[hicazkar]

make smoke test and check air leaking on intake systems

[bmchicago]

this looks normal to me. Accumulated misfires is normal. It must increase exhaust emissions by more than 50% before it will store a code for misfire.

Emission Limit: (3.2.2) If the sum of cylinder(s) misfire counters within 1000 revolutions is 4 times exceeding a predetermined value during a driving cycle, or during the first 1000 revolutions, the fault code for emission relevant misfiring is temporarily stored. If the following driving cycle is also above the emission limits, the MIL will be switched on and a cylinder selective or global fault will be stored.

[bmwlover]

make smoke test and check air leaking on intake systems

Cars does not have any problem. My question is about ista.

[Node]

I DON'T see any sensible question about ISTA here. It does NOT invent numbers. Just shows what engine control unit tells!

Unit does not tell about stored fault - ISTA shows empty. Unit reports misfire number - ISTA shows them as they ARE.

[bmwlover]

I DON'T see any sensible question about ISTA here. It does NOT invent numbers. Just shows what engine control unit tells!

Unit does not tell about stored fault - ISTA shows empty. Unit reports misfire number - ISTA shows them as they ARE.

Then why should 8 car's dme tell to ista this? They all have misfires?  Why ista reports misfire, is this normal? Checked today on new bmw, only 580 miles on it, same happens. Is this normal for new car too?

[Node]

It was ALREADY told here the firmware of engine control units of these early N engines have EXTREMELY sensitive misfire detection. So it's ok for one or two misfires to be detected by engine control unit firmware over some time. Don't INVENT problems where there are none, unless you FEEL the misfires happening.

P.S. It's not that easy to definitely detect misfires! The only way that can be done is measuring impulse timings from crankshaft sensor. And then you need to do that to mostly microsecond precision!!! And unit needs to measure these while keeping engine running, etc.

P.P.S. And then if firmware detects 1 microsecond deviation from previous cycle... well, it's misfire. Does that matter? It's FOR YOU to decide. By default firmware ignores singular non-repetitive misfires as these are probably just noise... Maybe that 1ml of fuel injected was a bit different composition, maybe wind gusted and there was 0.1% more air in the cylinder at that specific moment...

[bmchicago]

I DON'T see any sensible question about ISTA here. It does NOT invent numbers. Just shows what engine control unit tells!

Unit does not tell about stored fault - ISTA shows empty. Unit reports misfire number - ISTA shows them as they ARE.

Then why should 8 car's dme tell to ista this? They all have misfires?  Why ista reports misfire, is this normal? Checked today on new bmw, only 580 miles on it, same happens. Is this normal for new car too?

i think the problem you have is you "think" that a car should never misfire. When in reality that it is perfectly normal for engines to misfire. There is no such thing as a perfect engine, perfect ambient conditions (air density, fuel pressure)

What you should do is learn about OBD and EOBD regulations on when the engine computer will report an error.

Ista is doing its job to report running status.

also check SIB 04 15 18

[bmwlover]

Thank you, problem solved

[ferbmw]

Thank you, problem solved

Pls, how did you solve it ?

[bmwlover]

Thank you, problem solved

Pls, how did you solve it ?

I read the sib what is listed above. All car have such misfires and it is normal.