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why my engine is knocking on petrol?
i have zen estilo 2007 petrol+CNG, i don't know what engine knocking is but it sounds like this 'tak-tak-tak' 2-3 per second not too loud but audible all around the cabin and car. the noise magnifies with acceleration and specially when ac is on, in mostly 3rd gear, either there is no sound in idling or it is in inaudible, however car runs well in CNG, no matter which gear or rpm-its soundless in CNG.
ok ok...i isolated the issue....when i take acceleration i.e press gas pedal too quickly when car is in gear it makes that noise however if i increase acceleration gently and slowly noise doesn't come. i can retard or stop such noise by easing gas pedal. pls explain why this happens
3 個解答
- 1wbrockstar2004Lv 67 年前
If it occurs mainly when accelerating and sounds like pinging or rattling,that's called detonation.If it is detonating,that's usually due to a defective knock sensor.The knock sensor detects detonation,signals the computer so it can retard(reduce)timing to stop the detonation.There are other causes for too but the knock sensor is most likely.Too much cylinder compression due to accumulated carbon on valves/pistons,overadvanced timing,lean air fuel mixture due to vacuum leak,overheating engine,and defective egr valve are the other causes.A worn timing chain or rod knock is sometimes mistaken as detonation.If you have an internal engine part in the lower part of the engine(shortblock)the noise will usually be audible during idle.If you remove each spark plug wire one at a time and the noise disappears or gets less audible when removing a certain plug wire,that cylinder is where the problem lies.Its usually a rod or main bearing,wrist pin,or piston slap.No noise at idle lower parts are ok
資料來源： The valvetrain area can make the noise you described.If a valvetrain part is suspect,a compression test can reveal this sometimes.For example,if the cylinders have 120lbs but one of them has 75lbs,there's a problem there.Could be a loose or broken rocker arm,broken valve spring,etc.A exhaust leak can also make a tak tak tak noise.
