by Dave Koehler
Hi Dave - Mad Coater here,
I occasionally run a Crower injected
Alky RED [newly retired on 10/1/03 = less
play time $$$, but its my test bed,
so off I must race] to test my latest
coating blends and/or mechanical inventions.
Ive been experimenting with O2
sensors as a better way to tune for overall
fuel mixture. EGT sensors are nice for
cylinder to cylinder reference [helps
when the nozzles can be fine tuned], but
Im thinking that a good Lambda sensor
could help the OVERALL tuneup and final
bypass pill setting(s).
Weve been building and refining
our own O2 sensor kits for a year now
- seems to work pretty well on both gasoline
and Alky. What are your thoughts on this
type of sensor feedback?
Bruce T. Corneto
[The Mad Coater]
The five wire heated sensors will work in the
rich A/F range that race cars run in. This is
particularly useful for nitrous, blowers and
mechanical injection combos that have, by their
nature, excess fuel to deal with. As much as
I like some of the high tech stuff that has
come along, this is one of those things I have
not tried. Here is my take on this.
I question that if we know the A/F going down
track, how many more opening and closing poppets,
solenoids, timers and relays will we need to
make use of this information. Its a good
news/bad news kind of thing.
The Up Side:
When used in conjunction with egt sensors the
lambda sensors can allow you to determine whether
a high EGT is due to being too lean or is being
generated by too much fuel burning in the pipes.
This may or may not be easier, time wise, than
the poor mans Lambda meter, the spark plug and
ET slip, but one does get a number to look at
and ponder plus the cool factor is way up there.
The Down Side:
Due to the costs of this technology a racer
is limited to using these with collector headers
and you still need two sensors plus an interface
to your data logger. Zoomie headers are pretty
much out of the picture at this point because
just reading one or two cylinders will probably
confuse more than clear up the overall picture.
The Far Side:
I dont think there is any question these
can be used along with plug reading, EGTs and
ET slips to make tuning decisions that much
easier ... or more confusing. While I may never
get around to trying this it is certainly a
viable tool that bears study. I just dont
know if the time has come for it to be considered
a must have necessity on a drag
OK, my answer was ulterior motivated. I will
ask you to write an article on this subject
along with your real world experiences and observations
and submit it to DRO. The editor loves tech
articles and you may convince me to spend more
of the kids college money.
Have a safe race
Thanks for the informative response to
my first question. I have a follow-up.
By factoring in the inlet air temp you
can derive a corrected EGT, which is quite
lower than the actual reading. Which temp
is more important to tuning? My gut
feeling is that no matter what the factored
EGT reading is (usually 100-200 degrees
lower), the actual EGT temp is what the
exhaust valve and the rest of the exhaust
system (and turbo) is subjected to and
you should be tuning based upon that.
How do these two temps relate to each
Also, when changing from a 1 bar to a
2 bar MAP sensor, should the kpa readings
stay the same? When the ignition is turned
on (without the car running) the MAP sensor
will read the atmospheric pressure. Since
both read a 0-5V signal and you have now
doubled the range, should the 2 bar have
a higher reading than the 1 bar at the
Drake Coatings Inc.
Interesting. I never gave something like this
a thought. I know just enough about the electronic
side of EFI to be dangerous, but the end game
is the same. I would use the exhaust egt for
cyl to cyl adjustments. Once you know what the
engine likes, you can see if there is any correlation
between the inlet and the exhaust temps that
Question 2: As I see it, a 2 bar MAP just allows
higher boost pressure (29 lbs.) to be used and
measured. If the new sensor also reads 0-5V,
then a parameter has to be changed in the software
so that it knows that it now reads 0-29 lbs.
or whatever type of number you need to see.
It is normally input as a millivolts figure.
At least thats the way sensors and software
I deal with works.
Have a safe race,
Dave Koehler answers your
nitrous & fuel-injection