BimmerFest BMW Forum banner

1 - 15 of 15 Posts

·
Registered
Joined
·
11 Posts
Discussion Starter · #1 ·
All,

First let me tell you that I can't thank you enough for the knowledge I have obtained from you over the last year I have owned my BMW 330i. Just as a background the car is a 2005 with 115K on it, bought it with 99K on it.

Ok so I am throwing the P0171 (Bank 2 too lean) code as well as a gas smell that has progressively gotten worse over the last 3-weeks.

This is not my first go around with the Banks running to lean. Last year I was throwing both error codes (Bank 1 & 2 too lean) which has already led me to do the following within the last 8-months to the car:
-Replaced rubber intake boot (was cracked)
-Cleaned MAF many times
- Checked and cleaned DISA Valve
- Used blue gasket sealer to create new seal for DISA Valve
- Replaced fuel filter
- New spark plugs
- Replaced fuel pump (not due to being too lean but it went out a few months ago)
- Checked fuel rail for pressure

After doing all this the Bank 1 & 2 codes went away for about 6-months. Then just about 3-weeks ago the car threw the check engine light again and this time it was just Bank 2 is too lean. About this exact same time I started to notice a gas smell when starting and while driving the car. Twice I have also noticed what appears to actually be fuel that has leaked on my garage floor after the car being parked (not a ton but enough to make me worry) I reset the code after cleaning MAF and and doing a normal oil change, then it came back on about 4-days latter and the gas smell has progressively gotten worse.

I am at my ends wits!! Please any help or suggestions would be appreciated.
 

·
Registered
Joined
·
253 Posts
I would check the hoses on the Crankcase Ventilation Valve, these can cause the lean codes.
Check the vacuum hoses from the fuel filter to the engine and the fuel tank purge/vent valve for your gas odor.
 

·
Coupe OR Never
Joined
·
1,445 Posts
Man you saying the fuel smell started recently (I imagine it wasn't there before the fuel filter change). I would first look at the fuel filter plumbing and see if there is any leak there.
Fuel leak enough would definitely make me worried but one good thing is that it shouldn't be hard to find the leak. You saying you saw a fuel on the garage floor!.. Hey time to get under and see where it is leaking. I would start at the fuel filter and follow from there...

P.S. I have the code P0174 (bank 2 lean) Been living with it for over 2 years by now. It shows up about once a month. I can't find the issue, dealer wants to replace the engine(if you know what I mean:)) to fix it...
 

·
Registered
Joined
·
623 Posts
Clean your idle control valve and replace the rubber grommet it pops into. I know when I cleaned my ICV, I didn't get it all the way pushed back into the rubber grommet. When I started the car, I certainly smelled gas, and had some other problems. Also, like others have said, get under it with a flashlight and see if you can figure out where the leak is coming from.

If you have a water heater with a pilot light or a gas dryer in your garage, might want to park your car outside for a while.
 

·
Coupe OR Never
Joined
·
1,445 Posts
Well, he says he smells fuel and he sees fuel on his garage floor. The cause of smell is actual fuel leak. I can't see how an ICV cause fuel smell. It should only control the amount of air that goes in when the car is idling. If it was me, I would focus on the source of the fuel leak first. Seeing fuel on the garage floor is not good...
 

·
Noone Special
Joined
·
673 Posts
OP the fuel leak is the reason for the bank 2 lean. fix the leak and it will be fine.
 

·
Registered
Joined
·
11 Posts
Discussion Starter · #7 ·
All,

Thanks for the suggestions. Heading out to by friend's shop to lift the car up so I can walk under it and really get a good look at the fuel filter, fuel lines, reserve tank valve, etc. I'll post back in a few hours to let you know what I find.

Also I won't probably get to it today, but checking and cleaning the crank case valve and the idle control valve. Those two might also be culprits, but I do want to make sure I get the gas leak/smell address first and foremost.

Thanks again and I'll let you know what I find.
 

·
Registered
Joined
·
11 Posts
Discussion Starter · #8 ·
So after putting the car up on my friend's lift and checking all the fuel hoses I did notice some marks on the gas tank (passenger side) that appeared as if gas was running down it and then dripping off.

I even started the car up on the lift and let it run for awhile to make sure there was not any noticeable leaks, and nothing at the moment.

Popped the hood and could not smell any gas smell while running or stopped.

Then lifted up the back seat to check the seal around the fuel pump that I replaced 3-months ago. Once I lifted up the seat the gas smell became a lot stronger and after taking off the metal round black plate with the four bolts I could tell that the gas was leaking around the seal of the fuel pump.

When I replaced the fuel pump I did not receive a new rubber gasket nor a new metal ring that screws it down tight so I used the old one and remember having trouble getting is seated right.

Also used my friends Actron auto scanner which gave me more detail than the Bank 2 too lean that I got when I used the one from Autozone. It pulled P0456 - evap system very small leak, and P2227 barometric pressure ckt rng/perform.

So I think what happened is that when I would top off the tank I would notice twice some gas marks on the rear passenger side of the garage floor. It probably was the gas coming up and leaking out of the seal then running down the outside of the gas tank and dripping on the floor.

In not being sealed properly the fuel system is not getting the proper pressure all the way up to the fuel rail thus the P0456 code (that and I am going to replace my gas gap just to be safe).

Next step are to go the the dealership and get a new rubber gasket and metal o-ring so that it will seat properly and new gas cap to see if this does the trick.

Any other suggestions? Sorry for such a long post.
 

·
Seek to understand,^Value
Joined
·
25,199 Posts
I don't know anything ... but I can read.

So, I read over a hundred misfire threads and put together this diagnostic tree for the E39 covering EVERY SINGLE ANSWER given in those threads.

No answer was left out. So, the problem should be 'one' (or more) of the items listed in that thread.

For completeness and consistency, I point the OP to this which can easily be found simply by performing a quick /misfire(F3) in the VERY best of E39 Links:

- How to diagnose a BMW E39 engine misfire (1)

By way of example, here is an excerpt:
BMW E39 engine misfiring is ALWAYS due to one of the following:

  • gas
  • air
  • spark
  • compression
  • timing
Tribal summary on BMW E39 specific misfire culpability: (after reading hundreds of E39 misfire threads and manually collating the results)

  1. bad fuel [air:fuel ratio]
  2. clogged fuel filter [air:fuel ratio]
  3. bad fuel pump [air:fuel ratio]
  4. clogged engine air filter [air:fuel ratio]
  5. vacuum leaks in hoses [air:fuel ratio]
  6. bad coil packs [spark] (1)
  7. bad coil boots [spark]
  8. bad or ill fitting spark plug valve cover seals [spark]
  9. worn or fouled spark plugs [spark]
  10. bad mass air flow (MAF) sensor or meter [air:fuel ratio]
  11. bad DISA valve flap [air:fuel ratio] (1) (2)
  12. bad DISA valve o-ring [air:fuel ratio] (1) (2) (3)
  13. worn fuel injector seals (o-rings) (1) (2)
  14. bad fuel injectors [air:fuel ratio]
  15. bad 02 oxygen sensors [air:fuel ratio]
  16. cracked rings [compression]
  17. bad camshaft position sensor CMP, aka CPS [spark? timing?]
  18. bad crankshaft position sensor CKP, aka CPS [spark? timing?]
  19. bad ground wires [spark]
  20. bad fuse or relay [gas, spark, timing]
  21. bad electrical wiring [gas, spark, timing]
  22. bad engine computer DME, aka ECU [spark]
  23. intake manifold gasket leak [compression, air:fuel ratio]
  24. bad crankcase oil separator valve CCV, aka PCV [air:fuel ratio]
  25. bad idle control valve ICV [air:fuel ratio]
  26. bad throttle position sensor TPS [air:fuel ratio]
  27. bad VANOS seals [compression, air:fuel ratio]
  28. valve cover gasket (VCG) leak [air:fuel ratio]
  29. head gasket leak, or a cracked block [compression, air:fuel ratio]
BMW E39 tribal knowledge misfire-troubleshooting algorithm:

  • If your engine is misfiring, immediately turn off the ignition
  • Wait 30 seconds before restarting the engine (this reputedly resets emissions-related fuel cutoffs)
  • Note the presence or absence of a yellow solid or blinking SES light
  • Scan for diagnostic trouble codes, aka DTCs (1) (2) (3) (4) (5) (6)
    • Write down any "stored" DTCs & do a search for hints (1) (2)
    • Write down "pending" DTCs & do a search for hints
    • Clear all stored & pending DTCs to see if they return in time
  • Reset engine electronics by disconnecting the battery & crossing the cables (with a wrench) for 10 minutes (1)
  • Fill your fuel tank with gasoline from a different gasoline station
If you have a specific-cylinder misfire code:

  • Swap ignition coils between adjacent cylinders (1)
  • Swap spark plugs between adjacent cylinders.
    • If the misfire moves, replace the spark plugs
  • Swap the spark plug boots between adjacent cylinders
    • If the misfire moves, replace the spark plug boots
  • Swap the fuel injectors between adjacent cylinders
    • If the misfire moves, clean or replace the fuel injectors
    • Replace the fuel-injector seals (aka o-rings) (1)
  • Check compression differences between cylinders (1)
    • If the misfire cylinder is lower than the rest, squirt heavy duty oil in the cylinder to check the rings
At this point, we're no longer dealing with specific cylinder misfires.

Multi-cylinder system & specific component tests:

  • Test the engine air filter
    • Temporarily remove the engine air filter
    • If the stumbling disappears, replace the engine air filter
  • Test the Mass Air Flow meter (MAF) (1)
    • MAF faults often set fuel trim faults (1)
    • Temporarily disconnect the MAF & drive the vehicle (1)
      • If the misfire changes, clean the MAF (1)
      • Replace the MAF if necessary
  • Check the hose from the MAF to the engine for leaks
  • Check for a cracked "T-connection after the MAF sensor"
    • If bad, replace the T connection
  • Test the idle control valve (ICV)
    • An overly rich fuel:air ratio can cause the ICV to stick (1)
    • A sticking ICV can lay a coat of soot on the O2 sensors (1)

  • Test the fuel pump
    • Connect a pressure meter to the fuel delivery rail (1)
    • Jump 30 & 87 & feel hoses for fuel delivery (1) (2)
      • If bad, replace the fuel pump
  • Check for vacuum leaks
    • Run the "intake manifold vacuum leak test" (1)
    • Visually inspect all vacuum hoses
      • If any are bad, replace
      • Cracked CCV hose vacuum leaks often affect cylinders 1, 2, & 3 (1)
  • Test or clean the CCV (aka CVV oil separator valve) and its hoses (1)
    • If bad, replace the CCV
    • CCV faults often set fuel trim faults (1)
  • Test the CMP (confusingly aka CPS) camshaft position sensor (1) (2)
    • The CMP will set a fault when it is bad (1)
    • If bad, replace the CMP
  • Test the CKP (confusingly aka CPS) crankshaft position sensor ... (1)
    • If bad, replace the CKP
    • The CKP will set a fault when it is bad (1)
    • The CKP often prevents starting (1)
  • Test the TPS "throttle position sensor" ...
    • If bad, replace the TPS
  • Test oxygen sensors (1)
    • Best way is to scan them for values (1)
    • Pre-cat o2 sensors fail much more than post cat (1)
  • Test the I6 VANOS seals (by disconnecting the harness connector)
    • It's not a bad idea to replace the I6 VANOS seals anyway
  • Test fuel delivery pressure
    • If low, test and/or replace the fuel filter
    • A clogged fuel filter often set fuel trim faults (1)
  • Check the DISA valve for midrange operation
    • Remove DISA valve and check plastic flap for operation (0) (1) (2) (3) (4) (5) (6) (7) (8) (9)
    • Replace the DISA valve o ring (1) (2) (3)
    • Replace the DISA valve if necessary (1) (2) (3)

  • Check the "valve cover gaskets (VCG)
    • Spray carburetor cleaner on while engine is running (1)
    • If idle improves, replace VCG
  • Check the "intake boot" for cracks
    • If bad, replace
  • Just before you get down on your knees for pious pleas to the Lord Jesus, go ahead, add a bottle of Seafoam or Techron concentrate to the fuel & see if that improves the misfire.
  • If you get this far, and you still haven't located or resolved your misfire, you actually now have a bona-fide 'new' problem that has not yet been seen in the Bimmerfest E39 forums!
    • If you got this far, then open a misfire thread on Bimmerfest!
BTW, if the answer is NOT in that thread, then we should ADD it to that diagnostic tree so that the NEXT person gets a complete and comprehensive answer!
 

·
Registered
Joined
·
3 Posts
Man you saying the fuel smell started recently (I imagine it wasn't there before the fuel filter change). I would first look at the fuel filter plumbing and see if there is any leak there.
Fuel leak enough would definitely make me worried but one good thing is that it shouldn't be hard to find the leak. You saying you saw a fuel on the garage floor!.. Hey time to get under and see where it is leaking. I would start at the fuel filter and follow from there...

P.S. I have the code P0174 (bank 2 lean) Been living with it for over 2 years by now. It shows up about once a month. I can't find the issue, dealer wants to replace the engine(if you know what I mean:)) to fix it...
I had the same problem on my 2001 525 wagon; code for only one bank. Replaced the CCV and suspect hoses, sealed Disa gasket, on and on to no avail. Finally replaced pre-cat O2 sensors since only one bank was coding
and got the proper fix.
 

·
Registered
Joined
·
2,064 Posts
I had the same problem on my 2001 525 wagon; code for only one bank. Replaced the CCV and suspect hoses, sealed Disa gasket, on and on to no avail. Finally replaced pre-cat O2 sensors since only one bank was coding
and got the proper fix.
Well, the issue is [the] generic code reader. It gives you a generic code and thus the solution becomes 'generic' if you catch my drift. The OP finally used a proper scanner that showed the specific problem and thus point to a specific solution. :)
 

·
Registered
Joined
·
4 Posts
Same problem. 2014 750LI with 101k miles. Codes P0174 abd P01C8

replaced:
02 Sensors (all 4)
spark plugs (all 8)
ignition coils (all 8)
checked for vacuum leaks, and have suction at oil cap while running
cleaned MAS
Fuel rail pressure is at 121-124psi
misfires seem to happen mostly in bank 2
with the diag tool I have, I can cut off injectors individually and each one of the 8 you can feel it/hear it, so they are all working..

Where is the DISA valve? Any other suggestion?

MUCH appreciated!!
 

·
Registered
Joined
·
308 Posts
OP the fuel leak is the reason for the bank 2 lean. fix the leak and it will be fine.
This ^^^

You already said you have fuel on your garage floor. Fix all known problems before further troubleshooting. Gas on your garage floor is a known problem.
 
1 - 15 of 15 Posts
Top