging and re-plugging connectors will clean contacts.
Rubber hoses get hard from heat and age. Check for cracks in hoses. If at end of hose where pushed onto connections you might can trim a little from the hose and refasten for a better connection. If you can notice the loss of RPM at idle with the hood up you might spray hose connections with WD40 to see if a loss of vacuum is recovered.
Nothing is harder to find than intermittent problems. Don't let frustration kick your ass instead of the car, LOLOL!
Good Luck!
