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Discussion Starter · #1 ·
Hi All,

I have had my car for 18 months its got 300k kms on the clock been driving well untill some 400kms ago. The fuel gauge became faulty giving false readings, car suddenly lost power on an uphill on one of my drives and I assumed i was running low on fuel. Waited a while and restarted the car it was misfiring, drove the car to the nearest fuel station refueled and the car was okay. The problem became more frequent at times the car would just cut off when idling and required a great deal of patience to start it. When cold it starts well but after 5kms or so it would start misfiring again took it in for diagnostics and did not find any joy.

It seemed like there was a leak somewhere on the intake manifold because after spraying a strong brake disk cleaner the revs would go up but even that test was not consistent. The mechanic replaced the centrifugal oil seperator and there was no change.
I have since discovered that if I keep running it for say a km or two after it starts misfiring the car will clear the misfire when I start it again but this will last about 8 to 14kms before the misfire comes back again.
Out of desperation I took out the catalytic converters because I could pick up a smell like battery acid, assumed it was the cats so took them out. The problem went away for 40km and it started again and the smell is still there.

I need your help what do I do????????????
 

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Discussion Starter · #4 ·
Ooops sorry my bad, I did not use the break cleaner when spraying into the intake for that I used engine quick start. Used the cleaner when I was scoping around the manifold. I have changed the air filter, checked the coils they are all okay, replaced the plugs checked the fuel pump and regulator and those seem fine. I will reclean the Idle control valve and replace the O2 sensors. What bewilders me is why it is so intermittent????

I will look at the air intake boot and replace it as you guys suggest. It is driving me nuts!!!!!!!!!!!!
 

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What bewilders me is why it is so intermittent????
If I had an intermittent misfire, I'd look for the answers here:

- How to identify all BMW computer-specific OBDII fault codes (1) & how to better understand the key EPA federal test procedure (FTP) concept of the BMW "drive cycle" (1) & how to diagnose a typical BMW E39 engine misfire (1) or a sporadic-temperature-change cold-engine intermittent misfire (1) obtaining the pending or diagnostic trouble code (DTC) using free or freeware scans (1) [except in California or Hawaii (1) (2)] or the cheapest ODII scanner in the world (1) (2) or a better overall scanner (1) or the best diagnostic tools (1) (2) (3)
 

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Ooops sorry my bad, I did not use the break cleaner when spraying into the intake for that I used engine quick start. Used the cleaner when I was scoping around the manifold. I have changed the air filter, checked the coils they are all okay, replaced the plugs checked the fuel pump and regulator and those seem fine. I will reclean the Idle control valve and replace the O2 sensors. What bewilders me is why it is so intermittent????

I will look at the air intake boot and replace it as you guys suggest. It is driving me nuts!!!!!!!!!!!!
What about your Cam Position Sensor? Mine misfired and hesitated upon acceleration when it went bad, but I'm wondering if that could be a contributor? Have you ever replaced it?
 

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

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]
  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)
  12. bad DISA valve o-ring [air:fuel ratio] (1)
  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)
    • Replace the DISA valve o ring (1) (2) (3)
    • Replace the DISA valve if necessary (1) (2)

  • 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 know what to do (see above)
 

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Discussion Starter · #10 ·
Thanks Bluebee, Its quite an exhaustive check but I will do as much as I can before taking it in. Another interesting thing about the misfire is that it's only affecting cylinders 5,3 & 1. Could this mean something guys?????
 

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Discussion Starter · #11 ·
Well well well I am back after some silence, Took the car in for diagnostics to a different guy and initially the guy said Camshaft sensor and ECU are faulty but this was just on the reciept and he quoted me R6200 to fix the problem so I said NO! on the suspicion that he was ripping me off and asked him to provide me with the diagnostics report to which he redid the diagnostics only to get the one error with the Crankshaft sensor. After this the guy told me the other faults might have been cleared and they will come back after i have run the car just do not know how far true that is????????????? Any Comments from you guys??
 

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Camshaft sensor and ECU are faulty but this was just on the reciept ... get the one error with the Crankshaft sensor
Hmmm... camshaft (CPS, or more accurately, CMP):
- How to replace your camshaft position sensor (CPS) in the E39 (02 530i) (98 540i) (M62 98 540i) (98 528i) (530i) & E46 (1) & ('99 740iL)

Or crankshaft (CPS, or more accurately, CKP):
- Crankshaft position sensor replacement (2002 e39 530i)
- Crankshaft Pulse Generator replacement

HINT: NONE of what you will hear is NOT in the misfire diagnostic thread (i.e., the sum total of all culprits is in the misfire thread - the reason I know that is I read scores and scores of threads to create that diagnostic tree - and I left nothing out that was proposed in those hundreds of threads).
 
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