Engine Performance problem
1999 Nissan Primera 4 cyl Two Wheel Drive Manual 55000 miles
I think I may have a problem with my engine management system, and I feel it may be related to ther idle speed sensor on the crankshaft. I had a diagnostic performed. The mechanic stated the diagnostic highlighted a fault with the crankshaft sensor, but this only needed resetting as no problems were labelled. The engine light was on, after the reset it was off, fair enough. A few hours later it was back on. Now: the symptoms. The engine is not revving steadily, either on tick over or at any other speeds, resulting in the revs fluctuating consistently up and down by 5, so basically regardless of the revs, it will fluctuate + 5 and back to where it should be every second of every mile. If the crankshaft sensor was at fault, and upon resetting has now flagged up the same fault, undiagnosed by the garage (who is a reputable one) then what underlying issues may be at fault that do not appear on the electric diagnostic? I'm stuck and fed up. Please heeelllpppppppp.