Vibrations at idle on M13AA Jimny

Hi all,

it's been few months now since my Jimny randomly vibrates (misfires kind of). Also in some situations it is felt when driving.

Upon diagnose, I've found that O2 sensor is not reading correct data therefore I've replaced it with improvement but ocasional vibration is still present. Sparkplugs changed, no improvement.
No errors on ECU, no oil or gas smoke nor abnormal petrol smell...

I understand that crankshaft and or cam shaft sensor could generate this behavior - any methods to check these or replacement is the only solution?

 

Other than the above it may also be the coils and plug leads that can cause intermittent misfire. Also cam and or crankshaft tend to be heat cycle related and cooling off with water may temporarily rectify.

Thanks Lambert

Misfire (fuel with no spark) would be detected by the ECU.
Crankshaft/camshaft sensor generate input signals for injection and ingnition coil, therefore no injection followed by no spark would not not generate a misfire (nothing to burn).

I guess that the only way to find the solution is to start to replace sensors...

Misfire is usually detected by the ECU looking at the crank/cam sensor and it expects to see a small kick at every cylinder firing. If you have a misfire you don't get a kick and the sensor is calibrated so it knows the position of the kick and hence which cylinder misfired.

A misfire fault will only be recorded in the ECU if you get a few (2, 3 or more) misfires from the same cylinder, so if you just get one misfire and then again some time later, you might feel it but no error code will be recorded.

There a lot of things which can cause a misfire, it is usually a case of going through them one by one. Of course if you are lucky enough to get a fault recorded, especially if it is always on the same cylinder then that is a good starting point.