My car keeps jolting, or feeling as if it’s going to stall, when I accelerate. I’ve had the AA recovery people out for a different reason, and they have advised me to get new leads – but would this problem with dodgy leads be why my car is feeling like it’s going to conk out on me? Thanks.
The mechanic says...
There could be a number of reasons why your car is ‘jolting’ in the way you describe. What is happening is that the engine is misfiring, due either to an electrical malfunction or a fuel system problem. This is especially likely if the engine has not been serviced for some time. Electrical components (including the spark plugs and the high tension leads connected to them; these are major potential culprits!) do break down as time and mileage accumulates.
If you would like to make an initial assessment yourself, the first step is to remove and examine the spark plugs, and renew them if the originals look worn. If you are unsure of when they were last renewed, change them regardless for high quality replacements to the correct specification (consult your handbook for the car maker’s recommendations in this respect).
If the misfire still occurs, invest in a high quality high tension lead set.
Note that the connectors on most modern high tension lead assemblies need to be treated with the greatest of respect, especially when fitting or detaching the leads. Apply only gentle hand pressure, or the electrical continuity within the leads can be broken, with intermittent misfiring being the result of such internal breakdown.
If, having changed the plugs and the high tension leads, your engine is still misbehaving, the quickest way of establishing the exact cause of the trouble is to have the engine connected to an electronic diagnostic machine, which will ‘interrogate’ the vehicle’s Electronic Control Unit (E.C.U.). to highlight the source of the trouble. Most garages will be able to help, or a diagnostic specialist.
