HELP No idea where to start.
04-04-2005, 07:09 PM
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HELP No idea where to start. I'm currentley in the process of installing a patriot heads and cam package on my '98 T/A. I have installed A pair of Hooker LT headers, SLP air box lid, Slp MAF ,Hooker Y pipe, and slp loudmouth exhaust. I have a stock ls1 intake manifold and a ligenfelter all aluminum intake that i have begun porting, along with a BBK throttle body. What intake should i use? I've thought about the LSX but i dont have the $ right now. The real question is where do I start with the Tuneing for the heads and cam? I was originally thinking about buying LS1 Edit but after reading around LS1Tech I heard about HPtuners program. I'm pretty sure im going to go with HP tuners. After I choose a program i really have no idea where to start with the tuning. I'm just looking for any advice or a point in the right direction. Thanks.
04-04-2005, 07:44 PM
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I like HPTuners. First off you will want to go shopping
(on Horist's repository web site) and pull down .bin
files from cars with similar mods to yours. Those will
be good "cheat sheets" to get started.
Save yourself some degree of aggravation and put
the Corvette rear O2s on those headers before you
start to tune. Forget any extensions. These hotter
O2s should either work fine, or be less of a tuning
headache at the least, with the cooler exhaust.
You would be better off taking the resistor out of
the SLP MAF and then inserting a truck MAF table
into your program. That way it's represented as it
is, not a stock table trying to represent a truck MAF
with a resistor on it.
To first order the intake doesn't matter. However,
losing the EGR does. You will want to turn off the
EGR function and the EGR fault codes, and zero the
spark table and any fuel-related EGR adders you can
find (I do not have this stuff on my '02 so can't say
about all the details, but you want to ream it out).
You might be better off to start it off with the LS1
as-was, get it good, remove the EGR, get that done,
and then swap intakes. Some of the aluminum intakes
were prone to lakage problems early on and just on
the chance that you have these sorts of troubles, it
sure would be nice to not be fighting a vacuum leak
on top of all the other changed stuff.
The headers are going to raise your volumetric efficiency
midband to top end. The cam will raise it up top and
lower it near idle. Big cams can really whack the idle
mixture in a couple of ways. Reversion and simple loss
of pumping efficiency make it so you pump less air than
the speed density tune believes from the stock table.
That puts you rich, makes the idle control loop soggy
and prone to overshoot, undershoot, or oscillate (both
forever and ever, amen). Then, the lower efficiency
raises the idle MAP. When cold this indexes you up in
the open loop fuel air table and takes you from rich
straight to pig-rich. You will be playing with the idle RPM
and airflow first, just to get it to stay alive, and then
work over the lower end of the VE table to get the hot
idle nice and tight, then shave back the OLFA table
for cold start / warmup in the areas near your new
idle MAP. The upper end of the VE table you will want
to raise a fair bit. My preference is to use the in-car
O2s and your knock retard as the guides. You can
also try straight speed-density tuning but to do that
at WOT you really need a wideband. To do without it,
you would be wanting to do a bunch of 3/4-throttle to
WOT blips from different RPM and look at how the O2s
react. 3/4 throttle should be well into PE. If you see
the O2 voltage dip then your SD tune is leaner than
the MAF tune (or more correctly the SD calculated
airflow is less than the MAF calculated air). Given that
you have a trustworthy MAF, which a truck MAF is and
an SLP is not, up top, the SD tune can be tweaked up
to match the MAF at the spots you have observation,
and smoothed in around it. I have used the KR for the
lower-throttle, tip-in knock to guide me to a not-too-
lean VE table in the midband.
You would like to borrow a wideband unit one time to
tune PE/WOT mixture. The in-car O2s can tell you about
closed loop / 14.7:1 operation, and they can tell you
about relative mixture like throttle tip-in but they are
no good for high enrichment like you want at WOT. The
stock PE table is too fat. If you had truth from all of
your sensors and a properly modeled fuel shot you would
like about 1.15 for the PE table instead of 1.25 (A/F =
14.7 / FAM). FAM being fuel air multiplier which is how
all the tables having to do with enrichment are done.
But again, too many changes to go in trusting.
(on Horist's repository web site) and pull down .bin
files from cars with similar mods to yours. Those will
be good "cheat sheets" to get started.
Save yourself some degree of aggravation and put
the Corvette rear O2s on those headers before you
start to tune. Forget any extensions. These hotter
O2s should either work fine, or be less of a tuning
headache at the least, with the cooler exhaust.
You would be better off taking the resistor out of
the SLP MAF and then inserting a truck MAF table
into your program. That way it's represented as it
is, not a stock table trying to represent a truck MAF
with a resistor on it.
To first order the intake doesn't matter. However,
losing the EGR does. You will want to turn off the
EGR function and the EGR fault codes, and zero the
spark table and any fuel-related EGR adders you can
find (I do not have this stuff on my '02 so can't say
about all the details, but you want to ream it out).
You might be better off to start it off with the LS1
as-was, get it good, remove the EGR, get that done,
and then swap intakes. Some of the aluminum intakes
were prone to lakage problems early on and just on
the chance that you have these sorts of troubles, it
sure would be nice to not be fighting a vacuum leak
on top of all the other changed stuff.
The headers are going to raise your volumetric efficiency
midband to top end. The cam will raise it up top and
lower it near idle. Big cams can really whack the idle
mixture in a couple of ways. Reversion and simple loss
of pumping efficiency make it so you pump less air than
the speed density tune believes from the stock table.
That puts you rich, makes the idle control loop soggy
and prone to overshoot, undershoot, or oscillate (both
forever and ever, amen). Then, the lower efficiency
raises the idle MAP. When cold this indexes you up in
the open loop fuel air table and takes you from rich
straight to pig-rich. You will be playing with the idle RPM
and airflow first, just to get it to stay alive, and then
work over the lower end of the VE table to get the hot
idle nice and tight, then shave back the OLFA table
for cold start / warmup in the areas near your new
idle MAP. The upper end of the VE table you will want
to raise a fair bit. My preference is to use the in-car
O2s and your knock retard as the guides. You can
also try straight speed-density tuning but to do that
at WOT you really need a wideband. To do without it,
you would be wanting to do a bunch of 3/4-throttle to
WOT blips from different RPM and look at how the O2s
react. 3/4 throttle should be well into PE. If you see
the O2 voltage dip then your SD tune is leaner than
the MAF tune (or more correctly the SD calculated
airflow is less than the MAF calculated air). Given that
you have a trustworthy MAF, which a truck MAF is and
an SLP is not, up top, the SD tune can be tweaked up
to match the MAF at the spots you have observation,
and smoothed in around it. I have used the KR for the
lower-throttle, tip-in knock to guide me to a not-too-
lean VE table in the midband.
You would like to borrow a wideband unit one time to
tune PE/WOT mixture. The in-car O2s can tell you about
closed loop / 14.7:1 operation, and they can tell you
about relative mixture like throttle tip-in but they are
no good for high enrichment like you want at WOT. The
stock PE table is too fat. If you had truth from all of
your sensors and a properly modeled fuel shot you would
like about 1.15 for the PE table instead of 1.25 (A/F =
14.7 / FAM). FAM being fuel air multiplier which is how
all the tables having to do with enrichment are done.
But again, too many changes to go in trusting.
