When tuning off the MAF...
Thread Starter
On The Tree
Joined: Apr 2002
Posts: 179
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From: Baltimore, MD
When tuning off the MAF... is it better to adjust the MAF translation function or the Injector Flow Rate?
SlowCar suggests that the IFR is pretty well-known and LS1-Edit documentation says not to touch IFR if you're not changing the injectors, but I've seen people talking about doing it that way.
Thanks.
SlowCar suggests that the IFR is pretty well-known and LS1-Edit documentation says not to touch IFR if you're not changing the injectors, but I've seen people talking about doing it that way.
Thanks.
People use the IFR table because its a lot more straight forward than tuning the MAF table. IFR changes are blanket changes and affect both PT and WOT fueling where the MAF can be effected by a number of variables. Variables in which we have no idea what the new values may have changed to....
The MAF table affects transmission and timing
while the IFR affects only fuel. But if you have
no reason to suspect fuel modeling error then
you should figure out what -is- out of bed and
attack that, by its most-representative "handle".
while the IFR affects only fuel. But if you have
no reason to suspect fuel modeling error then
you should figure out what -is- out of bed and
attack that, by its most-representative "handle".
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A problem I have tuning with the IFR or MAF table is if you are running a modified intake that is throwing you "lean", and it is dumping extra fuel in, but your VE table is running you rich, then you are just creating an even more excessively rich condition whenever the VE table is referenced. Just a thought.
Thread Starter
On The Tree
Joined: Apr 2002
Posts: 179
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From: Baltimore, MD
Originally Posted by Another_User
A problem I have tuning with the IFR or MAF table is if you are running a modified intake that is throwing you "lean", and it is dumping extra fuel in, but your VE table is running you rich, then you are just creating an even more excessively rich condition whenever the VE table is referenced. Just a thought.
I'm under the impression that as long as the MAF's plugged in, it will use that to determine fueling at part throttle and just add PE at WOT. Where does the VE table come in?
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Originally Posted by squirrels
This is a point of confusion for me...I thought the VE table was only used when the MAF was not functioning properly or was unplugged.
I'm under the impression that as long as the MAF's plugged in, it will use that to determine fueling at part throttle and just add PE at WOT. Where does the VE table come in?
I'm under the impression that as long as the MAF's plugged in, it will use that to determine fueling at part throttle and just add PE at WOT. Where does the VE table come in?
My MAF functions a little differently. Since it is sitting on the table in my garage.
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No, they're both closed loop. Which one is used is RPM dependant (when the MAF is working).
Here's something that Chris posted on the HPTuners forum.
Here's something that Chris posted on the HPTuners forum.
Originally Posted by Chris@HPTuners
RPM > 4000
----------
trust MAF completely and ignore SD calcs (apart from MAF sanity checking purposes)
RPM < 4000
----------
if RPM < 2400 and MAP < 84 kPa then
Steady MAP threshold = 0.0 kPa
else
Steady MAP threshold = 0.8 kPa
If (SteadyMAP) then
Calculate MAFAirmass/SDAirmass ratio (used for Unsteady MAP operation)
Correction Airmass = MAF Airmass (filtered)
else
Correction Airmass = SD Airmass x MAF/SD Airmass Ratio (calculated during Steady MAP conditions)
Transient Corrected Airmass = previous Final Airmass + proportion of Correction Airmass
Final Airmass = fn(MAF Airflow, previous MAF Airflow, prev 3 MAP readings, prev 3 TPS readings,
Transient Corrected Airmass)
----------
trust MAF completely and ignore SD calcs (apart from MAF sanity checking purposes)
RPM < 4000
----------
if RPM < 2400 and MAP < 84 kPa then
Steady MAP threshold = 0.0 kPa
else
Steady MAP threshold = 0.8 kPa
If (SteadyMAP) then
Calculate MAFAirmass/SDAirmass ratio (used for Unsteady MAP operation)
Correction Airmass = MAF Airmass (filtered)
else
Correction Airmass = SD Airmass x MAF/SD Airmass Ratio (calculated during Steady MAP conditions)
Transient Corrected Airmass = previous Final Airmass + proportion of Correction Airmass
Final Airmass = fn(MAF Airflow, previous MAF Airflow, prev 3 MAP readings, prev 3 TPS readings,
Transient Corrected Airmass)
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