Granatelli MAF screwing me up a little? if so, will LS1edit dyno tune definitely fix?
10-19-2004, 08:25 AM
#1
TECH Resident
Thread Starter
iTrader: (6)
Join Date: Oct 2004
Location: Long island, NY
Posts: 947
Likes: 0
Received 0 Likes
on
0 Posts
Granatelli MAF screwing me up a little? if so, will LS1edit dyno tune definitely fix? Recently got my car dynoed @ TTP in NJ and I was a dissapointed in the numbers: 315rwhp/326 Tq.
Most people have said the #'s seem about right but a couple others have agreed they look a little low.
A few people suggested that the GMAF is probably screwing me up. However, I am told that the dyno sheet A/F looks good. So could the GMAF still be screwing me up independent of the decent A/F reading on the dyno sheet??
My car: 99 WS6 M6
power mods:
MTI lid
JBA shorties (I know these add very little if anything)
SLP LM w/Borla XR-1 mufflers
Shaner S2 ported TB
Brian Greene Ram air (won't do anything on dyno obviously).
stock rear/gears
Have 17X11 Boyds w/315's out back which may rob a little power.
Here is the dyno sheet:
Now I am in the process of adding LT's & orp and an LS6 intake and eventually a 224/224 cam and I am also wondering if the more mods I add the more I should be concerned about the GMAF screwing me up. After the cam goes in, and maybe even after the LT's and orp goes in, I plan on having the car dyno tuned w/LS1edit. Initially I assumed any problems the GMAF might introduce would be fixed by a good dyno tune and than I would even benefit from it being that it should flow better than the stock one...but I am not so sure. Should I look into putting a stock one back in (I don't have the original stock one-I'd have to get a different one), or is it not worth it to even bother swapping back to stock b/c again the dyno tune would cancel any problems possible introduced by the GMAF??
PS- Just for the record and as a side note, the GMAF was on the car when I bought it. The original owner said at first the car was pinging with it and he had to send it back to Granatelli for them to recalibrate it, and after he got it back he said the car was great. The only power mod I have personally added so far was the ported TB. Maybe that was enough to throw things back off??
Thanks,
Kevin
Most people have said the #'s seem about right but a couple others have agreed they look a little low.
A few people suggested that the GMAF is probably screwing me up. However, I am told that the dyno sheet A/F looks good. So could the GMAF still be screwing me up independent of the decent A/F reading on the dyno sheet??
My car: 99 WS6 M6
power mods:
MTI lid
JBA shorties (I know these add very little if anything)
SLP LM w/Borla XR-1 mufflers
Shaner S2 ported TB
Brian Greene Ram air (won't do anything on dyno obviously).
stock rear/gears
Have 17X11 Boyds w/315's out back which may rob a little power.
Here is the dyno sheet:
Now I am in the process of adding LT's & orp and an LS6 intake and eventually a 224/224 cam and I am also wondering if the more mods I add the more I should be concerned about the GMAF screwing me up. After the cam goes in, and maybe even after the LT's and orp goes in, I plan on having the car dyno tuned w/LS1edit. Initially I assumed any problems the GMAF might introduce would be fixed by a good dyno tune and than I would even benefit from it being that it should flow better than the stock one...but I am not so sure. Should I look into putting a stock one back in (I don't have the original stock one-I'd have to get a different one), or is it not worth it to even bother swapping back to stock b/c again the dyno tune would cancel any problems possible introduced by the GMAF??
PS- Just for the record and as a side note, the GMAF was on the car when I bought it. The original owner said at first the car was pinging with it and he had to send it back to Granatelli for them to recalibrate it, and after he got it back he said the car was great. The only power mod I have personally added so far was the ported TB. Maybe that was enough to throw things back off??
Thanks,
Kevin
10-19-2004, 09:16 AM
#2
Moderator
iTrader: (11)
Join Date: Mar 2002
Location: East Central Florida
Posts: 12,605
Likes: 0
Received 6 Likes
on
6 Posts
The GMAF only screws you up if the MAF table is not
made to produce true mass airflow values from it. Your
wideband O2 line looks pretty reasonable. Ported TB
will not affect mixture unless it's leaking.
The problem is, people put a GMAF on and expect it to
help them without tuning and in general, it hurts instead.
Check with your tuner and verify that they did the right
thing (a GMAF-proper MAF table) rather than some sort
of fakery (like adjusting the injector table instead). If
they did it proper, then you're set I reckon and going back
would be more work. If they hoaxed it to get the right
result by offsetting errors, instead of eliminating errors,
then going back to stock MAF would make it simpler to
get proper. But the result looks OK. Maybe just a tad
chubby but call that safety margin.
I would just go ahead and hang on the stuff you have
going and go back to the tune (the cam and headers
will make you need it anyway), check that the AFR line
is staying where it belongs and push timing until you
can take no more.
made to produce true mass airflow values from it. Your
wideband O2 line looks pretty reasonable. Ported TB
will not affect mixture unless it's leaking.
The problem is, people put a GMAF on and expect it to
help them without tuning and in general, it hurts instead.
Check with your tuner and verify that they did the right
thing (a GMAF-proper MAF table) rather than some sort
of fakery (like adjusting the injector table instead). If
they did it proper, then you're set I reckon and going back
would be more work. If they hoaxed it to get the right
result by offsetting errors, instead of eliminating errors,
then going back to stock MAF would make it simpler to
get proper. But the result looks OK. Maybe just a tad
chubby but call that safety margin.
I would just go ahead and hang on the stuff you have
going and go back to the tune (the cam and headers
will make you need it anyway), check that the AFR line
is staying where it belongs and push timing until you
can take no more.
10-19-2004, 10:46 AM
#3
TECH Resident
Thread Starter
iTrader: (6)
Join Date: Oct 2004
Location: Long island, NY
Posts: 947
Likes: 0
Received 0 Likes
on
0 Posts
The GMAF only screws you up if the MAF table is not
made to produce true mass airflow values from it.
made to produce true mass airflow values from it.
owner of the car bought it from them new and than sent it back to
them for the recalibration after he was experiencing pinging.
Do you think, or have you ever heard cases where they (Granatelli)
have calibrarted it in such a way that the MAF table is not made to
produce true massairflow values?
The problem is, people put a GMAF on and expect it to
help them without tuning and in general, it hurts instead.
Check with your tuner and verify that they did the right
thing (a GMAF-proper MAF table) rather than some sort
of fakery (like adjusting the injector table instead).
help them without tuning and in general, it hurts instead.
Check with your tuner and verify that they did the right
thing (a GMAF-proper MAF table) rather than some sort
of fakery (like adjusting the injector table instead).
do some sort of fakery calibration, but i think what you are
saying is to have my tuner check to make sure that granatelli
didn't do the fakery when they recalibrated it. So the tuner will
definitely be able to figure out whether they did or not?
If they did it proper, then you're set I reckon and going back
would be more work. If they hoaxed it to get the right
result by offsetting errors, instead of eliminating errors,
then going back to stock MAF would make it simpler to
get proper. But the result looks OK. Maybe just a tad
chubby but call that safety margin.
would be more work. If they hoaxed it to get the right
result by offsetting errors, instead of eliminating errors,
then going back to stock MAF would make it simpler to
get proper. But the result looks OK. Maybe just a tad
chubby but call that safety margin.
can't just simply fix it with some LS1edit tuning/tweaking?
So are you saying that the GMAF would actually have to
be pulled back out and physically recalibrated if they did
hoax it?? (In which case I'd probably be better off just
putting a stock one back in).
And finally, would you agree as long as the MAF is calibrated properly and the car is tuned that this unit should add a little extra power over the stocker? I mean it should flow better shouldnt it? Or is the GMAF just one big BS hoax that adds no power even when properly calibrated and tuned...
10-20-2004, 06:58 AM
#6
TECH Resident
Thread Starter
iTrader: (6)
Join Date: Oct 2004
Location: Long island, NY
Posts: 947
Likes: 0
Received 0 Likes
on
0 Posts
I would if it was already in there, but I am wondering since the GMAF is already in there, if a dyno tune would clear up any thing the GMAF might be screwing up, in which case it would be pointless for me to swap it out (since I will be getting a dyno tune anyway after I add cam).
10-20-2004, 08:33 AM
#7
Moderator
iTrader: (11)
Join Date: Mar 2002
Location: East Central Florida
Posts: 12,605
Likes: 0
Received 6 Likes
on
6 Posts
With the GMAF being re-recalibrated there is really no telling
what its actual effects are, relative to the as-shipped GMAFs
(which are known to be bad news). If the AFR line you show
is not the result of tuning, then the GMAF is in fact leaning
the car out (as is its intent) because stock tune commands
a fat PE (11.76 by 14.7/1.250 PE table) and you are showing
a 12.7ish result. To get that happy bolt-on result you are
using a MAF that is throwing bogus airflow data (low) and
the secondary effects can hurt you. They can also be tuned
away ("Yes" to part B of the original question). But, the GMAF
is an unknown. Granatelli won't tell anybody what the true
calibration table for that unit is. Maybe they don't know or
maybe they're afraid that once their highly valuable false
calibration secret is known, they will have to share the market
for over-hyped trouble-causing MAFs. Heh.
As a rough guide you could take that 11.76 (ideal) divided by
the wideband 12.7(ish) and go scale the MAF table by the
indicated 1.08, and then see if putting your PR table to 1.150
(commanding 12.8:1) puts you back to proper AFR without
other side effects (mainly timing and A4 transmission) and
then get your timing adjusted tight for sporty.
But that's all just extra work to accommodate the GMAF and
your tuner would almost surely prefer to be dealing with as
little non-standard-calibration stuff as possible. You could
spend a bunch of time in cut-and-try tuning for the MAF to
be sub-percent proper, and if time is money, well, ....
But if you don't -have- a stock MAF handy, maybe you just
want to work through it.
what its actual effects are, relative to the as-shipped GMAFs
(which are known to be bad news). If the AFR line you show
is not the result of tuning, then the GMAF is in fact leaning
the car out (as is its intent) because stock tune commands
a fat PE (11.76 by 14.7/1.250 PE table) and you are showing
a 12.7ish result. To get that happy bolt-on result you are
using a MAF that is throwing bogus airflow data (low) and
the secondary effects can hurt you. They can also be tuned
away ("Yes" to part B of the original question). But, the GMAF
is an unknown. Granatelli won't tell anybody what the true
calibration table for that unit is. Maybe they don't know or
maybe they're afraid that once their highly valuable false
calibration secret is known, they will have to share the market
for over-hyped trouble-causing MAFs. Heh.
As a rough guide you could take that 11.76 (ideal) divided by
the wideband 12.7(ish) and go scale the MAF table by the
indicated 1.08, and then see if putting your PR table to 1.150
(commanding 12.8:1) puts you back to proper AFR without
other side effects (mainly timing and A4 transmission) and
then get your timing adjusted tight for sporty.
But that's all just extra work to accommodate the GMAF and
your tuner would almost surely prefer to be dealing with as
little non-standard-calibration stuff as possible. You could
spend a bunch of time in cut-and-try tuning for the MAF to
be sub-percent proper, and if time is money, well, ....
But if you don't -have- a stock MAF handy, maybe you just
want to work through it.
