Case study - Engine rattle at idle speed

23/03/21

Steve has finally concluded a case that he has been working on over the course of the past 18 months. A Honda Civic came in in a no-start condition after an initial failure to start when the fuel level was too low. The vehicle started after some additional fuel had been added to the tank, but the very next day it wouldn't start again and needed to be recovered to a garage. 

"Verifying the customer complaint is an essential step in the diagnostic process, but it is quite often a time-consuming task without success. On this occasion, we verified the customer’s complaint as the engine would crank but failed to start even with a sufficient fuel level displayed on the instrument panel.
 
With continual cranking at wide-open throttle, the engine would eventually start. It ran unevenly at idle speed accompanied by a rattling sound, a sulphur smell from the exhaust, and failure to free-rev beyond 2100 rpm. Getting the engine up to 2100 rpm required coaxing of the gas pedal.  The rattling sound from the engine would, however, improve above 1500 rpm.
N.B Periodically during cranking, the engine timing would appear over-advanced with momentary laboured cranking and ‘popping’ via the intake. "

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