rich at WOT 11.5 AFR
09-28-2010, 12:36 AM
#1
rich at WOT 11.5 AFR my mildly modded 99 TA is rich at WOT 11.5 AFR
I have a stock 75MM ported throttle body and stock MAF.
? If I ream out my FAST 78MM intake manifold an use a 85mm throttle body & 85MM mass air meter would this extra air lean out this rich 11.5 WOT AFR
to a more desirable AFR?
Thanks
I have a stock 75MM ported throttle body and stock MAF.
? If I ream out my FAST 78MM intake manifold an use a 85mm throttle body & 85MM mass air meter would this extra air lean out this rich 11.5 WOT AFR
to a more desirable AFR?
Thanks
09-28-2010, 06:58 AM
#2
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Might use the word, "ported" instead of reamed, but no, it will not. The 85mm MAF might make things worse (at least further out of tune) and is certainly not needed for a mildly modded engine.
If you're commanding, say 12.8 at WOT and getting 11.5, you're going to have to get your MAF properly calibrated in order to get the commanded PE.
If you're commanding, say 12.8 at WOT and getting 11.5, you're going to have to get your MAF properly calibrated in order to get the commanded PE.
09-28-2010, 07:35 AM
#3
port actualley the FAST78 has been ported at the intake runners for stock heads
I probably should have worded the opening widened or port matched for a larger TB.
? what about just a 85mm throttle body and stock MAF would this lean it to a more desirable AFR?
also my ported stock 75mm TB do'es not have the bump stop mod (decided against it because I was concerned w/ it sticking wide open)
if I did the bump stop mod so my TB would open 100% would this help lean it out?
Thanks
I probably should have worded the opening widened or port matched for a larger TB.
? what about just a 85mm throttle body and stock MAF would this lean it to a more desirable AFR?
also my ported stock 75mm TB do'es not have the bump stop mod (decided against it because I was concerned w/ it sticking wide open)
if I did the bump stop mod so my TB would open 100% would this help lean it out?
Thanks
09-28-2010, 09:36 AM
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The computer is going to compensate for changes with STFT and LTFTs to get fueling back to stoich during cruise. It's not like the carb. cars with fixed jets. If the car is leaned (more efficient intake, exhaust) it makes the fuel trims positive and those are actually ADDED to whatever PE commands.
In order to get fueling correct at PE, you are going to have to calibrate your MAF.
In order to get fueling correct at PE, you are going to have to calibrate your MAF.
09-28-2010, 10:23 AM
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A factory 85mm MAF will give you a bogus high airflow
reading and put you richer. You can add your own
opposing bogosity like SLP does, and hope for the
best (there's no science for you, from them). To get
the MAF readings right, you'd use a stock 85mm and
a stock MAF table (which one is "rightest", varies with
your setup - are you more "trucky" or "vettey"?). And
you'd accept a lesser ultimate airflow limit. Or stick with
stock and stock, and just clean it.
Your stock tunes command fat WOT fueling. Are you on
a stock tune?
And before you get all eager to change that, do you
have any reason to believe in fundamental airflow
accuracy, VE or MAF? And accuracy in the embedded
assumptions of fuel pressure at the rail?
Wheels within wheels, and odds are some of them are
a bit out of round.
reading and put you richer. You can add your own
opposing bogosity like SLP does, and hope for the
best (there's no science for you, from them). To get
the MAF readings right, you'd use a stock 85mm and
a stock MAF table (which one is "rightest", varies with
your setup - are you more "trucky" or "vettey"?). And
you'd accept a lesser ultimate airflow limit. Or stick with
stock and stock, and just clean it.
Your stock tunes command fat WOT fueling. Are you on
a stock tune?
And before you get all eager to change that, do you
have any reason to believe in fundamental airflow
accuracy, VE or MAF? And accuracy in the embedded
assumptions of fuel pressure at the rail?
Wheels within wheels, and odds are some of them are
a bit out of round.
09-29-2010, 07:20 AM
#6
MAF calibration The computer is going to compensate for changes with STFT and LTFTs to get fueling back to stoich during cruise. It's not like the carb. cars with fixed jets. If the car is leaned (more efficient intake, exhaust) it makes the fuel trims positive and those are actually ADDED to whatever PE commands.
In order to get fueling correct at PE, you are going to have to calibrate your MAF.
In order to get fueling correct at PE, you are going to have to calibrate your MAF.
Thanks for advice
A factory 85mm MAF will give you a bogus high airflow
reading and put you richer. You can add your own
opposing bogosity like SLP does, and hope for the
best (there's no science for you, from them). To get
the MAF readings right, you'd use a stock 85mm and
a stock MAF table (which one is "rightest", varies with
your setup - are you more "trucky" or "vettey"?). And
you'd accept a lesser ultimate airflow limit. Or stick with
stock and stock, and just clean it.
Your stock tunes command fat WOT fueling. Are you on
a stock tune?I did observe this Fat condition during WOT runs w/ stock tune
w/ only a narrow band.
car has been tuned about 5 years ago w/ HP tuners (by a novis) first time he tuned it the narrow band read only one green light of richness car ran great.
he had to come back and redo the delete on the rear o2 sensors He forgot to delete them in the initial tune. he then stated he wanted to richen it up a bit
for safety so after the 2nd tune I had 3 green lights of richness on the narrow band.
after the 2nd tune I kindof lost interest and just enjoyed what I had.
don't misunderstand me the car runs great gets expected fuel milage ect.
was concerned w/ stuff like the smeal of gas & I was told about all this extra fuel been a bad condition washing out the cylinder walls & not enought spark to burn the extra fuel also at the 11.5 it was pulling 2 degrees of timing I'm thinking this is where I'm losing a tad bit of power.? about how much power is lost w/ 2 degrees of timing being pulled by the ECM?
I now have a wide band and it reads 11.5 AFR at WOT
so the car has been like this for a long while.
Thanks Jimmie
And before you get all eager to change that, do you
have any reason to believe in fundamental airflow
accuracy, VE or MAF? And accuracy in the embedded
assumptions of fuel pressure at the rail?
Wheels within wheels, and odds are some of them are
a bit out of round.
reading and put you richer. You can add your own
opposing bogosity like SLP does, and hope for the
best (there's no science for you, from them). To get
the MAF readings right, you'd use a stock 85mm and
a stock MAF table (which one is "rightest", varies with
your setup - are you more "trucky" or "vettey"?). And
you'd accept a lesser ultimate airflow limit. Or stick with
stock and stock, and just clean it.
Your stock tunes command fat WOT fueling. Are you on
a stock tune?I did observe this Fat condition during WOT runs w/ stock tune
w/ only a narrow band.
car has been tuned about 5 years ago w/ HP tuners (by a novis) first time he tuned it the narrow band read only one green light of richness car ran great.
he had to come back and redo the delete on the rear o2 sensors He forgot to delete them in the initial tune. he then stated he wanted to richen it up a bit
for safety so after the 2nd tune I had 3 green lights of richness on the narrow band.
after the 2nd tune I kindof lost interest and just enjoyed what I had.
don't misunderstand me the car runs great gets expected fuel milage ect.
was concerned w/ stuff like the smeal of gas & I was told about all this extra fuel been a bad condition washing out the cylinder walls & not enought spark to burn the extra fuel also at the 11.5 it was pulling 2 degrees of timing I'm thinking this is where I'm losing a tad bit of power.? about how much power is lost w/ 2 degrees of timing being pulled by the ECM?
I now have a wide band and it reads 11.5 AFR at WOT
so the car has been like this for a long while.
Thanks Jimmie
And before you get all eager to change that, do you
have any reason to believe in fundamental airflow
accuracy, VE or MAF? And accuracy in the embedded
assumptions of fuel pressure at the rail?
Wheels within wheels, and odds are some of them are
a bit out of round.
Last edited by badmfkr; 09-29-2010 at 07:27 AM.
09-29-2010, 01:01 PM
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No; it is a very simple process, but must be done on the car to be exactly matched to your car and its mods. if you haven't changed a lot in the intake track, you may be ok. I'd have someone look at your PE table. As mentioned, it is probably pretty rich from the factory.
Most guys (tuners??) would just adjust the PE table to arrive at the correct AFR, but I'm just advising the correct way, which would be to correct the MAF fueling signal, INSTEAD of hacking the PE.
No more than you're modded, it shouldn't be a major issue
Most guys (tuners??) would just adjust the PE table to arrive at the correct AFR, but I'm just advising the correct way, which would be to correct the MAF fueling signal, INSTEAD of hacking the PE.
No more than you're modded, it shouldn't be a major issue
