Hello Everyone,

I own a 2005 Nissan 350Z 5AT Enthusiast. It currently has 100,912 Miles on it and it has been sidelined for awhile due to a misfire. When I use the code scanner, the results are P0305. which is a misfire in Cylinder 5. I have replaced the spark plugs and even replaced the coil on cylinder 5. So far nothing has improved. I tried looking for a vacuum leak but I haven't been able to find one. I have personally verified that all spark plugs and coils give out a spark so I know that isn't the problem. Looking at the Freeze Frame data, it seems that my car is running really Lean. Several people have told me that they can smell gas when the car is running. I plan to do a Dry and Wet Compression Test some time next week and I will update the post with that info. Please help because I really want to get this fixed and start driving it. I have typed the freeze frame data if that could help anyone.

Freeze Frame - P0305

Fuel System 1 Status: Closed Loop
Fuel System 2 Status: Closed Loop
Calculated LOAD Value: 32.94%
Engine Coolant Temp :174.20 F
Short Term Fuel Trim - Bank 1: 14.84%
Long Term Fuel Trim - Bank 1: 0.00%
Short Term Fuel Trim - Bank 2: 3.13%
Long Term Fuel Trim - Bank 2: 0.00%
Engine RPM: 700.00 RPM
Vehicle Speed Sensor: 0.00 MPH
Absolute Throttle Position: 4.31%

 

Short Term Fuel Trim - Bank 1: 14.84%

Yup, that's high. You might have a stuck open fuel injector. That's easy enough to diagnose.

 

Should I just replace that one injector? or how would I go about making sure that is the issue? I will post the compression test results some time Monday.

 

I had to diagnose injectors on a vehicle before. I took the rail off(with injectors attached) and had someone try to start the car and visually looked at spray. You can tell easily if one is off from the others.

 

Whatever you do, just get it done before it kills your cat. If you don't know what you're doing, get a mechanic to look at it or check YouTube. There's a ton of information already out there on how to check for a stuck injector.

Can you post a photo of the spark plug you pulled out of Cyl. 5?

 

Alright, I will post a pic of the spark plug on Cylinder 5 after I do a compression test.

 

Are you talking about the new plug? How long has it been in the car?

 

the spark plugs are somewhat new. when i first got the misfire, I replaced the spark plugs first thinking it was the solution. when it didn't fix the issue, I replaced the coil in that cylinder. I don't turn on the car often because I don't want to ruin the Cats.

 

Hello everyone,

I just got done doing a compression test to my 350Z. Its safe to say that my Piston Rings are just fine.

Compression Test
Piston 1: Dry 160 - Wet 170+ PSI
Piston 2: Dry 153 - Wet 170+ PSI
Piston 3: Dry 160 - Wet 170+ PSI
Piston 4: Dry 155 - Wet 170+ PSI
Piston 5: Dry 157 - Wet 170+ PSI
Piston 6: Dry 155 - Wet 170+ PSI
All pistons when a little bit of oil was poured inside the chamber went up to 170-180 ( AVG 175 PSI)

Freeze Frame - P0305
Fuel System 1 Status: Closed Loop
Fuel System 2 Status: Closed Loop
Calculated LOAD Value: 32.94%
Engine Coolant Temp :174.20 F
Short Term Fuel Trim - Bank 1: 14.84%
Long Term Fuel Trim - Bank 1: 0.00%
Short Term Fuel Trim - Bank 2: 3.13%
Long Term Fuel Trim - Bank 2: 0.00%
Engine RPM: 700.00 RPM
Vehicle Speed Sensor: 0.00 MPH
Absolute Throttle Position: 4.31%

my spark plugs