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Discussion Starter #1
So when I run the maf test, I usually hit around 126 - 128 l/h, but it is not linear. Once I pass around 90 it jumps around (like maybe 115, 88, 119, 116, 124, 101 etc) until hitting a peak in the high 120s before redline. I have new mafs, tstat, pre-cat O2 sensors, fuel filter, and all cps have been done in the last few years (no more than 25k miles on any of them).
It pulls nicely, but then again, I have never driven an m5 that was hitting 140 l/h so not sure if I am missing something. Any advice?
 

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What is your sampling frequency?
 

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Discussion Starter #3
I have no idea. How can I tell?
 

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I mean are you just eye balling it or actually measuring a time series? My car does the same unless it's under load full throttle.
 

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So when I run the maf test, I usually hit around 126 - 128 l/h, but it is not linear. Once I pass around 90 it jumps around (like maybe 115, 88, 119, 116, 124, 101 etc) until hitting a peak in the high 120s before redline. I have new mafs, tstat, pre-cat O2 sensors, fuel filter, and all cps have been done in the last few years (no more than 25k miles on any of them).
It pulls nicely, but then again, I have never driven an m5 that was hitting 140 l/h so not sure if I am missing something. Any advice?
It shouldn't be non-linear assuming you have the pedal mashed to the floor during the whole test. It should rise steadily to redline. Is the DSC light flashing during the run? Do you feel any hesitation?
 

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Discussion Starter #6
I am wot, no hesitation, dsc off.
 

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The litres per hour reading in the secret menu is a useful test because it is calculated very rapidly by the DME based on the opening time of the injectors, so it gives an accurate fuel consumption at the moment you hit the rev limiter.

If you had a real drop from 115 to 88 l/hr, the power would have dropped from around 350 HP to 250 HP. I would have thought that would have caused a noticeable effect.

I was going to suggest your fuel pump is running a bit erratically as they do when they get old, but if the car pulls hard through the test, I don't know what is going on.
 

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The fuel table for same pedal position is different depending on load.
 
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