Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
Scannerjohn, I agree with you that low fuel pressure would cause all plugs to be lean........but I have one concern with my arrangement. The injectors on bank1 are are in-line with the main fuel line coming into the fuel rail. The fuel rail for bank 2 branches off at a sharp 90deg "T" junction and then bends another 90deg towards to the other side of the engine. Do you think it's possible for bank 1 to have more consistent supply than bank 2? Maybe that's a stretch.....idk.
I'll certainly check gaskets tomorrow to see if we have a leak somewhere. This is a complete rebuild and I did check my work many times as I went. I've rebuilt something like 15 different engines and this would be my first gasket to leak...but hey, It could happen and I'll check.
I'll get fuel trim data tomorrow. I've checked it over the weekend and bank 1 had zero LT and basically zero ST fuel trim. Bank 2 had zero LT and something like 5%+ ST
I'm basing my opinion about your fuel delivery question on the assumption that the system is OEM. Unless their is an internal restriction, fuel pressure and volume would be equal. You replaced all the injectors so unless the flow rate of the injectors in bank 2 are different than bank 1, you should have equal fuel delivery to both banks.
The static fuel trim of +5 on bank 2 points to a lean condition but dynamic trims will tell more. Increase RPM to 1500, 2500 and 3500 and note trim values at each stage. Growing positive Better values are indicative of a vacuum leak but you have two banks to observe so let's see the results. Freeze frame info on when the P0304 sets helps as well. If you know these testing procedures, I offer them to be on the same line of thinking and understanding. Noah and Tyler are two who have invaluable insight and expertise well worth following. I look forward to reviewing your results and progress.
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
Being wrong doesn't bother me, it's being right and not understanding why that does
Last edit: 4 years 1 month ago by VegasJAK. Reason: corrected error
The static fuel trim of +5 on bank 2 points to a lean condition but dynamic trims will tell more. Increase RPM to 1500, 2500 and 3500 and note trim values at each stage. Growing positive values is indicative of a vacuum leak
I disagree with this. With a vacuum leak, fuel trims tend to improve with elevated RPM's. Growing positive values would indicate a fuel delivery, or air metering problem.
Do you think it's possible for bank 1 to have more consistent supply than bank 2?
An injector balance test would not be a bad idea.
"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer." I have learned more by being wrong, than I have by being right.
The RPM at the time of the screen shot is in the file name.
Image with file name 900 is at idle. The misfire occurs exactly when fuel trim is increased. Every once in a while the engine won't misfire for two or three seconds when at idle. 95% of the time at idle is the pattern you see in the picture.
There was no misfire from RPM 2000 to 3000.
The image with file name "3000 to 5000 to 900" is when I held steady at 3000 then did a quick throttle snap up to 5000 and then foot off the throttle back to idle. I held steady until 16:13:56 and was on and off the throttle before 16:13:57....the U shape formation. The rest of the graph is at idle with the engine trying to recover. The engine did not misfire until I gave it quick throttle snap.....and then started misfiring immediately when it went back to idle.
I tried to graph RPM on the same chart but I can't show two different Y axis and the scale is way off. I don't have any fancy dancy scanner equipment like you big dogs.....bowwow.
ALSO, I've been working through this issue for about three weeks now. Once I identified this pattern, I moved all of the coils from bank 1 up to bank 2 and vice versa. No change in performance. I then moved all of the injectors from bank 1 over to bank 2 and vice versa.........SAME PROBLEM....NO CHANGE.
Right now the only thing I can come up with is that there is some small obstruction inside the bank 2 fuel rail. I'm going to take the fuel rail off and give it a very thorough look over to see what I can see. I'll keep you posted.
I went back and re read your posts. I did not see any mention of testing, swapping or replacing 02 sensors. You gave trim values but look at the B1 and B2 sensor voltages. Graph those. What I'm thinking is the heater circuit on the B2S1 sensor is not working. When you run up the RPM the exhaust is what's heating the 02 to it's operating temp and it starts producing the correct voltages. When you go back to lower RPM the 02 goes lean.
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
Being wrong doesn't bother me, it's being right and not understanding why that does
dsorjonen, I grabbed your 900 RPM capture because you mentioned that the misfire occurs when the fuel trims increase.
I see an average of 10-20% positive increase during the miss. Shooting from the hip, that makes me wonder about an injector problem. :huh: Not a restriction, more like an electrical problem. High resistance, poor contact, like that. Probably not an injector, since you already moved those around.
"Shouldn't that set an injector code?" Well, I searched service information for this '09 Murano. There are no injector codes. In other words, the injectors are not electrically monitored by the PCM.
juergen.scholl, I can't say for certain, but it has always been my suspicion that initial startup operated in Open Loop, or there was some sort of initial enrichment table that provided enough fuel....or a combination of the two. This would make sense with what scannerjohn is suspecting regarding the O2 sensor heater circuit failure.......would you agree?
Here are some screen shots from today.I ran the engine longer than I've ever run it since the rebuild. The longer it ran, the worse it idled.....but it always clears up around 2000 rpm.All graphs are at idle. Again, everything clears up after 1500 RPM. Bank 1 and Bank 2 are basically identical after 1500 RPM.
P0051 and P0057 both bank 2 O2 heater circuit faults. With AF's the heater circuit has to be working else the 02 will not function correctly. Their heat range is over 1200 degrees F as apposed to narrow band around 600. Check the power and ground for those two 02's.
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
Being wrong doesn't bother me, it's being right and not understanding why that does
I'll check power and grounds over the weekend. I've done some of this already and I'm pretty sure I do have good power and grounds.
And if they are good, we have bad sensors......correct???
I have a busy Easter weekend so I might not reply until Monday.
And so Happy Easter everyone!!! Please remember the sacrifice Jesus made for us some 2000 years ago and celebrate the victory over death!!!!!!!!! Amen and Amen.
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In other words, the injectors are not electrically monitored by the PCM. 
