Widebands and Tuning
By Bill (allthegoodnamesaregone/missing2)
There are a lot of reasons to
get your hands on an in-car wideband setup. Common reasons range from the
ability to tune on the street or at the track, data acquisition, avoiding
costly dynometer time, and safety. Hopefully this document will help clear up
things you may want to consider when purchasing a wideband gauge and how to use
them.
You know you want one, but why!?
ANYONE and I mean anyone with a modified car can benefit from a wideband gauge.
With forced induction, nitrous, and big all motor setups you would be crazy not
too. Think of the hundreds or even thousands of dollars you spent on your
engine. Do you want to leave your air fuel ratios up to chance? Even the best
of tuners sometimes make mistakes at the dyno, or perhaps your local shops
sensor is old and has never been serviced. An in-car wideband is cheep
insurance in those cases, most costing under $500. For the DIY tuner or if you
are new to tuning they would be a must have for obvious reasons. I personally have yet to take my car to a
dyno since I obtained my wideband gauge, thus saving a lot of money. I have
found that tuning the car under street conditions provides a more accurate tune
as well. Keep in mind this is fine for
slower “street cars”, a few 0-60 blasts never hurt anyone, however if you are
cracking into the low 12’s / 11’s you may want to consider taking it to the
track. Even then a few days at the
track is cheep in comparison to $100-150 an hour on the dyno.
Also keep in mind that narrow band
gauges are cheep, but they are also pretty worthless. They can only accurately
read a “narrow band” of air fuel ratios depending on what they are calibrated
to read accurately. Example: The factory
ones on your car are designed around the AFR of 14.7 or the Stoichiometric
ratio for that given vehicle. And with
only one volt of output rage it dose not read much more or less then that
target AFR. Aftermarket ones have
different target AFR’s however they are still not good for tuning. I wouldn’t even use one as a safety measure
because they are simply inaccurate. There
is a lot of good information on the net about this topic already so I will stop
here. All you really need to know is that narrow band sensors are worthless if
you are doing your own tuning.
Things to consider before buying a gauge:
- What type of output does it have? (Some are only 0-4 volt or pseudo widebands
try and stay away from those)
- Required features: Portability? Gauge readout/style? AFR Range? ect..
- As we all know you want a high quality gauge. There are a lot of cheep gauges
out there, go with a brand name you know and trust. You should also ask around
and do some research yourself. It’s a growing market and there are new companies
jumping in every day.
- Make sure that it will work with your data logging or engine management
system?
Typically, most gauges will offer
an analog or digital display, 5-volt analog output, narrow band simulated
output, and some form of data logging. Look for one with a good easy to read
display. At the track while you are taking a pass, you are not going to have
the time to read a number, look for a gauge with a sweeping display as well as
the raw numbers. Both the LM1 and the AEM wideband gauges offer this feature
(additional cost on the LM1). I prefer the AEM as it is color coded, which is handy.
It makes it so if I am way off I know
almost instantly even if I am not looking directly at the gauge. A benefit of
the LM1 however is that it is somewhat portable with a few inexpensive sensors
one could take the wideband with them to various cars. This cuts costs if you
use the system with friends, or have a lot of cars you wish to use it on. The
LM1 also offers a few additional data acquisition options at an additional
cost.
With software like HP Tuners on the
rise, that have wideband inputs, the generic pre-packaged data acquisition
systems that come with wideband systems are less important. In that case all
you need to be concerned with is that it has the proper 5-volt output. If you
plan on buying a Tuning package such as HP Tuners, be sure to buy it with the
inputs for the wideband gauges output. It’s worth EVERY PENNY to be able to log
the wideband readings along with all of the other various engine parameters in
real time directly from the ECM. It’s less critical for the casual user, but
almost essential for the DIY tuner.
SO make sure you have an easy to
read display, and connectivity with your logging or EMS applications and you are
ready to go. The installation is pretty strait forward on most wideband
systems. Anyone familiar with installing car stereo equipment is probably
capable of wiring it in under two hours depending on the vehicle/system.
However keep in mind you will probably need to take the car to an exhaust shop
to have a bung welded in to your exhaust tract. You will want to install it
before your catalytic converter, but after your y-pipe for a single sensor
setup.
What is all of this good for again?
Now that you have your sensor picked out, installed, and your tuning software
configured. You are ready to go. This section I need to leave somewhat generic
as tuning is different from car to car. However I will cover some of the
benefits of using HP Tuners with a wideband setup. On most modern GM cars there
are two forms of tuning; Mass Air and Speed Density. Most people don’t need to
worry too much about Speed Density, and it is well beyond the scope of this
article and this author’s experience (but will be soon).
Unless failure occurs your car will
run fueling based on its mass airflow sensor. In the event of a failure it
falls back on speed density and runs off your VE tables. Thus VE tables are not
an essential part of tuning, but more a safety net in the event that your mass
air system fails. They should be addressed as well once your MAF tune is in
order.
The Mass Air sensor takes a reading
and after various adjustments via other sensors and parameters it calculates
the amount of fuel to be injected into your motor. It is important to
understand what the enrichment and enleanment tables do to your base mass air
calculations when tuning. After careful review of histograms and other engine
data you can begin to make changes. Take it slow and in small increments. Also
never edit a value if you are not 100% sure of what it does. Key tables for
most people will be the MAF table and the PE (power enrichment) tables. These
tables offer the most consistent and radical changes to your engines fueling.
Edit with caution, and verify your changes by taking a peek at your wideband’s
readings after you load your new tune.
Take it slow, ask a lot of
questions, and it will be fine. Also keep in mind this document is not intended
to offer any advice on how to tune, that is left up to you the user. I cannot
be held responsible for poor judgment or damage to your engine. Spend some time
reading your product documentation, and be careful out there.
Thanks for the great information Bill.
Now that you want to learn even more about wideband tuning
check out the tutorial videos at LM101.
http://www.innovatemotorsports.com/resources/lm101.php
AEM LM1
