1998 Toyota Camry Misfire

Engine Miss Fire and Rough Running Condition

There are three kinds of gasoline engine misfire scenarios, first there is the "under load" misfire and there is the "at engine idle" misfire, and finally there is misfire continuously. All engine misfires exist because one of three things has occurred. First, a cylinder has lost compression, a cylinder needs a certain amount of compression to operate correctly. Second, the ignition system has failed or is failing intermittently, spark is needed at the time of compression to ignite the fuel air mixture. Third, the fuel air mixture is incorrect, proper mixture is needed for the ignition system to ignite fuel properly. If any of these conditions occur in the engine, the engine will misfire.

1. Low or no compression can be caused by

a. burned or leaking intake or exhaust valves
b. worn or broken piston or piston rings
c. worn out camshaft
d. wrong weight motor oil was installed holding the cam followers from adjusting
e. broken valve spring
f. failed head gasket.

2. Ignition system has failed or is failing

a. spark plug has fouled or is worn out
b. ignition coil has failed
c. spark plug wires have shorted
e. engine control module coil driver has failed

3. Fuel/Air Mixture is incorrect

a. vacuum leak at the intake manifold
b. fuel injector has failed
c. EGR valve is stuck open
d. mass air flow sensor has failed
e. oxygen sensor has failed
f. air intake boot is cracked

Most vehicles can monitor the cylinder misfire condition and will illuminate the "service engine soon" light if a cylinder misfire has been detected. A engine code reader is used to read the trouble codes and can isolate the cylinder malfunction. See Checking Trouble Codes after the repair is complete the "service engine soon" light must be reset with a code reader. The vehicle has to be driven thoroughly (30 to 60 miles) to let all computer monitors and relearn their system to deem the vehicle repaired.

common problems:

1. fuel injector has failed or is failing

2. spark plug wire has shorted

3. spark plug is worn out or is cracked

4. ignition coil has failed is failing

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If you have 2 bad injectors it would.

Have you check the plug wires? If they are original I would replace them.

Before you replace the EGR take it off and clean the carbon out of it the best you can.