Drive Accord Honda Forums banner
1 - 20 of 26 Posts

·
Registered
2011 EX-L NAV 3.5
Joined
·
17 Posts
Discussion Starter · #1 ·
Hello All,
Having issues with a 2011 accord 3.5 cold misfire on bank # 2 (cyl. 4 5 & 6) Does anyone know why my Long Term Fuel Trim on bank # 2 is -13.8 and bank # 1 is 0.0 The car is at operating temp and at idle. Checked plugs, vacuum leaks , valve adjustment, compression test.leak down test, checked timing swapped coils and all was good. Is it possible that the fuel injectors could be bad or going bad( leaking). any advise would be a blessing Thanks
 

·
Elvira
Joined
·
3,851 Posts
ALL three bank 2 cylinders are misfiring always or bank 2 ANY cylinder will misfire ?

You also need to clarify are the misfires when cold or when at operating temperatures. I'm not understanding the post as you say both. Maybe I'm reading it wrong.

After all you've checked it looks like it could be what you propose - fuel injectors on bank 2.

A bad/faulty camshaft position sensor could make a specific bank show misfires too as well as blown head gasket but you said the compression was checked.
 
  • Like
Reactions: internalaudit

·
Registered
2011 EX-L NAV 3.5
Joined
·
17 Posts
Discussion Starter · #3 ·
Sorry if it was confusing. What i get sometimes it will misfire enough on a cold start to throw a code. Which are P0300,
P0304, P0305 and P0306. When its warm it will not throw the codes but has a noticeable rough idle. All the misfires seem to be random across bank 2.
 

·
Registered
2011 EX-L NAV 3.5
Joined
·
17 Posts
Discussion Starter · #4 ·
After letting car sit for 3 days i started it and it still has a cold start mis fire on cylinders 4,5 & 6 and now throws a new code P3497. I believe it has to do with cylinder deactivation system. I replace the VVT solenoid with a OEM. While replacing i also checked the valve adjustments which were dead on. The next morning it started fine and within 2 mins it throw a misfire again and eng light is on. I'm at wits end and dont know where to turn to. Hoping someone could help steer me in the right direction and any advise would be AWESOME !!! thanks guys
 

·
Elvira
Joined
·
3,851 Posts

·
Registered
2010 Honda Accord (LX)
Joined
·
993 Posts
It usually is the oil pressure switch. I've seen this more often on the rear bank of VCM-1 engines but it can happen to the front one too, it's more or less the same thing.

If you have a good enough scan tool you can see what that oil pressure switch is reading. That should indicate whether there's a problem or not.

Garbage advice regarding disabling VCM but ETCG's video repairs a similar issue, just with the rear bank since it's on a VCM-1 engine. But the concept is the same:
 

·
Registered
2011 EX-L NAV 3.5
Joined
·
17 Posts
Discussion Starter · #7 ·

Check to make SURE this will fit your engine but the oil pressure switch for the 4,5,6 bank is probably faulty.

P3497 also points to this.

there is also this litttle tidbit 20-023 Honda Technical Service Bulletin

Is this what you changed?
That P/N that was in the TSB is the same P/N for the valve assy that I changed. The new valve assy had a new sensor on it as well.Is there any chance that the coils on the front bank (cyl. 4,5 &6)could be going bad and only mis firing at cold starts and not at operating temps. or could the ECM be bad at cold starts. Definitely mind boggling considering all the items that I checked and changed and still the same. Thanks again for all and any advise.
 

·
Registered
2011 EX-L NAV 3.5
Joined
·
17 Posts
Discussion Starter · #8 ·
It usually is the oil pressure switch. I've seen this more often on the rear bank of VCM-1 engines but it can happen to the front one too, it's more or less the same thing.

If you have a good enough scan tool you can see what that oil pressure switch is reading. That should indicate whether there's a problem or not.

Garbage advice regarding disabling VCM but ETCG's video repairs a similar issue, just with the rear bank since it's on a VCM-1 engine. But the concept is the same:
Hey Wiimaster, Do mean the oil pressure sensor down near the oil filter or on the cylinder heads.I did changed the spool valve assy and it came with a sensor attached. I'm a little over whelmed and not thinking straight so any advise from you and all would be highly appreciated. Thanks
 

·
Registered
2010 Honda Accord (LX)
Joined
·
993 Posts
That P/N that was in the TSB is the same P/N for the valve assy that I changed. The new valve assy had a new sensor on it as well.Is there any chance that the coils on the front bank (cyl. 4,5 &6)could be going bad and only mis firing at cold starts and not at operating temps. or could the ECM be bad at cold starts. Definitely mind boggling considering all the items that I checked and changed and still the same. Thanks again for all and any advise.
Hey Wiimaster, Do mean the oil pressure sensor down near the oil filter or on the cylinder heads.I did changed the spool valve assy and it came with a sensor attached. I'm a little over whelmed and not thinking straight so any advise from you and all would be highly appreciated. Thanks
Don't overthink it. Coils and ECM hardly ever fail. If the misfire doesn't move with the coil when you swap it to a working cylinder, the coil is fine.

If the spool valve assembly was OEM and it came with the sensor that should in theory be a good sensor. Best way to verify it is working is with a scan tool that can read the data from the sensor. But if you don't have that, ETCG does mention the following regarding the oil pressure switch:
A good pressure switch will read: 10.2 ohms on outer pins 11.48 ohms on the middle and left outer pin.
 
  • Like
Reactions: internalaudit

·
Registered
2011 EX-L NAV 3.5
Joined
·
17 Posts
Discussion Starter · #10 ·
well guys, Still having cold start misfires on bank 2. Car went to dealership for a software update and to check all sensors/ monitors that they can check and all seemed okay to them. The very next day cold start misfire and engine light on. I seem to be missing something but cant put my finger on it. Does anyone know if the fuel system should be in closed loop or open loop on cold starts and if possible could a bad O2 sensor cause a misfire. The car has a lot of power and seems to run fine when warm but has a rough idle when cold starts. Thanks again all.
 

·
When will the mods stop.... or will they?
2008 Honda accord Coupe 6 speed manual
Joined
·
1,515 Posts
Check upstream 02 sensor and cat converter. Bank 2 is the front of the v6 engine. You can remove the front 02 and look down and see the inside of the cat converter. If it looks mangled then it could very well be the cat. If cat looks good, swap upstream 02 sensors and see if anything changes.
 

·
Registered
Joined
·
5,171 Posts
The key is why is the fuel trim on bank 2 a -13.8%? For some reason the ECM is removing fuel from those cylinders. Some thing is adding more fuel, such as a leaking fuel injector. Or you have a clogged catalytic converter. Or possibly a bad upstream A/F (O2) sensor.



Sent from my Pixel 5 using Tapatalk
 

·
Registered
2011 EX-L NAV 3.5
Joined
·
17 Posts
Discussion Starter · #13 ·
hey Guys ,
I did replace all injectors about a week ago and had a software update. I used a scanner today and at 180deg STFT B1-11.7%, LTFTB1-0.0%, STFTB2-8.6%, LTFTB2-0.8% and now at 205deg STFTB1- 10.9%, LTFTB1-0.8%, STFTB2-3.9%, LTFTB2-0.8%. Do you think i should replace A/F O2 sensor on bank 2 or swap with bank 1. I'll definitely look into cat when sensor is removed. Thanks for advice
 

·
Registered
2011 EX-L NAV 3.5
Joined
·
17 Posts
Discussion Starter · #14 ·
I finally got a new o2 sensor and installed on Bank 2 upstream. The cat looked very good inside. Unfortunately i still get cold start mis fires on 4,5 & 6 cylinders. Fuel trims are still way off. Seems like my parts cannon is shooting blanks. Any suggestion will be greatly appreciated
 

·
Registered
2011 EX-L NAV 3.5
Joined
·
17 Posts
Discussion Starter · #15 ·
I found a vacuum leak under my inlet manifold on bank 2 side. Do you think this could cause the bank 2 misfire. I ordered new OEM gaskets to replace them away. Any advice would be helpful
Thanks
 

·
Love my VCM!!!
Joined
·
42 Posts
The key is why is the fuel trim on bank 2 a -13.8%? For some reason the ECM is removing fuel from those cylinders. Some thing is adding more fuel, such as a leaking fuel injector. Or you have a clogged catalytic converter. Or possibly a bad upstream A/F (O2) sensor.
I found a vacuum leak under my inlet manifold on bank 2 side. Do you think this could cause the bank 2 misfire. I ordered new OEM gaskets to replace them away. Any advice would be helpful
Thanks
?????????????????????????????:oops:
 

·
Elvira
Joined
·
3,851 Posts
?????????????????????????????:oops:
I agree. Those two statements are diametrically opposed. With this new vacuum leak information it makes this problem on bank2 more befuddling.

IF the vacuum leak on the intake for bank 2 was large enough, as it seems, the fuel trims would tend to be positive as it would need to add extra fuel to make up for the extra air not take fuel out. The negative FT numbers leads one to believe the bank is running RICH and subtracting fuel.

But wait..... there's more. Just reread the OP.

This is happening when the engine is "cold" start and it's running in open loop and in open loop it's not looking at the O2 so it IS running rich upon first startup. It won't go into closed loop and controlled by the O2 until the engine warms up. Open loop also won't affect the LTFT (i'm pretty confident) as you don't want to muff-up the average of the LTFT with wildly operating data from open loop data.

Leaned out intake on those cylinders can cause misfires.

Fix that leak.
 
  • Like
Reactions: internalaudit

·
Registered
2011 EX-L NAV 3.5
Joined
·
17 Posts
Discussion Starter · #18 ·
I replaced my front and back injector base gaskets and the inlet manifold gasket and all torqued to 16 ftlbs.
Car ran better on cold start but after warmer up to about 200 ECT, my STFT1 is 3.9%, LTFT1 is 0.0%, STFT2 is -5.5%, LTFT2 is 0.0%. Idles okay. Now at 196 ECT and running for about 30 mins my STFT1 is 18.0% ,LTFT1is 0.0% and STFT2 is 10.9%%, LTFT2 is 0.0%.
I sprayed carb/choke cleaner in between the upper manifold and the lower injector base the (on the front bank only) and my STFT2 dropped to -21.0% and slowly came back to 10.%.
Could injector o-rings be leaking or possible cracked manifold. Just throwing it out there.
Any advise would help. Thanks all
Will check in morning for cold start operation ...
 

·
Registered
2011 EX-L NAV 3.5
Joined
·
17 Posts
Discussion Starter · #19 ·
I replaced my front and back injector base gaskets and the inlet manifold gasket and all torqued to 16 ftlbs.
Car ran better on cold start but after warmer up to about 200 ECT, my STFT1 is 3.9%, LTFT1 is 0.0%, STFT2 is -5.5%, LTFT2 is 0.0%. Idles okay. Now at 196 ECT and running for about 30 mins my STFT1 is 18.0% ,LTFT1is 0.0% and STFT2 is 10.9%%, LTFT2 is 0.0%.
I sprayed carb/choke cleaner in between the upper manifold and the lower injector base the (on the front bank only) and my STFT2 dropped to -21.0% and slowly came back to 10.%.
Could injector o-rings be leaking or possible cracked manifold. Just throwing it out there.
Any advise would help. Thanks all
Will check in morning for cold start operation ...
well guys. the car ran for 1 days with no eng light but now i have mis fires on front bank cylinders(4,5,6).
Honda is really starting to let me down. I've tried everything I can think of and all advises given to me and still having an issue. when my engine is at 194Degrees the STFT1 is 14.1% and LTFT is 10.9% while STFT2 is 4.7% and LTFT is -0.8%. What would that be telling us . Not sure how fuel trim works .
 
1 - 20 of 26 Posts
Top