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misfires at idle

308 Views 8 Replies 4 Participants Last post by  cEnberg1
Let me clarify by saying I'm not a dumb buyer and when I picked this car up for 2500$. I thought it was a steal. No check engine light idled perfectly at 750. now after 200 miles. It sounds like someone put in the largest cam profile allowable idling 600. Are idle misfires common? I looked at the computer and the adaptations haven't changed so I don't think there's a vacuum leak. Any possible answers?
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Are there any trouble codes in the engine DME?

What are the hot idle adaptations:
  • Short term fuel trim bank 1 %
  • Long term fuel trim bank 1 %
  • Short term fuel trim bank 2 %
  • Long term fuel trim bank 2 %
  • RPM
  • MAF flow in g/s
I'll have to get back to you on that. When I'm clicking through it. it sometimes doesn't let me read it. says something like "ECU non-compatible something something" I don't quite remember. ill have to go check. plus half of it is in german so it takes me a sec lol
Are there any trouble codes in the engine DME?

What are the hot idle adaptations:
  • Short term fuel trim bank 1 %
  • Long term fuel trim bank 1 %
  • Short term fuel trim bank 2 %
  • Long term fuel trim bank 2 %
  • RPM
  • MAF flow in g/s
So im still learning how to click through inpa but heres what i found. the error code says "combustion misfires when the tank level is low" so i go to look at them.
Rectangle Font Line Slope Screenshot


And that is what I see. Not sure what I'm seeing but 99% sounds full not "low level" idk
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It sounds like your codes are for "misfire with fuel cut off". In other words, the cylinder is misfiring so often that the DME has cut the fuel off of that cylinder to stop damage from occurring. It resets after turning the engine of and back on again.

The 99% values are for the O2 sensor heater systems and that's good values.

The Multiplikative values of 12% is too high. It's indicative of a vacuum leak or a failing fuel pump. Both require the DME to add extra fuel.

Follow the misfire guide linked in post #4
I have a second BMW that i have been trying to sell for a while now but was unsuccessful on Facebook. I saw the marketplace on this forum but is unauthorized to create a listing. i understand my account is new is authorization achieved through age like facebook or no?
You have an exact error code for the error you provided?

INPA is a bit difficult to understand, and therefore it would be better to use a universal scanner for this purpose. I also don't have one and I'm using INPA as well for diagnosing, but what INPA is showing and also how they are providing the data (in what range and in what format) can differ between the engine computers used for these engines, like M52TU and M54. Maybe even your INPA version has influence on this as well. But at the end also with INPA you can find the data you need.

I wil try to explain the meaning of the valuable things in the picture you shared. There are 3 important values here, which are:

  • Additive adaptionsfaktor - This is your long term fuel trim for idle engine speeds.
  • Multiplikative Adaptionsfaktor - This is your long term fuel trims for higher engine speeds
  • correction injection time - this is your short term fuel trim

It looks like your short term fuel trim and your long term fuel trim for idle positions (I'm assuming your screenshot is made while your engine was running idle) are way to high. This compared to your long term higher load engine speed fuel trims, I assume you have a vacuum leak somewhere. So my recommendation would be to get a smoke test done (or make a DIY smoke tester) and fix your vacuum leaks first. After that I think your engine should run a lot better!
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You have an exact error code for the error you provided?

INPA is a bit difficult to understand, and therefore it would be better to use a universal scanner for this purpose. I also don't have one and I'm using INPA as well for diagnosing, but what INPA is showing and also how they are providing the data (in what range and in what format) can differ between the engine computers used for these engines, like M52TU and M54. Maybe even your INPA version has influence on this as well. But at the end also with INPA you can find the data you need.

I wil try to explain the meaning of the valuable things in the picture you shared. There are 3 important values here, which are:

  • Additive adaptionsfaktor - This is your long term fuel trim for idle engine speeds.
  • Multiplikative Adaptionsfaktor - This is your long term fuel trims for higher engine speeds
  • correction injection time - this is your short term fuel trim

It looks like your short term fuel trim and your long term fuel trim for idle positions (I'm assuming your screenshot is made while your engine was running idle) are way to high. This compared to your long term higher load engine speed fuel trims, I assume you have a vacuum leak somewhere. So my recommendation would be to get a smoke test done (or make a DIY smoke tester) and fix your vacuum leaks first. After that I think your engine should run a lot better!
Thanks that’s what I decided to do. will probably get to it next week I’m currently fixing the suspension on my truck. Thanks for the help.
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