[M-Simon]

Hi guys,

actually I am confused with my N63 engine. When I go directly to the DME (MSD85) ECU and read out the misfire counters from all 8 Cylinders I become very fast raising data, e.g

Cylinder misfire counter
8 --127
6 --73
7 --45
1 --17
4 --17
2 --12
3 --8
5 --7

28km later --> 17miles later

117.472km
Cylinder misfire counter
8 --164
6 --92
7 --46
1 --28
4 --20
2 --16
3 --10
5 --8

But I can not feel the misfires. Only in very rare cases I can feel it.
Can anybody please have a look in their own counters?

I have the feeling that I can not trust to this counters.

Do you have any Idea what is happen here?

[larshutten]

Hi,

The counters are valid. You simply don't feel every misfire. Imagine you are driving 80km/h and there is 1 misfire it is hard to tell if it is bump in the road or misfire.

But there are some things i would like to know so you can detect your problem better.

What is your built date? Most N63 engines use the siemens injectors wich are causing a lot of troubles.

How is your colt start? it runs directly flat or a little rough?

When where the spark plugs replaced? Are there any black marks on your bobine's?

Kind regards,

Lars

[M-Simon]

Hi Lars,

-The car is from 20011 but the engine was swapped from BMW last year.
-The injectors are also from last year (the newest ones with index 12)
-The Spark plugs are new (< 7000km ) problem was there before)
-Air mass sensors are new
-Low preasure fuel sensor is new
-Both Lamda probes before catalytic converters are new
-All ignition coils are new

After a cold start the engine runs great and flat. The picture is from cyl 8.

[yzc729]

What's wrong with your car now? Is the engine jitter when driving. Or the engine fault light. Or that you can describe the car's problems clearly.

[M-Simon]

Hi,

no engine fault light. Only sometimes a missfire but a raising counter in the DME.

[bmwcare]

Hi Lars,

-The car is from 20011 but the engine was swapped from BMW last year.
-The injectors are also from last year (the newest ones with index 12)
-The Spark plugs are new (< 7000km ) problem was there before)
-Air mass sensors are new
-Low preasure fuel sensor is new
-Both Lamda probes before catalytic converters are new
-All ignition coils are new

After a cold start the engine runs great and flat. The picture is from cyl 8.

I would smoke test the intake. 99% lean misfire. You'd never 'feel' it when driving and ordinary driver would not notice

[crazybm]

Those misfires counters are real, they come from OBD2 monitors.

You can't feel them because they are so sporadic.
Per say: your highest cyl. is number 8, it had 127 counts, later it has 164 total of 37 in 27 miles of diving equals to 1.3 misfire for mile, if you are driving at 60 MPH @1000 rpm it means 1.3 misfire per minute and every 1000 revolutions.

The check engine light doesn't come up because there isn't 2 consecutive misfires and the criteria is that has to pass certain percentage of the individual cyl, reduced power to turn the light on. Means if a cylinder misfires at 30% will not turn the light on versus a 85% misfire.

Now since they a real misfires but not noticeable yet it means there is a problem coming, anything can be possible; bad coils, improperly installed spark plugs, bad injectors, sticking valves, etc. etc, you should take it to a reputable shop to look at it, sorry but in these cases can't trust the dealers since they are focused in warranties (fast money) and they aren't in for erratic problems difficult to reproduce and diagnose.

[M-Simon]

Dear Crazybm,

thank you for you analysis. I brought the car to BMW and I am now waiting for results. Last Counter after ~500km [= 310 miles] was:

CYL1 --->91
CYL2 --->35
CYL3 --->17
CYL4 --->32
CYL5 ---> 9
CYL6 --->247
CYL7 --->79
CYL 8 --->249

The foreman suspects the Injectors. from my point of view to 60% the DME is faulty because all parts incl. the engine are new. And I can not imagine that 8 injectors with newest index are dead after (30.000km / 18.000mls.)....

[crazybm]

Hi Munich Símon

Most likely defective injectors, remember the E9x N54? Injectors started with index 01 then 02, then 03 and so on....... so far are in index 12, and who knows how long the latest index will last.

Some times isn't BMW fault, it's the breaking technology, in order to make the car lighter for more performance they have to make the part as light as possible, there making it easier to fail due to many heat-cold cycles.

[bmwcare]

99% it is a lean misfire near cyl6 and cyl8.
PCV or gasket or crack or....
Smoke test the intake