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2001 toyota echo

2001 toyota echo. when started in AM it drives fine. when turned off and restarted , it shakes badly in idle and when driving. If you wait 12 hrs, it will run good again until restarted. but sometimes it will run fine even after being restarted several times. code P0303 came up. checked coils, injectors and plugs. mechanic said, could be PCM.

Check Engine Light Code P0303

Misfire Detection Monitor - Cylinder 3 Misfire


Possible Causes:

Fuel injectors, related wiring, sensors and computer issues
Running out of gas, or poor fuel quality
Evaporative emissions system (EVAP) concerns: fuel vapors leaking into engine
Incorrect Fuel Pressure
EGR system concerns: leaking EGR valve or restricted ports
Base engine concerns: low compression, valve train problems and timing issues
Ignition system concerns including, but not limited to:
Faulty spark plugs
Faulty coil or related wiring
Ignition module or related wiring issues
Ignition related sensor faults or wiring issues

You Don’t Say How Many Miles On This Toyota Or Whether Or Not You’ve Replaced Spark Plugs In Recent History. Put Plugs In If They’re Old And Check Engine Compression While They’re Out.

Toyota has a bulletin that suggests several remedies for poor fuel quality caused poor running engines including, but not limited to dirty fuel injectors and dirty throttle bodies. I’d try cleaning the throttle body and runnning a bottle of injector cleaner, like Chevron Techron through the gas tank. I’d consider buying Top Tier gasoline only, if you’re not already.

When it’s running poorly and it’s really dark out, stop the car and pop the hood and see if you can see any sparks jumping from plug wires / coils.

I wouldn’t put a PCM on my shopping list.


I agree wholeheartedly with CSA. A PCM at this point should NOT be on the list. A dirty fuel injector, bad spark plug, wire, or coil should be suspect long before the PCM. I’m curious how the coils, injectors and plugs were checked.

checked by goodyear . has 115,000 miles. put in new plugs, swapped coils and that did not change anything. they said they inspected the injectors. I have put in seafoam and another good brand of injector cleaner but that has not changed anything. If you listen to it, it spudders at the tailpipe and at the coil area.

Find a real mechanic.