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Title: Difference between maf readings.. Post by: vwaudiguy on March 31, 2018, 09:41:45 PM Of an OEM airbox, and an open filter with 10" of straight section between the filter and maf. Hardware and software are identical besides the pre-maf piping/filter, and the car with the lower maf readings has a 3" downpipe vs. 2.5" on the higher reading car. Both logs were taken using the same maf sensor swapped between the two cars. Logs were taken 20 minutes apart. Before I go digging for intake leaks between the turbos and maf on the lower reading car , does anyone have an opinion if there should be this large a difference? I don't normally deal with open element setups, but have done a handful of stock airbox cars with this same hardware combo.
Details: Stock block 2.7T BW K04 85mm straight maf housing Thanks, guys. Title: Re: Difference between maf readings.. Post by: SB_GLI on April 01, 2018, 06:11:35 AM How do the raw maf voltages compare between the two?
Title: Re: Difference between maf readings.. Post by: rnagy86 on April 01, 2018, 06:20:56 AM The baseline is the OEM RS4 airbox with a paper filter, then I've installed the x34 intake and put a HKS mushroom filter, as you can see
the turbulent air makes the MAF read low which in turn makes the AFR lean out, then went with a conical BMC filter, which would foul the MAF and read higher, which makes the AFR rich, then installed the AEM dryflow which is provided with the kit, and this is the only filter that comes with a built-in velocity stack and that helps a lot. (http://i.imgur.com/BISIdeY.png) Title: Re: Difference between maf readings.. Post by: vwaudiguy on April 01, 2018, 07:29:48 AM How do the raw maf voltages compare between the two? Looks to be about the same difference. Title: Re: Difference between maf readings.. Post by: vwaudiguy on April 01, 2018, 07:34:38 AM The baseline is the OEM RS4 airbox with a paper filter, then I've installed the x34 intake and put a HKS mushroom filter, as you can see the turbulent air makes the MAF read low which in turn makes the AFR lean out, then went with a conical BMC filter, which would foul the MAF and read higher, which makes the AFR rich, then installed the AEM dryflow which is provided with the kit, and this is the only filter that comes with a built-in velocity stack and that helps a lot. (http://i.imgur.com/BISIdeY.png) Looks like your results are very close to what I'm seeing. This would also explain a few things on a few other cars, and not pegging the maf despite having very similar hardware and boost levels. I made a graph with 5 different cars all using the same housing, and the one with the open element was the only one much lower than the other 4 by about 75 g/s. Title: Re: Difference between maf readings.. Post by: KasperH on April 01, 2018, 02:58:14 PM If this is a general thing, I'm throwing my cone filter in the bin and installing stock box right away.
Or could a velocity stack cure this problem? I will try and make logs back to back with stock box and cone filter to see if this also applies to 1.8T(why wouldn't it?) Title: Re: Difference between maf readings.. Post by: nyet on April 01, 2018, 10:26:38 PM ;D
Title: Re: Difference between maf readings.. Post by: KasperH on April 03, 2018, 07:23:49 AM im seeing the inverse.
Cone filter has higher readings despite higher intake temps? |