My 1998 Nissan Sentra service engine soon light is flashing and idling rough what does this mean I need spark plugs and tune up?

Sounds like you have a major misfire problem. The light is flashing because the ecm has determined that the problem is severe enough to cause damage to something. If your engine light flashes it is a warning not to drive the vehicle. I'm assuming this is a four cylinder. My guess would be that only two of the cylinders are actually producing any power. I would need the following details to help you further. How many miles are on this engine? Has the necessary factory maintenance schedule been maintained? In other words have the appropriate parts been changed and serviced to keep this engine performing properly. Many things could be causing your issues. Do the necessary maintenance first, like spark plugs and whatever the manufacturer requires and see what happens. If this does not help I can help you with the rest.

is the "service engine soon" light on?? it should be on and flashing is the car is misfiring. that means spark plug or coil is not firing. if the light is on, scan it with a scanner that you can buy at walmart in automotive section. that will cost you about $60 to buy and you have it for future problems. dealer would charge you alot more to scan. or even some autoparts stores will scan it for you for free. scanner will tell you which cylinder is not firing. start there.

check the RPM booster switch which boosts up the RPM of car when AC is switched on.

Check vacuum leaks , by spraying carburator cleaner around intake manifold gasket and vacuum hoses connections . See if engine picks up the idle speed while you doing it , and if it does , locate leak and fix it. Most common , intake manifold gasket brakes.

Hi shoemaker.
Fuel filter issues show up in high demand fuel needs such as passing or going up hills. Rarely do they cause rough idle problems.
Is the check engine light on or flashing? A flashing light indicates engine misfire and should be repaired as soon as possible.
So you could have a vacuum leak, a stuck EGR valve, bad ignition coil, worn spark plug, and many other items.
If you don't have a check engine light and haven't done a tune up do one to eliminate a few items and see if that smooths it out.
If you have further questions ask me and I will check and answer you.

KL

check distributor unit, cap and rotor and throttle idle sensor, only problems is you can test the sensor, take it to auto zone and have them plug in the computer and see if any code and wont cause you anything the code will narrow it down.

Don't think it's major could be any number of sensors. Any autozone will run a free scan and point you in the right direction.

I had the same problem. It was the intake gasket, very common in this model. A $12.00 gasket - Nissan wanted $1000.00 to install it. I got it done for $327.00 - engine light still remains on but car drives just fine.

buy yourself a scanner [ebay] only cheap & learn to do it yourself with its manual it comes with alist of error codes & their meaning
costs less than the last time!

a rough idle/high idle is indicative of a malfunctioning TPS(throttle position sensor) this is located on the throttle body ,is attached with (2) screws/bolts to the throttle body housing right off the butterfly shaft. it has either 2 wire or 4 wire plug. the replacement part can be purchased at locale auto parts store. I would also agree that a full service and tuneup be done. this will help with performance and will increase the fuel efficiency. please rate this...thanks