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Title: ME7.1 b5 s4 maf tuning Post by: maxc777 on June 11, 2018, 01:35:55 AM Hi guys,
I recently started learning how to tune my b5 s4. I have fitted EV14 550cc injectors, 85mm maf, and k04 turbos. ive scaled the injectors 0.056 krkte and altered the tvub according to the forums. it worried me that it runs so well with out scaling the maf, even though im running the 85mm housing. i scaled the maf tonight by upping the MLHFM table by 1.356 and it runs terribly hunting and stalling, also threw the MAF signal too high fault. im confused as to why this is... as it seems the normal thing that most people do. yet it ran so well with the maf no scaled. Title: Re: ME7.1 b5 s4 maf tuning Post by: nyet on June 11, 2018, 02:06:08 AM Hitachi or Bosch MAF?
If Bosch, take into account that MLOFS is non-zero. Also, what are your STFTs and LTFTs? Title: Re: ME7.1 b5 s4 maf tuning Post by: maxc777 on June 11, 2018, 03:49:30 AM It’s Bosch MAF.
After altering my tvub it’s 3% st and 7% lt I thought that was what the offset map was for the Bosch or hitachi or does that alter the linearisation map Sent from my iPhone using Tapatalk Title: Re: ME7.1 b5 s4 maf tuning Post by: nyet on June 11, 2018, 08:49:45 AM It’s Bosch MAF. After altering my tvub it’s 3% st and 7% lt I thought that was what the offset map was for the Bosch or hitachi or does that alter the linearisation map Sent from my iPhone using Tapatalk You cannot simply scale MLHFM. Please reread the s4wiki, or try to understand exactly what MLOFS is. Title: Re: ME7.1 b5 s4 maf tuning Post by: maxc777 on June 11, 2018, 03:06:26 PM I was struggling to understand the wiki.
The way I read the mlofs is to subtract 200 scale it and then add 200 again. But I don’t understand how this works as most of the mlhfm table has values less than 200 so I’ll end up with a negative number. Sent from my iPhone using Tapatalk Title: Re: ME7.1 b5 s4 maf tuning Post by: nyet on June 11, 2018, 03:10:42 PM Err that might be incorrect, as you rightly point out. You may have to add a scaled 200 back so the minimum value (-200 * scale) is 0 again.
I should really edit that part of the wiki. I have to think on it, I don't have a Bosch MAF Basically the final curve should have the following two properties: 1) the minimum value should not be negative 2) the voltage that resulted in MLHFM + MLOFS == 0 should still result in zero. Does that make sense? Title: Re: ME7.1 b5 s4 maf tuning Post by: maxc777 on June 11, 2018, 03:16:02 PM Down the low end of the table it has values like 6g/s
6-200 = -194 Scaled *1.356 = -260 Add the 200 back and we are back at -60 I may be reading it wrong. Sent from my iPhone using Tapatalk Title: Re: ME7.1 b5 s4 maf tuning Post by: nyet on June 11, 2018, 03:25:13 PM Down the low end of the table it has values like 6g/s 6-200 = -194 Scaled *1.356 = -260 Add the 200 back and we are back at -60 I may be reading it wrong. Sent from my iPhone using Tapatalk No, you aren't wrong. My brain is a bit frazzled, but the idea is that whatever the result of MLHFM+MLOFS is, the new one is scaled by 1.35 compared to the original MLHFM+MLOFS. Offhand I can't think of what rules will result in that, but thats the end goal. Title: Re: ME7.1 b5 s4 maf tuning Post by: nyet on June 11, 2018, 03:27:01 PM Maybe I'm an idiot and it really is scale both MLHFM and MLOFS by 1.35 (no shifting around). Have to think on it.
Title: Re: ME7.1 b5 s4 maf tuning Post by: maxc777 on June 11, 2018, 04:09:47 PM I’m still confused as to why the car runs so well with the MAF not scaled. Fuel trims are a bit off but I thought it would run terribly.
Sent from my iPhone using Tapatalk Title: Re: ME7.1 b5 s4 maf tuning Post by: nyet on June 11, 2018, 04:11:39 PM I’m still confused as to why the car runs so well with the MAF not scaled. Fuel trims are a bit off but I thought it would run terribly. Sent from my iPhone using Tapatalk Not sure either, but it may illuminate other issues in your set up that you do not know about when you do get the proper MAF scaling (FPR issues, leaks etc). |