Can someone explain why we tune in SD?
Thread Starter
Teching In
Joined: Aug 2005
Posts: 24
Likes: 0
From: Brentwood, TN
Can someone explain why we tune in SD? Hey all, my first post here. I am going to be getting a few 'go fast' goodies in the next few weeks (LGM LT headers, LS6 intake and possibly a CAM if funds are there). I have been playing around with EFILive. I understand the basics of tuning the LTFT's, but one thing that keeps throwing me off is why we (or most of us??) disable the MAF, and tune via SD? Can someone explain this for me?
Thanks!
JR
Thanks!
JR
A good example, is take a car and monitor ltrims. then, remove the maf and then log ltrims again. they will be alot different.
Anytime you can eliminate 2 things fighting against each other, the outcome will be better.
We never say it is better to fully run sd. It is just always better to tune one thing at a time. So, If you really really want your maf. Go speed density first, Get your tune set up. Then plug back in the maf and then "Fix" the maf transfer table to give you the same results you did when you where speed density and you will be set.
Anytime you can eliminate 2 things fighting against each other, the outcome will be better.
We never say it is better to fully run sd. It is just always better to tune one thing at a time. So, If you really really want your maf. Go speed density first, Get your tune set up. Then plug back in the maf and then "Fix" the maf transfer table to give you the same results you did when you where speed density and you will be set.
Thread Starter
Teching In
Joined: Aug 2005
Posts: 24
Likes: 0
From: Brentwood, TN
Thanks. So is it safe to say the MAF will attempt to correct A/F, and scew the ltft scan results?
Edit - Thanks for the super fast reply!
Edit again - I probably should have said "Is it safe to say the MAF will provide input to the PCM that will scew the ltft by forcing the PCM to adjust a/f based on what the PCM thinks it should be (because of input from the MAF)?"
Edit - Thanks for the super fast reply!
Edit again - I probably should have said "Is it safe to say the MAF will provide input to the PCM that will scew the ltft by forcing the PCM to adjust a/f based on what the PCM thinks it should be (because of input from the MAF)?"
Two reasons, two purposes. Distinguish between
getting the SD tune right, and wanting to run in
a SD-only mode.
SD tune is the "bedrock" tune and the MAF is an
overlay, in a sense. Any time MAP is unsteady
you fall right back into pure SD. Even in steady
state pulling, you may be using a blend of MAF
and SD. Tip-in, idle, etc. - all SD.
Some guys want to just ditch the MAF entirely.
That's another matter, makes the SD tune now
entirely critical (no cover-up anymore) and some
peripheral concerns like trans and timing etc.
Bottom line is, you want to keep the VE model
up-to-date with the realities of the air pump
you've built, regardless.
getting the SD tune right, and wanting to run in
a SD-only mode.
SD tune is the "bedrock" tune and the MAF is an
overlay, in a sense. Any time MAP is unsteady
you fall right back into pure SD. Even in steady
state pulling, you may be using a blend of MAF
and SD. Tip-in, idle, etc. - all SD.
Some guys want to just ditch the MAF entirely.
That's another matter, makes the SD tune now
entirely critical (no cover-up anymore) and some
peripheral concerns like trans and timing etc.
Bottom line is, you want to keep the VE model
up-to-date with the realities of the air pump
you've built, regardless.
Originally Posted by Dave F
I did it so that I could remove the restrictive MAF! Now I've got a full 4.25" inlet hose feeding my 90mm FAST TB
Thanks,
Bill
Last edited by Bill Bowling; Sep 24, 2005 at 03:49 PM.
Originally Posted by Bill Bowling
Where did you get the hose? I have a stock TB without a MAF and a SLP Lid. I sure wisked I could find something I live to go in between.
Thanks,
Bill
Thanks,
Bill
I just woke up and have a beer in one hand, a shotgun in the other, and live Rita coverage on TV !hijackI would try and locate some SS or aluminum pipe with the same ID as your TB. Between that and a few rubber couplings from Home Depot, you should be good to go.
