[insanesam]

Hi

I have trawled through the forum and have found no concrete solutions.
Recently my car has experienced Bank 2 misfires for cylinders 4-6 (codes are 29D0,29D1,29D2,29CC) and o2 sensor codes 2C3e and 2cab only on a cold start. Runs absolutely fine once warm. The cold starts are very sporadic, it can come 3 consecutive days, then it can be fine for 15 days, then back again. Hence it is not really reproducible. Car is completely stock and has 90k miles

Bank 2 injectors (index 12) about 5k miles old with the plugs/coils 5k miles old for all 6 cylinders. o2 sensor too is about 5k miles. Bank 1 injectors are original.

What I've done so far
- replaced the valve cover gasket since there was minor oil leaks into the spark plug tubes. I've confirmed there have been no leaks since
- replaced all spark plugs again with Bosch oem
- replaced Bank 2 (4-6) injectors again with index 12 and coded with INPA although there was no smell of gas and sparks were not wet
- replaced o2 sensor since there were o2 sensor codes (bosch 17098)
- reset adaptations with inpa
- all vacuum lines recently replaced (about 2k miles) with 4mm silicone


Car started fine and drove fine for the day. However yesterday morning the misfire came back for Bank 2, but this time no o2 sensor code. This morning car was fine. I'm waiting for the car to misfire again so i can log it. In the meantime below are some logs of my normal driving and this morning's cold start (with no misfires). Hopefully someone can pick up on any anomalies

Here is a log of my normal driving
https://datazap.me/u/peanuts/log-151...normal-driving

Cold start log
https://datazap.me/u/peanuts/cold-start

Any advice/suggestions greatly appreciated.

[RocketSurgeon]

When the injectors were replaced, did the injectors have decoupling elements installed along with fresh seals?

[insanesam]

Originally Posted by RocketSurgeon

When the injectors were replaced, did the injectors have decoupling elements installed along with fresh seals?

Yes they were brand new index 12 injectors from FCP Euro (with seals) and i ordered new decouplers aswell.

I was logging my drive home today and i noticed at one point car was decelerating and Bank 1 AFR went up to 234.xx and Bank 2 went to 28 and was just stuck there for the rest of my trip home. When i restarted the car the AFR for Bank 2 was back for ~14.7.
Also O2 sensor codes are back 2c2e (Coasting mode check), 2c3e, 2cab

Any ideas?

Here's the logs
https://datazap.me/u/peanuts/afr-ban...12-13-16-19-20

[badblackcoupe]

what year is the vehicle? think it could be injector MOSFETs?

[insanesam]

Originally Posted by badblackcoupe

what year is the vehicle? think it could be injector MOSFETs?

2008
how would i determine its the MOSFETS?
And why would restarting the car make it go back to normal

[HawkeyeGeoff]

Originally Posted by insanesam

2008
how would i determine its the MOSFETS?
And why would restarting the car make it go back to normal

It depends on the symptoms but many times vehicles will run a diagnostic check right on start up...warm up cycles for O2 sensors, etc.

If none of that works, consider swapping the MOSFETS out. Lots of problems with those from the earlier ECU's (MSD80...check to see if you have that as well). http://www.n54tech.com/forums/showthread.php?t=38698

How to check to see if they're bad:

*edit* Sorry I didn't fully read that you had basically done my suggestion. Post edited to remove fluff. Inspect ECU and change MOSFETS.

[335e92tx]

does it make any difference if it doesnt sit for more than say 4 hrs?

I had a cyl 4 misfire on coldstart the other day.. only once..

I think I got one inj thats a little leaky.. at times on warm start it can be a little rough..
And bank2 O2 also is a a little slow coming back to full lean at lift throttle..

g/l...

[insanesam]

Originally Posted by 335e92tx

does it make any difference if it doesnt sit for more than say 4 hrs?

I had a cyl 4 misfire on coldstart the other day.. only once..

I think I got one inj thats a little leaky.. at times on warm start it can be a little rough..
And bank2 O2 also is a a little slow coming back to full lean at lift throttle..

g/l...

The cold start misfires have been very sporadic. I would get cylidners 4,5,6 misfire on one day. Then the next 15 days would be fine. Then misfire back on same cylinders. More recently it has been fine for the past 3 days

[insanesam]

Originally Posted by HawkeyeGeoff

It depends on the symptoms but many times vehicles will run a diagnostic check right on start up...warm up cycles for O2 sensors, etc.

If none of that works, consider swapping the MOSFETS out. Lots of problems with those from the earlier ECU's (MSD80...check to see if you have that as well). http://www.n54tech.com/forums/showthread.php?t=38698

How to check to see if they're bad:

*edit* Sorry I didn't fully read that you had basically done my suggestion. Post edited to remove fluff. Inspect ECU and change MOSFETS.

Based on post #2 on http://www.e90post.com/forums/showthread.php?t=229483 I used realoem to lookup the dme and it seems to be MSD81

[HawkeyeGeoff]

Originally Posted by insanesam

Based on post #2 on http://www.e90post.com/forums/showthread.php?t=229483 I used realoem to lookup the dme and it seems to be MSD81

You cannot trust that; it uses the latest PN's. When these go bad, the dealer will not service them and just update them to the latest PN.

Go yank off your ecu cover and actually look at the numbers on the ECU.

[Nexus313]

Hey man. I dealt with your issues before. Except mine was bank1. Here's the resolution to your problems:

Bank 2 Pre Cat O2 Sensor is bad (Only replace with oem Bosch) OR
If you have an MSD80 DME on your car there's a chance your mofsets are fried. In that case, PM me and I'll hook you up with a guy who will help you fix your problem. If your DME is MSD81 its VERY unlikely that mofsets failed.

I'd say try replacing the bank 2 precat o2 before you jump to the dme problem. And if the problem exists after bank 2 o2 sensor replacement make sure you do a continuity test from bank 2 o2 sensor port to the dme to ensure your wiring harness is fine, otherwise a new DME is useless if the continuity is bad.

Good luck!

PS; it's very unlikely that all of your injectors in bank 2 failed at once. So don't throw money at that just yet.

Edit: since you said you already did bank 2 o2.. there could be a chance it wasn't installed properly or damaged in installation (they're sensitive) where did you buy your o2 from? Make sure they are OEM (I recommend fcp euro).. I had to change mine twice before it finally fixed the problem.

[insanesam]

Originally Posted by Nexus313

Hey man. I dealt with your issues before. Except mine was bank1. Here's the resolution to your problems:

Bank 2 Pre Cat O2 Sensor is bad (Only replace with oem Bosch) OR
If you have an MSD80 DME on your car there's a chance your mofsets are fried. In that case, PM me and I'll hook you up with a guy who will help you fix your problem. If your DME is MSD81 its VERY unlikely that mofsets failed.

I'd say try replacing the bank 2 precat o2 before you jump to the dme problem. And if the problem exists after bank 2 o2 sensor replacement make sure you do a continuity test from bank 2 o2 sensor port to the dme to ensure your wiring harness is fine, otherwise a new DME is useless if the continuity is bad.

Good luck!

PS; it's very unlikely that all of your injectors in bank 2 failed at once. So don't throw money at that just yet.

Edit: since you said you already did bank 2 o2.. there could be a chance it wasn't installed properly or damaged in installation (they're sensitive) where did you buy your o2 from? Make sure they are OEM (I recommend fcp euro).. I had to change mine twice before it finally fixed the problem.

Thanks for your input.
My production year is 10/2008 so I'm pretty sure it is MSD81.
The previous o2 had about 10k on them which I now believe were not the issue. However i replaced them anyway and I was extremely careful to not bang it around or twist the wires. I am using the Bosch 17098 sensor from FCP.

[Nexus313]

Originally Posted by insanesam

Thanks for your input.
My production year is 10/2008 so I'm pretty sure it is MSD81.
The previous o2 had about 10k on them which I now believe were not the issue. However i replaced them anyway and I was extremely careful to not bang it around or twist the wires. I am using the Bosch 17098 sensor from FCP.

That's very odd that you're still getting misfires in bank 2 then.. Get a smoke test done and check for leaks.. Un-metered air could be entering the system. Make sure your engine covers off. Also you could try cleaning the intake valves by getting a walnut blast done.

Lastly, check the PSI on HPFP/LPFP to see whether or not they are failing.

[insanesam]

Originally Posted by Nexus313

That's very odd that you're still getting misfires in bank 2 then.. Get a smoke test done and check for leaks.. Un-metered air could be entering the system. Make sure your engine covers off. Also you could try cleaning the intake valves by getting a walnut blast done.

Lastly, check the PSI on HPFP/LPFP to see whether or not they are failing.

Smoke test done and cannot find any leaks. I noticed my LTFT at idle for Bank 1 is about 16% and Bank 2 0 % (but bank 2 is the actual issue). So i assumed its an intake leak and replaced the intake manifold gaskets and throttle body gasket. I'll just wait and see now.

The valves were cleaned 10k ago, but yes another clean would not hurt but I doubt this would be the issue.

I've read various random forums that replacing the low pressure fuel sensor has resolved some similar issues with no clear explanation though.

[insanesam]

I was driving at lunch time today (the car is already warm) and the AFR for bank 2 got stuck at 28 again. This happened on deceleration, which is what happened last time.
As previously mentioned the LTFT for Bank 1 is about 17% at idle and 0-3% for Bank 2 (which has new injectors and o2). Again the stuck fuel trim is on Bank 2. if anything it looks as though Bank 1 is more likely to max out.

I took a log and was unscientifically analysing them and I noticed just before the AFR for Bank 2 got stuck, the low pressure fuel sensor was reading 85 PSI. in both instances. Also back to getting o2 sensor codes 2c3e, 2cab and 2c2e "Coasting Mode Check".

New log here
https://datazap.me/u/peanuts/bank-2-...3-7-8-12-18-21

[Nexus313]

I've read about the LPFP sensor too. When I had this issue with bank 1, I actually went and bought both hpfp sensor and lpfp sensor and still have them and never ended up using them.

[insanesam]

Originally Posted by Nexus313

I've read about the LPFP sensor too. When I had this issue with bank 1, I actually went and bought both hpfp sensor and lpfp sensor and still have them and never ended up using them.

How did you end up resolving the issue?

[Nexus313]

Originally Posted by insanesam

How did you end up resolving the issue?

For me this was my problem: I was getting bank 1 misfires, so I replaced the O2 Sensor with a sensor I got off eBay along with all 6 injectors, coils and plugs. It turns out that sensor was not OEM bosch and was a cheap aftermarket one from china. It ran okay for a few weeks until the sensor messed up again and I got bank 1 misfires. So I replaced with a bosch oem from fcpeuro and did a full adaption reset of the values via ISTA/RHEINGOLD (I think this step is somewhat important after changing the sensor, and can be done via INPA too.) .. after that I got 29F4/29F5 code which is for cat efficiency every 500kms, but its been over 2k kms and those codes haven't returned either. So I consider my issue resolved.

But before all that I was refusing to think it was my O2 sensor AGAIN, because I already replaced it so I figured how could it go bad again if I just changed it? That's why i was thinking of replacing the DME, LPFP, LPFP Sensor, HPFP.. and all that other stuff, if you check my threads you'll see.

Honestly, go one step at a time according to your budget. Or get the car checked by a mechanic to know the exact issue 100%. If you know your new O2 sensor is fine, try getting a continuity test on the wiring harness to the DME, it could very well be a bad wire. IMO it wouldn't hurt to replace LPFP+sensor/fuel pressure regulator if you plan to keep the car for long.

Let me know how it goes!!


Here's a quote from my thread of a checklist I made when I was having the same problems as you (What I highlighted in red is all I did in that list to fix my problem):

Originally Posted by Nexus313

Update: Car was fine after I tightened spark plugs, no more knocking, no more codes, car was running smooth.. But it took it for a long drive (100km)

Then I got some codes to popup! Again!..

The codes are: 2C3F - O2 Sensor before cat - LINE Fault, 2CAA - O2 Sensor before cat - TEMP.

So it's pretty clear, random misfires(The fact that they are always Cylinder 1-3 only), O2 codes constantly showing that I need a new MSD81 DME.

So now here's my to do list:
- Check continuity from O2 sensor plug to DME.
- Get an MSD81 DME off eBay if continuity is good.
- Replace MSD81 DME + Battery
- Replace Bank 1 O2 sensor with OEM bosch O2 sensor (I might just do all 4 to be safe)
- Replace HPFP/LPFP/Fuel pressure regular + HPFP/LPFP Sensor
- Re-Code injectors with the new DME.

What do you guys think? here is the thread which I got the information from: http://www.e90post.com/forums/showthread.php?t=1347736

I'm suspecting that the aftermarket Chinese O2 sensor + Dated JB4 chip is the cause of all these problems.

[Nexus313]

EDIT: I forgot to mention, if you have an OLD JB4 chip or JB4 with OLD firmware this can cause alot of problems! Including misfires. I had to pull out my JB4 aswell!!

[i_jihg]

This might be irrelevant but my car did the same thing months after my serpentine belt snapped and made it inside the seal. I do not remember the codes but I would get a light when engine was cold. It would run perfect and with no light once the car was warm. For me it turned out to be a clogged pick up tube. Like I said, it might be irrelevant but I just wanted to mention it. Good luck

[=C=]

I have similar symptoms as OP, however its bank1 and only when trying to WOT.
Already replaced spart plugs, coils and fuel injectors (latest index) bank1. Bank2 has originals.

Note: I dont have any error codes for o2 sensors. Which is kind of odd....

I purchased pre cat O2 sensors from ECS tune for both bank 1 and 2 however struggled to get access to the are to perform the replacement. This is a right-hand drive car so theres a steering column in the way and general access to the turbo side is hard to get too. Any recommendations how to perform this for RHD cars?

[insanesam]

Originally Posted by =C=

I have similar symptoms as OP, however its bank1 and only when trying to WOT.
Already replaced spart plugs, coils and fuel injectors (latest index) bank1. Bank2 has originals.

I purchased pre cat O2 sensors from ECS tune for both bank 1 and 2 however struggled to get access to the are to perform the replacement. This is a right-hand drive car so theres a steering column in the way and general access to the turbo side is hard to get too. Any recommendations how to perform this for RHD cars?

I previously did mine from under the car by loosening the steering rack for extra room. I found this very tedious and also my steering would be slightly off when i bolt the rack back.

Now I do it from the top using a special o2 sensor socket. I unplug the boost solenoid hoses, feed the socket onto the sensor by threading the wire through the socket gap, then attach the ratchet (flex thin/head would be better) and crack it loose. You may need to re-position the socket a few times as it is very tight down there. Once cracked loose just twist out by hand. When installing start by hand threading and be mindful not to bang or twist the wires (keep the other end unplugged). Then put the socket on and re-tighten (again re-position the socket a few times). Takes me about 5-10 mins per sensor. And yes your arms will get scrapped up a bit so wear a long sleeve.