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Misfires At Idle (BMW 5.35i Turbo)


Kerem Erdag
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Hi There,

Finally got my car running by G4 Storm.

First of all, I apologise for the following funny explanation :)

At idle instead of running like booooooooooooooooooooooooooooooooooooooooo engine runs like booop booop booop booop always following the exact same frequency. BTW its not a non fucntional individual cylinder. When I increase the throttle engine runs OK or at least I don't feel the problem.

 

injectors 1+3+5 are connected to fuel1 and 2+4+6 are connected to fuel 2. there's a single factory bosch coil driven by bosch BIP373 igniter. trigger 1 is connected to crank vr sensor. CLT and IAT sensors are correctly connected. Fuel table is so so properly tuned that engine has around 13.5 AFR at idle. Idle valve is correctly tuned.

 

Do you have any idea of what I'm doing wrong?

 

Atacched is my pcl file.

 

Thanks in advance,

Kerem

bmw-m30.pcl

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  • 3 weeks later...

 

Hi Simon,

Now I have misfires around 1500 - 2000rpm with very light throttle. when I feel the misfire and increase the throttle a littlebit everything is just fine.

Let me summarize what I've done to fix it:

  • Distributor to coil on plug conversion: I've installed Audi S4 red coils and 4 nail Bosch iridium spark plugs. configured it to run wasted spark. Now the engine runs much more smooth, But still the misfires are there. BTW coils are tuned to have 3ms of dwell and spark edge is set to falling just as vag owner claim.
  • Lucas 300cc to Bosch 380cc D3 injectors swap: Engine is running just like a modern engine. AFR is more stable then ever. But misfires are still there.
  • Valve adjustment control: there was no problems with it.
  • Tried with a more conservative and more stable ignition map: Car didn't pull as good as the original map, but misfires are still there.
  • Changed fuel pressure and fuel master duration assuming that some type of resonance happens inside injectors causing causing them not opening properly: Nothing chaged. misfires are there in exact the same band.
  • Disabled lambda control (from the past experience I know it was creating problems with megasquirt): No change

 

Hard pulls from idle to max rpm are just fine. thus, I assume there should be no problem with cranck sensor.

 

Is there any other point that I should check? 

Thanks,

Kerem

 

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