2008 SMAT CAR ENGINE MISFIRE

I'm assuming you mean codes P0300 and P0301. Black soot on the plugs is usually because the fuel system is running 'rich'. This is when the fuel/air mixture going into the engine has too much fuel in it. Changing the spark plugs was a good step to take but it won't fix the problem.
When was the vehicle last given a full service? Something as simple as an old, dirty air filter can cause problems.
If you are not familiar with working on engines take the vehicle to a good mechanic and get them to look at it for you.

when last you service the engine,check your spark plugs and if it not running on all look at the set its not running on and check and see if any wet with gas if they are or if they black change them

called misfire.
that means its not holding closed loop status at idle
ever do a tune up on it?
old spark plugs dont work, they MISFIRE and idle fails.
all cars for 100 years ,same , gas engines.

it can also be, bad fueling. or a bad engine.
we check compression first
then spark then fueling;
in that order, engine can not run right out of that order.
so misfire.
too rich misfire.
or too lean.
we check that by gazing at the spark plug tips ,
black is rich, white is lean.
most cars are cream or very light tan color. normal.
learn to read the spark plug tips.

its and 2000, and the scan tool will show the car is not i closed loop
at idle, fix that first. and DTC errors like MISFIRE P0300 or bad idle.
the same scan too show LTFT, long term fuel trim.
if its way far from 0 , the fueling is wrong.
-3-5% is normal. -50 is stuck rich and misfiring.

find reason for rich condition.
any shop can do that.
this takes tools and know how.
DIY? is engine running rough, and spark plugs, black?
that is rich misfire. find and ASE certified technician at a shop to do
this basic diagnosis.

Test all injector. Must be with in specification. If not replace it.


Mai Lor

when the light flashes there is a misfire taking place check the plugs and spark plug wells look for black lines down the sides of the plugs

It might be your coolant temp. sensor-not the sender for your dash gauge, but the sensor that tells the computer the engine temp. I'd also replace the spark plugs. If they have a sooty, black coating your engine is running rich. Does the engine light still come on? If same code, you need to check that circuit out more fully.

Change your oxygen sensors - they're responsible for feedback that the computer uses to determine the air/fuel mixture. They usually are good for about 60k miles and then start to go downhill. When they get to a point that the computer won't trust them, it ignores them and runs on preprogrammed fuel maps that run excessively rich (too much fuel) to safeguard the engine. You've probably seen a decrease in fuel mileage as well. And the O2 sensors have to be up around 900 degrees before they'll work - the car ignores them until then. That's why you run fine after a cold start but run rough once the car is warmed up.

The O2 sensors you want to change are in the exhaust system between the engine and catalytic converters (the "pre-cat" sensors). There are O2 sensors after the cats as well, but those are used comparatively to determine how well the cats are functioning. The primaries are the ones used for fuel mixture. If it's been this way for a few weeks or so, I'd put new spark plugs in as well - rich fuel conditions can foul them and contribute to the rough running.

usually when it gets colder outside the car will misfire and run rough because the ignition module/coil pack goes bad and makes it misfire,youre gonna have to replace the coil and module,,its the black long piece that sits on top of the spark plugs,1 wire connector and 4 10mm bolts remove them and pull up hard to pop the plug boots off the spark plugs,then install the new parts and you should be ok

have an 02 misfiring on no7 cyl was catalytic converter