P0305 misfire in 3.2L concorde

[scott37300]

My sister called my today because her check engine light came on. I stopped over and was able to scan it and came up with a P0305 cylinder 5 misfire. I didn’t have time to dig into anything today but will sometime this week.

Planning on pulling the coil and plug and taking a look at them and will probably do a compression test just to rule that out since I’m pulling the plug anyway. What else should I do to try and figure this out?

How do I check the injector? I’m thinking the fuel pressure is fine since it’s only one cylinder with a miss. But how do I check that the injector is working for that cylinder?

What is the best way to check for spark on a coil over engine?

Topic

[Mathieu]

I would suggest to you to replace the cylinder spark plugs. Check the connection on your spark plug wires, leaks on the cylinder 5 distributor cap, and rotor. Otherwise, check the coil packs. In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your catalytic converter needs to be replaced. It’s might also your fuel injectors.

My source : http://www.obd-codes.com/p0305

[scott37300]

Thanks. I’m going to pick up new plugs for it and replace them and then switch that coil with another one to see if the code follows it. That will eliminate plugs and will tell me if the coil is bad. My next step would be injector but not sure how to test that yet.

[college man]

use a large screw driver or mechanics stethoscope to listen for the injectors
clicking.A noid light will work to.

[EricTheCarGuy]

You might start by doing a power balance test. This can confirm that the issue is indeed with cylinder #5. Misfire codes are not all that accurate in my experience. Once you find the problem cylinder you can check spark delivery. If you have spark delivery then you can look to fuel and compression. If you eliminate compression you can then look to fuel. Also look for vacuum leaks as they can also cause misfires.

Vacuum leaks

Voltage leaks

Power Balance

Compression testing

Leak down testing

Finding TDC

[scott37300]

Thanks Eric. I ended up going over to pick the car up and the CEL was off. I cleared the codes and got new plugs. Changed the plugs and swapped cylinder 5 and 3 coils. So far so good. I did do a compression test and they were all within 175-185PSI. Guess I’ll wait and see if it throws another code or not.

[college man]

keep us posted on your progress.

[EricTheCarGuy]

That sounds like a plan. Keep us posted.

[scott37300]

Almost forgot about this! No more check engine light so hoping new plugs solved the problem. Thanks for the advice.

[Author]

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