P301 and P0304 codes I need advice
 

My little brother has a 1997 camry ce with 215000 miles on it and P301 and P0304 codes came on CEL flashes when driving and the car has no power and vibrates badly. We've replaced the spark plugs and checked the fluids. After some research I believe the issue is either bad fuel injectors or a bad ignition coil from what i have read there is an ignition coil that controls cylinder 1 and 4 this is why i'm leaning towards the ignition coils instead of the injectors I cant see how two injectors will go bad at the same time. I don't have any real mechanical knowledge just looking for some advice.

Thanks,
Phil

The odds of 2 bad injectors are slim. Still if somehow received bad gas (does happen) this can cause the engine to run poorly.

This code is for misfire in cylinders 1 and 4. According to the manual the computer recorded these misfires at different times. Suggest looking for issues with these 2 cylinders.

There is a long list of items to check for these codes.

First suggest you do an internet search on these codes and the word Camry or 5SFE to find more info.

Some issues could be: Low fuel pressure. Typically the can fuel filter seldom plugs up but if the engine has no power, lack of fuel can be one reason. The computer does not monitor for low fuel pressure, fuel pump not working correctly, etc, thus there would be no codes set.

A stuck open EGR valve would cause power issues at lower RPM's.

Issues with vacuum line leaks.

Miss-routed hoses and electrical wires.

A bad engine coolant temp sensor (ETC) for the computer can cause strange problems.

Plug wires could go bad.

Not sure how the ign system is set, one coil for each cylinder or two. If the engine has 2 coils shared by 2 cylinders, determine if cylinders 1 and 4 share the same coil.

Some people swap electrical parts around such as coils to determine if the codes change.

My guess is a fuel pressure or delivery problem, vacuum leak, coil (if common).

If you have a code reader, clear the codes and recheck when the like comes on. Determine if the codes changes as in now cylinders 2 and 3 are included. This would widen the search area.

The AutoZone website has specific car repair info in the sites vehicle repair guide section. You will need to get a password (free), but well worth it.

Ign coil secondary resistance. Place one ohm meter probe into the high voltage plug of each coil and measure the resistance.

Cold 9.7-16.7 ohm

Hot 12.4-19.6 ohm

Spark plugs cables should have no more then 25K ohms resistance.

Make sure you are using the double electrode type spark plugs.