I recently got a 2003 S40. 18 years old, yeah, I know, but one previous owner and only 74,000 Kms on it. Looks almost new and drove great to start, and had a complete vetting before I bought it. I've had it a month. Problem is, it has started to hesitate and shake when accelerating at any speed. It will shake if I rev it in park or neutral, too, so, the car does it when not moving as well. If I accelerate slowly it rarely does it, but a hard acceleration will result in a hesitation, quite strong shaking and then a lunge forward, Shaking stops as soon as I take my foot off the gas, both in motion and revving while idling. I am thinking spark plugs but I wanted to ask here before I crept off to the shop to have it looked at.

 

Any codes stored?

Could simply be worn out spark plugs - but stage 0 would be a good start.

 

what is stage 0?

 

I'll have to ask the mechanic about codes. I have no clue. ;-)

 

As new - new plugs, air filter, fluids, oil, clean throttle plate, clean pcv, timing belt if needed, etc.

 

Gotcha. Thank you. :-) I'll ask him what he did to it prior to getting it. I know the battery is brand new and it had an oil change right before I got it - (and I'd presume the air filter was done with that). I'll call him or drop by tomorrow and find out the rest.
Much appreciated.

 

Problem solved - I took it in and yes, it was the spark plugs - also an ignition coil went belly-up and the oil filler cap (aka the 710 <wink>) was cracked. By the time I got it in to him it felt like it had 4 square tires but it was all put right and it's running like it should.

Thanks for the feedback. It was reassuring and on the money.

 

Great just shows that very low km on does not mean a car is good , car standing for long time will create issues if not serviced on a time period

 

another issue common to the Gen1 S40s is cracked connectors on the wiring harness to the coil packs. Not a hard part to replace but its not cheap (as I recall it ran me $150-200 US) but for a car approaching 20 years old, it may be time.

 

Thanks for the tip!