1998 toyota sienna get misfire on No 3 spark plug.error code is P0303.

Hi,

I hope I can help with this. This could mean the engine spark plugs or plug is the issue. Also check the exhaust pipe. White smoke indicates a coolant issue. Check your coolant reservoir. Black smoke indicates a Fuel issue. Blue is an oil issue. Also, speaking of your spark plugs there very well could be a misfire.

the code P303 could be cylinder 3 misfire
P102 the mass air flow sensor which is on the air filter cover. It's an electrical part and is sensor. Please check these and let me know.

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/laura_08254539050d64db

Error Code: P0303
Description:
Cylinder 3 - Misfire Detected
Possible Cause:
Wiring harness, igniter and fuel injector connectors.
Ignition system. (Spark plugs gaps)
Fuel injector No. 3.
Fuel pressure.
Running out of fuel.
EVAP canister purge valve.
Evaporative emission system.
Low compression, cylinder No.3. (check valve clearance and throttle plate for excessive wear)
Engine control module (ECM).

Change...distributor cap ..spark plug wires or spark plugs

The 303 is a misfire, and if there's no issue with the plugs or wires, I've replace a TON of ignition coils. If you remove the coil pack and see ANY type of crack in the mold on the bottom, replace it, it's done! The 171 and 174 are typically the intake plenum seals. The plenum gasket doesn't need to be replace, but the lower seals and bolt/seal kit (the bolts that hold it on to the intake manifold) require changing.

p0303 is a mutible engine misfire on number 3 cylinder. the best fix,

A code P0303 may mean that one or more of the following has happened:

• Faulty spark plug or wire
• Faulty coil (pack)
• Faulty oxygen sensor(s)
• Faulty fuel injector
• Burned exhaust valve
• Faulty catalytic converter(s)
• Running out of fuel
• Poor compression
• but first of all check the wires and sparkplugs first!

my name is Jerry Tiet. Base on my experience on 1998 Toyota Sienna with the DTC P0303 show there is a misfire in cylinder #3. a possible cause is the ignition coil of the #3 cylinder. Compare the resistance value of the ignition coil of cylinder #3 with the other coil or simply switch ignition coil #3 with one of the other ignition coil and clear the DTC with the scan tool. Then run engine for couple days. If the check engine light on again. Let me know what is the DTC code.

The MAF sensor is not the problem, these are cylinder misfires on #1,3 and 4. replace the #4 coil pack, #1 AND 4 use the same coil, replace the spark plugs and the wires.

P0303 is misfire on cylinder#3. your car over heat?if No. check spark plug , spark plug wire, distributor rotor,and cap.

p303 is a cylinder 3 missfire I woul first check the coil and then the ingnition module, Then if this dont work you could have a bad injector. If after testing and still no fix you should check the compression in that cyl.

coils, injectors, or plugs. need more info.