HOW TO TUNE AN ENGINE THE RIGHT WAY... by Jeff Schaefer
#1 Proper Break-In. Refer to break-in article HERE.
#2 What do I need to tune a car effectively?
Good question Jeff, glad you asked that! lol. Here is a list of what
-A Dyno of any kind, preferably DynoJet or Dynapack. There are positives
to both, but I am going to have to give the nod to the dynapack for a few
reasons. The primary reason is that it is much easier to tune a car for
light, normal driving on it, and much more precise. For full throttle,
they are both equal. Sure, the Dynapack is a few times more accurate, but
when your talking 1/10 of 1 HP, who cares. So if you have a dynapack in
your area, use that, you will get better drivability daily out of tuning from
-Second thing your going to need to tune a car is a second person. This
person is your go-to guy, so to speak. He stays outside the car and takes
orders from the guy inside the car with the laptop. He is also an
observer, and can spot any potential problems, like a loose timing belt, that
the guy in the car has no clue about. He is also useful to adjust timing
on the car, while the tuner inside the car with the laptop gets the car to idle
properly. He can also adjust fuel pressure to the desired level the tuner
inside the car wishes. He can spot fuel leaks the tuner cannot see.
In other words, its a 2 man effort to do it completely perfect. Otherwise,
your running in and out of the car all the time. One thing the 2nd person
should not do is relay information about the graph to the tuner. The tuner
should look at the graph, in person to determine the next changes to be made.
-The third thing you will need is a Wideband 02 sensor hooked up to the car,
either deep into the tailpipe, or screwed into an 02 bung BEFORE the cat.
You want to make sure its screwed in right before the cat, and not say, 6 inches
out of the head in the primary header part. At that point, it is only
reading 1 cylinder, not a combination of all 4, which is what we desire.
-You may also need a clip board, with a blank piece of paper to take notes on.
I will talk about this later.
-Bring an extra set of spark plugs, a gapper, and a tool to remove and install
spark plugs with you.
-Always bring 1-2 extra quarts of oil.
-Bring ear protection in most cases for cars with no cat, or muffler.
You are now ready to tune a car. lets get started.
I am going to be speaking to you all in regards to a Hondata unit, but no matter
what unit you use, its all similar.
Step 1: Put the Wideband on the car, before you start it.
Do that, then hook up your laptop and start up the car. Immediately look
at the air/fuel ratio the car is warming up at. When the car is warming
up, it will tend to be a little rich, like in the 13's:1 air fuel ratio.
When the car gets past a certain temperature, like when the temp gauge starts to
move past the first line, the car should have an air/fuel ratio of 14.7:1.
This is a number you need to memorize. 14.7:1. During idle, and all
normal driving under 50% throttle, you want 14.7:1 air fuel ratio. What
does under 50% throttle mean? People ask me that. It means that in
the tables your ECU is programmed with, your half way up the table, so if the
table has 10 columns, your in column 5. Look at this illustration below.
Notice I have it showing a row for vacuum, and above that the rows 1-10, 1 being
no throttle, to 10 being full throttle. Your car will idle in 1-2.
or it should.
See that blue highlighted area on the upper left of the matrix, that's when I
am datalogging it is showing me exactly where in the matrix I am at while
driving. At this case, its bouncing back and forth between columns 1 and
2, at idle, at around 750-800 RPM. Notice that the proper air/fuel ratio
up to 50% throttle is 14.7. This is going to get you maximum fuel economy.
Now you are NOT going to change the numbers in the matrix to change the air/fuel
ratio to get the car to idle at 14.7. Not yet. First your going to
rev the car up and down to like 3k, with slight throttle to see if the numbers
are consistent. Say, your idling at 14.7 then you give it a little
throttle and your at 12:1, thats not normal and going to need attention.
If your satisfied the numbers are consistent then go ahead and adjust the
INJECTOR MULTIPLIER until your near 14.7, and when you rev up and down a little,
the numbers are consistent around what your shooting for. Otherwise, your
just going to need massive changes all over your matrix, and your making more
work for yourself. Most often, then not, on most motors, when your idling
at 14.7, the rest of the matrix up to 50% throttle won't be horribly off.
It could be 13.xx, or 16.xx but that's ok, we can fix that later. I am talking
about going from 14.7 to like 11:1, or 19:1... So now we have the car idling at
around 800 RPM, and its got an air/fuel ratio of 14.7:1. Now you call on
your boy out there standing over the motor to check the timing. You want
to set the timing at stock, which is 16 degrees, at 800 RPM. Make sure the
cam gear that controls the timing, like on a B series motors its the intake cam
gear, is set at 0. Now adjust your distributor until your at 16 degrees.
Great, now check in your Hondata to make sure its BASE timing in the settings is
16 degrees, here is how to do that:
File-->Settings-->Vehicle tab---> Make sure its 16, and then hit
OK. This is critical. You see, don't make the mistake of a
rookie tuner by having the number in the Hondata different than the number on
the distributor. Talk about confusing. Don't even think about
starting without 16, and 16, I don't care who tells you otherwise. turbo,
NOS, whatever, your doing it that way! DO IT! Because what these
rookies didn't think of is that 99% of the time your driving around in less than
50% throttle and the reduction in timing due to the NOS, or Turbo, or Blower are
not going to be needed until columns 6-10, for when your giving it alot of
throttle. If you make the timing anything different than 16 in the
Hondata, or on your distributor, your effectively throwing off your entire
matrix of numbers. We want the numbers to stand for exactly what they came
from the factory, at Honda, and go from there.
Ok, now we have the air/fuel ratio at 14.7:1 at idle, and we have the timing
at 16 degrees. That's excellent. Remember when i told you to rev it
up and down a little before going to check the timing was at 16 degrees?
Well now our work has paid off, and we are going to start to drive the car...Put
the car in first gear and ease into it at a very low RPM, like 1500 or 2000.
Drive it slowly up to like 3500 RPM and take note of the air/fuel ratio at light
throttle up to 3500 RPM, if you did the first exercise right with the injector
multiplier, your probably in the ballpark. Drive the car in say, 3rd gear,
from like 1800 RPM to like 3500 RPM and try to hit all the columns between 2 and
6. This is your fuel economy area and attention must be paid to this area.
If you are on a Dynapack, your going to have an easy time at this. Because
you can lock in the computer at say 1750 RPM, and then you can give it throttle
up to column 5 or so and it will stay at that RPM the entire way. So you
just do it slowly, and deliberate, and make changes so your air/fuel is 14.7 up
to column 5. Columns 6 will be 13.5:1 so just hit that column and stop
there....making that last column 13.5:1.
then you do the same for 2000 RPM
then you do the same for 2250 RPM
then you do the same for 2500 RPM
then you do the same for 2700 RPM
then you do the same for 3000 RPM, you get the idea...you look at the Hondata
program, and see what exact RPM, it has numbers you can change. And you
tune to that exact RPM. Every other RPM in between is extrapolated from
the last RPM and the current...so you want to be as accurate as possible and
tune for the exact RPM's the unit you have displays.
Well pretty soon, your engine is loving it and your sitting pretty at 14.7 all
the way up to column 5 at any cruising RPM. Say before 6k. Now take
note of the cars responsiveness under these light throttle activities.
When you give it a little gas, does the car feel responsive? If it does
not you may require slightly more timing in these areas. Try adding like 2
degrees in areas you feel like it was not responsive, and see if it makes a
difference. If it makes no difference, go back to the lower timing.
If you put the timing up to high, and have a blower, or a turbo, and say its
very hot outside, you might start detonating at light throttle under harsh
conditions. so be conservative.
Notice that the entire procedure so far, is pretty much what I stated in
the break-in article? The previous steps of setting idle, timing and
narrow throttle tuning SHOULD BE DONE before you drive that car 100 feet!
After you do all that, you can drive it around if you want to before you tune
for full throttle. Or you can do like us, and just go for it that very day
with like only 20-40 miles on the motor. After taking apart alot of motors
broken in like this, with the pistons looking brand new and so good you could
almost put them back in the box and re-sell them, we are sticking to it.
Some famous motorsycle guys do it this way too, as do professional racing teams.
before we move on, its important to look at the matrix your working with to
make sure its pretty linear. Meaning it is consistent and not jagged, or
you have any numbers in column 2, say, higher in value than column 3! Look
at this example, see how each column 1-10 is right below the others in unison?
And that its fairly flat across the band not all jagged?
If it was all jagged, with the 2nd line from the bottom (which is column 2)
touching column 3, or even column 1, this will be an area your ride is probably
not smooth, or it hesitates. hesitation is usually the result of going
from an area too lean/rich to an area of too rich/lean. Your motor wants a
We now set VTEC. In the Rom Editor, you should be on tab
"Ignition & Fuel Tables" as shown in the picture above. You
might be looking at the matrix view of the graph, because the picture above is
looking at the 2D graph. Anyway, click on the tab to the right of the tab
your on, called "VTEC". Click "FIXED VTEC POINT" and
make sure that box is checked, then go into that area and type in a number you
think is lower than where VTEC might be. Like say, with JUN cams, VTEC
might end up near 6000 RPM, like Toda cams, which are even higher than that.
But we are going to take out the guesswork by using a shortcut to find VTEC in a
hurry. We are going to set VTEC like at 5000 RPM and get ready for the
Time for a test pass!
*Turbo/NOS/Blower your going to want to gradually lower the timing from column 7
on to into boost. Hondata tables are already reduced in timing, but reduce
them some more for safety sake, and then when your tuning bring them back up
**REMEMBER THE AIR INTAKE TEMPERATURE MUST BE EXACTLY THE SAME EVERY SINGLE
PASS. Keep the water temperature consistent also. That
affects fuel at a certain point...so if your dynoing at 180 degrees water, and
100 degrees air, try and keep that every pass. Whatever the car is
comfortable with. If you find yourself waiting 10 minutes between each
pass, your not dynoing at the cars normal temperature and doing it wrong.
The wait should be a few minutes at most, unless its very hot outside. And
you must start at the same exact RPM each time, when you floor it.
Consistency is key in tuning. Ok, now your ready to give it a little
throttle. Go to like 2000 RPM and floor it...keep your eye right on the
lambda meter, and keep your ears open for detonation. At full throttle, we
are searching for around 13.5:1 air/fuel ratio for a naturally aspirated engine.
Turbo, we are seeking from 12.0-12.5. Supercharger, you would want it
around 12.0 on the richer side of the spectrum because it generates so much
heat. Anyway, 13.5 or so for all motor, so you give it gas at 2000
and see the indicator that's datalogging jump up to column 9-10 pretty fast, and
you notice your at 15:1 air/fuel ratio as soon as you floored it to when you let
off at about 3000 RPM. You let OFF if your outside of say 13.9:1 or
higher, or say your richer than 11.0:1, you let off right away. Then,
instead of making adjustments to that one area from 2k-3k, its pretty reasonable
to assume your going to be lean (15:1) across much of the band, so go ahead and
add fuel in the last column all the way to your rev limiter.
If you make a change to column 10, always change column 9 the same amount!
So if you adjust 5% richer across 10, do it to 9 also. The reason is, you
might not be exactly the vacuum of column 10, just barely into it, and the
computer is using the numbers from 9 AND 10 and extrapolating. So change
both, and you don't have to worry.
Don't forget to switch the tables to VTEC table, which is the number 2 on the
fuel icon. In the picture above, the number 1 fuel icon is
indented...showing you your on the non-vtec lobe. Pay attention to where
your making changes, you want to be making changes in the right table!
VTEC or Non-Vtec. 1 or 2. so now you made a pas up to about say,
6500 RPM, and your letting off every time you go outside your parameters.
So if your up at 7000 RPM your motor should be tuned for air/fuel ratio pretty
damn good up to that point. When you get up around a point where your in
VTEC and have gone a little past VTEC, you will get a graph like this:
You had put your VTEC at 5000 RPM, and when you hit VTEC it was too soon, as
noted from that dip from 5k-5800 you see there. So then that should turn a
light bulb on your your head to think "well, it would be nice if I couldn't
even feel the VTEC transition, and it was just a straight line" Well
exactly. So now, you look at the point where your curve below 5k would hit
the line in VTEC above, if it carried on its current trajectory upward, and
forward. Take into account its going to not be straight, it will probably
round down slightly. Take a good guestimate in your head and then place
VTEC where you might think its going to be a good transition. In this
case, VTEC will probably come in at 5700-5800 RPM and the graph will clean
up nicely. This is a shortcut method, so you don't spend 7 passes
trying to find the proper VTEC point. We also don't want to focus on
tuning that much above VTEC until our permanent VTEC point is discovered because
changes in your VTEc point will have an effect on fueling after VTEC. Now
your graph should look like this:
Also, note in the above picture I might be able to bring the VTEC down like 100
RPM to make it more of a perfect straight line? You could do this, but if
you do, you won't feel when VTEC comes in and it will be just a noise. I
have a philosophy on this subject and I believe the Honda experience should be
fun to drive. So what I do is set the VTEC 100, or even 200 higher than
its "straight line" position, so that when the customer hits VTEC, the
torque jumps up like 10 LBS and the HP climbs steeply up and he gets thrown back
in his seat a little bit. It makes the car feel "quick" in that
area, and makes it more fun to drive. On 2 liter motors especially, I like
to make it steep after it hits VTEC so the customer can chirp the tires just
hitting VTEC. Like this graph for example...
See the area I circled? I could have easily set the VTEC 200 RPM lower so
that the graph went up less steeply after VTEC, but I wanted the customer to
feel the VTEC power when it kicked in. See the torque immediately jump up
10-15 lbs in an instant? The guy gets a little chirp out of it, and gets
him excited about driving his car. The job of the tuner is not only to
make the air/fuel ratio great and the car safe to race, but to make the car FUN
TO DRIVE. BTW, you can mess with VTEC points like this all day long and it
does not make the car any slower in a race, because only a beginner would be at
that low of an RPM on a VTEC motor racing anywhere.
HIGHER RPM's Your motor will want fuel up to a certain RPM, and
then it will want a little bit taken away, or the fuel curve will flatten out.
Look at the graph here, below. See how from like 6500 RPM to like 9000 RPM
the fuel is pretty similar? That is how most engines are. And if you
went past 9000 RPM, the fuel might be a little less, you can see at a certain
point it peaks, then the fuel backs off slightly. Remember this when your
tuning, so make sure the graph is smooth, and not all bumpy.
Ok, we have come a long way already, and we need to finish up. Well what
about columns 6-8? We never really talked about that much. You could
have taken care of those in 2 ways. You could have done them after you did
1-6 in the narrow throttle and tuned them before you started the full throttle,
or you can do what I do which is effective also.
Columns 6-9 are all 13.5:1 Air fuel ratio on most vehicles, except boosted ones,
where on them column 9 would be like 12.5:1 perhaps or 12:1. Also of note,
its pretty difficult and hard on your engine to sit there on a dyno at 8,000 RPM
and tune for columns 6-8. Its hard to do it even at 3,000 RPM sometimes.
Because what happens is your letting on and off the throttle and thats junk,
because your injectors are going nutz on and off. So do this. Take
your mouse and highlight from column 6 to column 9, and then go to the menu
under edit, and do: "Interpolate Selection" or ALT-E, this will
average between column 9 and 6 everywhere in between and give you a nice smooth
transition to full throttle. But notice it won't change the number on
column 6 or 9. Remember, you can do this step before you start the full
throttle exercise but its more difficult also if you don't know your precise
VTEC point. Then go and test the air/fuel ratio in a few area's in your
matrix to see how good the interpolate was. then make minor adjustments
from there. I have datalogged probably 3 thousand miles in various cars
before and I have not even once, cruised in columns 7-8 ever. I am either
giving it gas to get on an onramp in like columns 4-5, or I have given it almost
full throttle and I am in column 9. Columns 7-8 are really just
transitional areas to full throttle, and rarely used daily.
Now I have 13.3-13.6 or so, Air fuel Ratio all the way across, what now?
Before we tune the timing curve, we are going to play with the cam gears, or
IVTEC, etc. Start with the timing cam gear first (the one on the other end
of the distributor). When you move this cam gear, it will affect timing,
so get your timing gun out and put the timing back to exactly 16 degrees after
you move the cam gear. We do one cam gear at a time, starting with the
timing one first. Do a pass, notice the graph move up or down, start with
a modest adjustment like +1. If it likes it, go more, until your engine
builder says its unsafe. If it likes +1, then it likes +2 even more, you
can count on it thats its going to hate -1, or more...heck motors might like +6,
if you have that much clearance in your piston/valve & valve/valve.
Now that the distributor/timing cam gear is done, move to the other one.
Adjust that one...this one doesn't affect the timing, so it goes pretty fast.
TIPS: If you advance the intake cam gear and retard the exhaust, you
bring the valves closer together. So with big cams, you probably don't
want to advance the intake cam gear too much, because that will bring the valves
closer to hitting the pistons, and if you left the exhaust gear at 0, its
bringing it closer to that valve too. So as a rule of thumb with motors
with tight tolerances, your going to want to leave the intake cam gear around 0,
or +1, and ADVANCE the exhaust cam gear to like minimum +2. You
advance your exhaust cam gear, you move the valves farther away from each other,
and reduce overlap!
Now its time to fine tune the timing curve. Now we got the cam gears
to where the motor is breathing nicely, and it likes it... Start out with a nice
blanket of say 2 degrees advanced across the entire wide throttle 9-10 area, in
both non-vtec and VTEC. see if it likes that. If it likes it up to
say, 7000 RPM, add maybe 1/2 a degree more before there and then go back and
lower it after 7k, slowly. You don't want to go from say 34, to say 30
right away, you want a smooth transition like 33, 32, 31, etc. The higher
RPM you go, the lower timing it will probably like in most cases. So you
might have a peak timing of say 33 on the matrix at 8000 RPM, and then at 9k
your timing is 31, then at 9500 your at 29. At this point your tuning for
maximum upper range horsepower, since your lower range is probably lines over
lines at this point. So you do 1/2 a degree at a time in the upper areas
until you get the power to carry on as long as possible. Now that you have
the timing perfect, or as good as you can get it all up there, you take a step
back to fuel...
Back to Fuel... This is a short step and may only take 2 passes.
Changing the timing/cam gears could slightly alter the air/fuel ratio, but if
your only adjusting a couple degrees, probably not noticeably. But anyway,
for maximum power, now we are going to blanket change the power band to see how
the motor likes it. We highlight from say 7k-9500 and add 1% fuel across
that area, and do a pass. Did it like it? Did it run .2 richer?
If it liked it, do another 1/2 a percent until it reaches maximum. Do the
same for leaning it out 1% if the first pass of Richer was not good.
**REMEMBER THE AIR INTAKE TEMPERATURE MUST BE EXACTLY THE SAME EVERY SINGLE
PASS. You also want the water temp to be consistent too, because that
affects fuel too at a certain point. And you must start at the same exact
RPM each time, when you floor it. Consistency is key in tuning.
So now we have hit the cam gears, the timing curve, we have hit the fuel
curve 2x, and we are pretty much done. Now is the time to experiment with
other mufflers, or whatever, intakes, to see how it affects your ride. You
should have tuned your car exactly the same as your going to race it.
Don't show up at the dyno with a cat on your car, if you race with no cat.
That won't work at all.
Here are the mistakes people make when they go and tune:
-They changed the exhaust/header. Get your exhaust BEFORE you tune. or Go
fine tune again.
-They put on a High-Flow cat. Time to re-tune, now your running lean.
-They changed the cams...DO NOT DO THAT!
-They took off the cat to go race, now your probably melting pistons, your way
-They put in a different thermostat, and the car runs at a different water
temperature than when tuned. This will change the air/fuel ratio, don't do
-They thought they were smart and tried to mess with the timing, or fuel
pressure. When your done tuning, notice what your timing and fuel pressure
were, and MARK THEM. Do not change them. Even if you go up or down
in elevation, it is only going to run slightly leaner or richer, not crazy off.
-With a turbo, never change any aspect of your setup, if you do, go back to
tune. Wastegate, manifold, turbo, piping, intercooler, anything, or your
asking for trouble.
What is ok to change after I go tune?
-Most intakes are ok, unless your talking about going from stock, to cold
air, thats no good.
-Spark Plugs are ok.
-valve adjustment is ok.
-Oil change. LOL
-Air Filter is ok
As a general rule of thumb, something that affects airflow a great deal should
not be changed after the tuning. Unless you want to put it back up for a
few runs to adjust.
So in review we have a few basic steps here.
-Go to a dyno
-Get a buddy to assist you.
-You have to have a Wideband 02 sensor
-Set Idle at 14.7
-Set distributor/Timing at stock 16 degrees
-Make sure Hondata/Unit is set to 16 degrees
-Make sure your air intake temp is the same before each pass, and your water
temp is full warm and the same before each pass.
-Tune for 14.7 from column 1-5, and 6 for 13.6 up to VTEC or 6k or so.
-Do VTEC shortcut to find VTEC, remember, make the car fun to drive.
-Tune fuel for upper RPM's in VTEC
-Play with Cam gears
-Fine tune the timing, using blanket adjustments
-Go back to fuel, again, and use Blanket adjustments for fine tuning.
-Do not change anything on your motor after tuning that can affect air flow
greatly, unless you re-tune.
Now I would say your machine is pretty fine tuned. Pretty dang good.
The approach is systematic, its deliberate, and your not on there long at all.
You memorize the above, you know what your doing, and you will be consistent in
your tuning. The approach also makes it very hard to hurt a motor because
you have your observer there, and your going up the RPM's tuning it slowly, 1
pass to a new RPM each time until your perfect all the way up.
If you follow this approach, you will be successful at tuning cars. One
thing I did beyond what the above states is that I had my wideband directly
wired into my laptop, so that the air/fuel numbers showed right on my screen,
Those numbers are the air/fuel ratio the motor is in at that particular RPM, and
throttle %. So you can see, when I have these numbers, it makes it really
systematic. Most tuners do not have this like the above and simply look at
the air/fuel ratio on the dyno machine and make the changes manually. This
is an OK method, but that takes more time for sure and is less accurate.
So guys, if you have the Hondata dealer package, and you don't have your lambda
wired directly into your laptop, make it happen!! Its wonderful. I
would only say its not really necessary on a dynapack, because of the accuracy
of the loading at each RPM. But it would be better nonetheless to have it
like the above.
There are other options on the Hondata worth discussing, but they really don't
affect how to tune a car. Like for example, you can remove the knock
sensor on Hondata, any ECU, and for example, you can disable the 02 heater so
you can run your car just fine with no 02 sensors even plugged in. You can
even mess with the idle speed if your idle has a slight lope, you can fix that.
You can have your Hondata switch off your A/C after a certain throttle position.
You can set the boost cut at any amount you want, lmited by the map sensor you
have plugged in, and you can also set the rev limit anywhere you want. It
also has a NOS controller on board to change your timing curves and fuel curves
for when your on the unit.
Pretty smart little box this Hondata is. I recommend supporting Hondata by
buying from them, or their dealers. One of the better business's in our