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Honda V6 Misfire Codes

5594 Views 44 Replies 7 Participants Last post by  Nail Grease
Ok, I could use a little advice.
A couple of weeks ago, my 2012 V6 Crosstour with 267k miles popped a P0304 Code, misfire cylinder 4. Checked fuel trims, Bank 2 fuel trims were way negative (lean) while Bank 1 was normal near -0+. So everything I read, figured I needed an injector. I decided to replace all the injectors while I was in there. After I replaced the injectors (Genuine Honda). It was improved, but I knew it still wasn't right. Today the scanner showed not only P0304 but P0300. Again, fuel trims for Bank 1 are normal, Bank 2 👎.
Where would you go from here.
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Maybe one or both oxygen sensors for bank 2?
Maybe one or both oxygen sensors for bank 2?
No O2 sensor code. ?
are the coils and plugs good? When was the last time the valves were adjusted?
are the coils and plugs good? When was the last time the valves were adjusted?
The engine was running smooth as silk 3 weeks ago. I have no reason to believe it needs a valve adjustment, it has been a while.
I can lift coils off each plug and the engine will faulter.
Would any of these two things cause abnormal fuel trims on Bank 2?
On a friends Camry 183k the P0300 was tentatively resolved this week with new plugs and wires
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What sensors, actuators, switches, vacuum lines and/or electrical connections are unique to bank 2?
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What sensors, actuators, switches, vacuum lines and/or electrical connections are unique to bank 2?
Definitely electrical conections to injectors for bank 2. Need to check each one.
The mosquito invasion started, shut the garage and in for the night. Had enough.
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What effect would a valve not closing all the way have on fuel trims? Looking at the freeze data, what was the coolant temp, map reading, and rpm when the code was set?
What effect would a valve not closing all the way have on fuel trims?
From what I've read, it would be a problem.
Looking at the freeze data, what was the coolant temp, map reading, and rpm when the code was set?
I dunno. Never saw the engine light come on. I drove it 65 miles at 75mph, thought I'd check fuel trims and see if it was doing any better and discovered the pending misfire codes. When parked at 730 rpms with no CEL...
ECT 191°
MAP 9
MAF .62
STFT B1 -0.8
LTFT B1 -3.1
STFT B2 -7.0
LTFT B2 -9.4
From what I've read, it would be a problem.
It is, I am asking what do you believe raw fuel leaking past a valve would show on your trims?
That data was at 730rpm?
It is, I am asking what do you believe raw fuel leaking past a valve would show on your trims?
What I've read is it would cause negative fuel trims.
I guess my doubts come because my Bank 2 fuel trims were as good or better than Bank 1 before the trouble began 3-4 weeks ago.
That data was at 730rpm?
Yes.
Not saying it is a valve, but negative trim is the result.
If your map is indicating 9 inches of vac at idle, that's very low. It should be between 15-19 generally, this is where I would start. Your b2 trims indicates a total of 16.4% fuel is being removed from b2. Focus on vac leaks there, live graph your b2 a/f sensor and start spraying your intake,hoses, injector seals. You'll see it in the graph if spray across the leak.
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Not saying it is a valve, but negative trim is the result.
If your map is indicating 9 inches of vac at idle, that's very low. It should be between 15-19 generally, this is where I would start. Your b2 trims indicates a total of 16.4% fuel is being removed from b2. Focus on vac leaks there, live graph your b2 a/f sensor and start spraying your intake,hoses, injector seals. You'll see it in the graph if spray across the leak.
Thanks for the MAP info!
Quick question,was your map data in volts as in .90v or was it inches of vac?
Quick question,was your map data in volts as in .90v or was it inches of vac?
inHG
Did some reading last night about brake booster vacuum loss. I dont recall having any problem with brake pedal tho.
Ok, just wanted to make sure I wasn't sending you down the wrong path.
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Time for some berryman chemtool b12 and some coil boots x6 (rockauto or napa - just make sure to get the ones with the springs inside). I replaced them recently and no more dreaded misfire codes.

Time for some berryman chemtool b12
Really think his brand new Honda injectors are getting plugged after a few miles?
Time for some berryman chemtool b12 and some coil boots x6 (rockauto or napa - just make sure to get the ones with the springs inside). I replaced them recently and no more dreaded misfire codes.

As mentioned, installed 6 new OEM injectors with new fuel rail O-rings.
The coils on this 268k mile vehicle came off my other Crosstour that had 103k miles. So at the most, these coils have less than 120k on them. Did a coil swap between cylinders, misfire remained on cylinder 4. Experiencing lean fuel trim on Bank 2. I'm hoping it's a vacuum leak, but I'm not ruling out a loss of compression in that cylinder. When I get the vehicle back, I'll be looking for these, and doing a compression test. Hope for the best, fear the worst.
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