Tuning Virgin
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Teching In
Joined: Dec 2004
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Tuning Virgin I'm a tuning virgin. I'm trading my wrenches in for a labtop. I know I got a lot to learn, but get me started. My 04 GTO M6 is stock and plan to keep it that way for a short while. What does my tuning starter kit look like and what do I do without heavy mods to tune the car to run faster?
It's still air, fuel and spark when you get to the bottom
of it all.
With a stock car you're basically looking to discover and
eliminate all of the conservatism / stupidity that GM put
into it. You want logging and tuning capability. Ideally,
access to a wideband O2 meter as well (this is a good tool
to borrow rather than buy unless you're a persistent and
compulsive modder). You want to know that engine base tune is
correct and stable. This means logging, looking at fuel trims
(the engine's "status report" on how accurate the stock tune
is, at least in closed loop, for air metering and fuel delivery.
Stock, you should be pretty tight and accurate. It's best to
try and keep returning to stock-like accuracy as you modify
the car, before a lot of little error sources stack up into a
big yarn-ball.
You want to make high-throttle fuel delivery optimal for
torque (midband) and power (top end). This likely means
changing GM's power enrichment (PE) vs RPM curve, at
least if your car is as detuned / mistuned in that respect.
If your base tune is accurate then simply changing the
PE table to a calculated ideal (like 14/7/12.8=1.15)
value is a good first guess. Here's where you want the
feedback from a WBO2 meter, because what you set is
not to be trusted, to be what you get. Fatter at midband
might improve your torque, leaner up top might improve
power, these you'd want to have feedback from track or
dyno or G-meter etc.
Setting proper fueling can bump against other engine
realities - coolant temp, cold air induction or lack,
degree of exhaust restriction all factor in. The engine
temps are PCM controlled in a car with electric fans.
make it consistent by putting fan temp at or below the
thermostat pivot temp (if you don't mind the constant
drone).
Spark is also something where GM tends to leave a lot
on the table. Set it after you think you have fuel and
other things sorted. Spark and fuel interplay a fair bit
but I think there's no point in dumping excess fuel to let
you have more spark advance. Spark retard effects are
also a big part of tuning on this series of engine. Knock
retard tends to be applied heavy and released slow; it
comes in a lot at tip-in if you have any lean error in the
speed-density side of the tune (VE table). Messing VE around
is probably best left for later unless you find a lot of tip-in
ping. Reducing KR attack and increasing decay can improve
power in the seconds after tip-in. You don't want to totally
squash **** protection but settle it down. Check that your
PE enable thresholds (TPS, MAP) are not so high that these
hold off enrichment until after you start to ping. You want
to know that burst knock retard is not being applied except
(perhaps) on fast throttle events; less a concern for cars than
trucks where the BK is a bit too busy.
HPTuners is my tool of choice for logging & tuning. I have an
Innovate LM-1 wideband O2 meter and a G-Tech meter (though
I use that only rarely; it's a convenient way to measure your
acceleration, however you can do the same with the logger,
in a fashion, with the VSS speed numbers and timestamps).
But I didn't trade in my wrenches; they have plenty of uses left.
Ever try installing new suspension pieces with a touchpad?
of it all.
With a stock car you're basically looking to discover and
eliminate all of the conservatism / stupidity that GM put
into it. You want logging and tuning capability. Ideally,
access to a wideband O2 meter as well (this is a good tool
to borrow rather than buy unless you're a persistent and
compulsive modder). You want to know that engine base tune is
correct and stable. This means logging, looking at fuel trims
(the engine's "status report" on how accurate the stock tune
is, at least in closed loop, for air metering and fuel delivery.
Stock, you should be pretty tight and accurate. It's best to
try and keep returning to stock-like accuracy as you modify
the car, before a lot of little error sources stack up into a
big yarn-ball.
You want to make high-throttle fuel delivery optimal for
torque (midband) and power (top end). This likely means
changing GM's power enrichment (PE) vs RPM curve, at
least if your car is as detuned / mistuned in that respect.
If your base tune is accurate then simply changing the
PE table to a calculated ideal (like 14/7/12.8=1.15)
value is a good first guess. Here's where you want the
feedback from a WBO2 meter, because what you set is
not to be trusted, to be what you get. Fatter at midband
might improve your torque, leaner up top might improve
power, these you'd want to have feedback from track or
dyno or G-meter etc.
Setting proper fueling can bump against other engine
realities - coolant temp, cold air induction or lack,
degree of exhaust restriction all factor in. The engine
temps are PCM controlled in a car with electric fans.
make it consistent by putting fan temp at or below the
thermostat pivot temp (if you don't mind the constant
drone).
Spark is also something where GM tends to leave a lot
on the table. Set it after you think you have fuel and
other things sorted. Spark and fuel interplay a fair bit
but I think there's no point in dumping excess fuel to let
you have more spark advance. Spark retard effects are
also a big part of tuning on this series of engine. Knock
retard tends to be applied heavy and released slow; it
comes in a lot at tip-in if you have any lean error in the
speed-density side of the tune (VE table). Messing VE around
is probably best left for later unless you find a lot of tip-in
ping. Reducing KR attack and increasing decay can improve
power in the seconds after tip-in. You don't want to totally
squash **** protection but settle it down. Check that your
PE enable thresholds (TPS, MAP) are not so high that these
hold off enrichment until after you start to ping. You want
to know that burst knock retard is not being applied except
(perhaps) on fast throttle events; less a concern for cars than
trucks where the BK is a bit too busy.
HPTuners is my tool of choice for logging & tuning. I have an
Innovate LM-1 wideband O2 meter and a G-Tech meter (though
I use that only rarely; it's a convenient way to measure your
acceleration, however you can do the same with the logger,
in a fashion, with the VSS speed numbers and timestamps).
But I didn't trade in my wrenches; they have plenty of uses left.
Ever try installing new suspension pieces with a touchpad?
