Speed Density tuning?
supercharged guys always say it is easy to tune with the maf but they ussually have smaller cams and get their power from boost where the maf shines cause it measures the increased airflow. Sd tuning helps larger cam guys cause the low speed tuning sucks in closed loop. How can you stop the 02 sensors from makeing af to rich at low engine speeds, You cannot tune open at low speed and closed loop at higher rpms can you? I do with aftermarket systems but I did not think that was doable with oem ecms...is it?
Originally Posted by edcmat-l1
I believe you. I've done it many times. fuel curve flat as a table. Maxed MAF around 4000 or so. like I said, tuned around the maf. Doesnt mean it works any less, or worse, or how ever you want to phrase it. theres more than one way to make this stuff work. No real right or wrong. Just different preferences.
Exactly,
TECH Fanatic
Joined: Aug 2005
Posts: 1,691
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From: Sunny London, UK
SD will read past the maf, so you will have another string to your bow if you want/need more flexibility.
Not arguing with anyone that it cant be done. Just that SD will let you have more tools in your tunebox to play with.
Not arguing with anyone that it cant be done. Just that SD will let you have more tools in your tunebox to play with.
TECH Senior Member
Joined: Apr 2002
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From: So.Cal.
My $0.01 comment (inflation... 
)...
if the MAF is pegging out, then the AFR is "stuck" all the way from MAF pegging to PE kicking in... would that be ok...?
)...if the MAF is pegging out, then the AFR is "stuck" all the way from MAF pegging to PE kicking in... would that be ok...?
Last edited by joecar; Feb 19, 2007 at 09:06 PM.
Originally Posted by moehorsepower
What do you think the PE table is for? Exactly what it stands for , Power Enrichment. my fuel curve is flat as a board...I really don't care if you or anyone else believes me or not. I know my tune, my fueling is spot on and every other FI car I have tuned are the same..
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From: From Ohio now in that state up north
Maf or sd isnt gunna matter for most people the power differance should be very small if any. On FI cars 2/3 bar sd is better you cant argue that. However you can get by tuning the maf and 1 bar map you just peg the maf and have to get fuel from other tables.
With that big Cam and A4 setup I would recommend SD tuning.Yes,you can tune with the MAF and it will run pretty good but the air reversion could be a problem.SD will run cleaner.
As for FI you can go either way.For blowers's tuning with the MAF is fine and you can easilly tune a flat A/F that stays. Remember that a few years back there was no 2bar SD tuning and all the tuners got by no problem.We've probly got 50 or so supercharged cars out there running the MAF pegged.Some cars are 16+lbs with no drivability or fuelling problems.
Now,today they have 2 bar SD setup's that I see really benefiting turbo setup's.This way you don't have to tune just 1 boost level.You can tune 1 -35lbs of boost accurately. Good stuff
As for FI you can go either way.For blowers's tuning with the MAF is fine and you can easilly tune a flat A/F that stays. Remember that a few years back there was no 2bar SD tuning and all the tuners got by no problem.We've probly got 50 or so supercharged cars out there running the MAF pegged.Some cars are 16+lbs with no drivability or fuelling problems.
Now,today they have 2 bar SD setup's that I see really benefiting turbo setup's.This way you don't have to tune just 1 boost level.You can tune 1 -35lbs of boost accurately. Good stuff
Originally Posted by beardWS6
Thats what I was thinking. My 250 255 640 640 112 would benefit from a SD tune. Thanks! Plus mine being a A4 won`t help any! Thanks!
beard... our cams are very similar... my car runs 1000000 times better in SD at idle due to the way the cam works it throws the maf all over the place trying to correct airflow at low RPM's... SD tune cures that.
or at least thats the way i understand it hehe
or at least thats the way i understand it hehe
I guess I'll be the lone MAF supporter. I still run a MAF with my A4 402 and the car starts (even in 20 degree weather), idles and drives great and can get 18-19 mpgs on the hwy with 3.73 gears.
You are NOT the lone maf supporter. Redundant sensors are good -- just ask the NASA people. However, if that sensor is maxed, or is in some other way compromised (reversion pulses), then go with what works BETTER, not with what just "works".
Originally Posted by DrkPhx
I guess I'll be the lone MAF supporter. I still run a MAF with my A4 402 and the car starts (even in 20 degree weather), idles and drives great and can get 18-19 mpgs on the hwy with 3.73 gears.
Originally Posted by gametech
You are NOT the lone maf supporter. Redundant sensors are good -- just ask the NASA people. However, if that sensor is maxed, or is in some other way compromised (reversion pulses), then go with what works BETTER, not with what just "works".
Originally Posted by DrkPhx
That's good to know. The MAF reading is maxed at WOT, however I believe it's because of the 98 OS not capable of reading that high and not limited by the MAF itself.
That's a bit of a misnomer; the OS's cap is THE effective cap. There is no work around, bigger MAFs still cannot be sampled any higher.
