Hicupping in Idle

My 1999 Subaru Impreza, 2.2L Sedan has been a warrior for some years now with little or no mechanical problems.

It is currently hiccuping slightly when in idling, whether in park or waiting at a light.

I suspect I need to change the spark plugs, as I recall a similar occurrence some years ago and that did the trick.

My question to the forum is, does this symptom sound like a car that needs the plugs to be swapped? It has been several years since they were. Also any other ideas of what it might be.

Thanks everyone.

It’s been “some years” since you changed the plugs? Yeah, this could be the culprit.

When was the last time you did a tuneup?

I look over the car with my father, who is an engineer and ex-mechanic, on a regular basis. It’s never been to a dealer or other shop for work during the time I’ve owned it, which is seven years now. Granted we’ve done any number of things ourselves including the regular stuff like oil, brakes, rotors, etc.

Typically is well maintained and this “hicupping” only started in the past few days and has become more noticeable.

However I must confess I haven’t checked the plugs in a couple years, and I would estimate they were put in about 35K-45K miles ago. Maybe slightly less, but that was about when they went in which I think makes sense in terms of a plugs lifespan, no?

The problem you describe could also be caused by an improper fuel / air mixture. As an inexpensive and quick fix you may want to try a can of fuel injector cleaner. If that does not solve the problem I would then buy a can of throttle body spray cleaner and hose down the throttle body and butterfly valve.

That could be a reasonable lifespan for plugs in a higher mileage vehicle. In a newer vehicle, erosion of the electrodes as the plugs spark and the material of the electrodes (platinum or irridium) determines the lifespan of the plugs. But in a 10 year old car deposition on the electrodes from normal oil usage often causes misfiring before electrode erosion.

Remember that there are other parts to the spark rather than just the plugs. Things like an ignition wire arcing to the engine (the engine is ground) can cause misfiring.

And then there’s the possibility of a gummed up injector. If the fuel isn’t being delvered properly an engine can misfire and “hiccup”, especially at idle.

Thanks for the pointer. I think, along with new plugs, I will give this a try as I’m sure it could use a little TLC regardless.

Thanks for the help. I am definitely putting new plugs in, and will also check out the injector and give it a cleaning. Am going to scope out the wires as well.

Will report back in with my results!

I am happy to report in that after swapping out the plugs, the car is running as smooth as ever in idle and in operation.

Thanks again for the pointers.