Vehicle N20 Control
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Posts: 46,084
Hi guys.
I'm in the process of needing to design a failsafe for one of my cars
running nitrous.
The nitrous system works like this. There is a arming button inside of the
vehicle. When the arm button is off, the system is shut down. With the arm
button on, the system is armed. The nitrous will only kick in when the
engine is at WOT (wide open throttle) and the system has been armed. It
knows its at WOT by measuring the TPS signal on the car (throttle position
sensor).
One of the major problems is that the stock computer in the car does a fuel
cut at redline (this case, 6250rpm). If by mistake I hit redline before
shifting, and the engine is at WOT, nitrous will still be flowing (but fuel
won't be), and there goes the engine.
Basically what I need to do is use the BS2 to cut the arming signal when the
engine reaches a safe 6150rpm or so. This will ensure that the N20 is no
longer flowing incase the fuel cut is hit.
The RPM signal can be read off of one of the lines going into the computer
on the car. The data I have for this is :
Engine speed output Signal: (V) 0-13, or more Note: Waveform
I assume the signal is the same as most modern EFI cars. I'm not sure how
to read this data into the BS2 however.
I think I can read the TPS sensor data in with a ADC, since its just a
normal 0-5V signal.
I also need to be able to cut the 12V signal from the arm switch to turn the
nitrous off assuming the TPS is at WOT, and the engine is above a
predetermined RPM.
I would also like to hook it up to a narrow band oxygen sensor to shut it
down if the mixture becomes too lean (this is a 0-1V signal. Not sure how
to get this info into the BS2. ADC again? What to use as a reference
voltage however?).
Any suggestions on the best way to go about doing this? Please let me know.
Thanks.
I'm in the process of needing to design a failsafe for one of my cars
running nitrous.
The nitrous system works like this. There is a arming button inside of the
vehicle. When the arm button is off, the system is shut down. With the arm
button on, the system is armed. The nitrous will only kick in when the
engine is at WOT (wide open throttle) and the system has been armed. It
knows its at WOT by measuring the TPS signal on the car (throttle position
sensor).
One of the major problems is that the stock computer in the car does a fuel
cut at redline (this case, 6250rpm). If by mistake I hit redline before
shifting, and the engine is at WOT, nitrous will still be flowing (but fuel
won't be), and there goes the engine.
Basically what I need to do is use the BS2 to cut the arming signal when the
engine reaches a safe 6150rpm or so. This will ensure that the N20 is no
longer flowing incase the fuel cut is hit.
The RPM signal can be read off of one of the lines going into the computer
on the car. The data I have for this is :
Engine speed output Signal: (V) 0-13, or more Note: Waveform
I assume the signal is the same as most modern EFI cars. I'm not sure how
to read this data into the BS2 however.
I think I can read the TPS sensor data in with a ADC, since its just a
normal 0-5V signal.
I also need to be able to cut the 12V signal from the arm switch to turn the
nitrous off assuming the TPS is at WOT, and the engine is above a
predetermined RPM.
I would also like to hook it up to a narrow band oxygen sensor to shut it
down if the mixture becomes too lean (this is a 0-1V signal. Not sure how
to get this info into the BS2. ADC again? What to use as a reference
voltage however?).
Any suggestions on the best way to go about doing this? Please let me know.
Thanks.
Comments
signal the duration will be 160 usec at 6250 RPM and 162.6 usec at 6150
RPM. Looks like you need to drop the arm signal if pulsein sees a
signal some where between these two ranges.
Will this work? SOunds good, except I don't know the limits of pulse
in, if not al's Pak 7 would also be something to check out probably work
for you!
http://www.al-williams.com/awce/pak7.htm
regards
Leroy
Tarun Tuli wrote:
>
> Hi guys.
>
> I'm in the process of needing to design a failsafe for one of my cars
> running nitrous.
>
> The nitrous system works like this. There is a arming button inside of the
> vehicle. When the arm button is off, the system is shut down. With the arm
> button on, the system is armed. The nitrous will only kick in when the
> engine is at WOT (wide open throttle) and the system has been armed. It
> knows its at WOT by measuring the TPS signal on the car (throttle position
> sensor).
>
> One of the major problems is that the stock computer in the car does a fuel
> cut at redline (this case, 6250rpm). If by mistake I hit redline before
> shifting, and the engine is at WOT, nitrous will still be flowing (but fuel
> won't be), and there goes the engine.
>
> Basically what I need to do is use the BS2 to cut the arming signal when the
> engine reaches a safe 6150rpm or so. This will ensure that the N20 is no
> longer flowing incase the fuel cut is hit.
>
> The RPM signal can be read off of one of the lines going into the computer
> on the car. The data I have for this is :
>
> Engine speed output Signal: (V) 0-13, or more Note: Waveform
>
> I assume the signal is the same as most modern EFI cars. I'm not sure how
> to read this data into the BS2 however.
>
> I think I can read the TPS sensor data in with a ADC, since its just a
> normal 0-5V signal.
>
> I also need to be able to cut the 12V signal from the arm switch to turn the
> nitrous off assuming the TPS is at WOT, and the engine is above a
> predetermined RPM.
>
> I would also like to hook it up to a narrow band oxygen sensor to shut it
> down if the mixture becomes too lean (this is a 0-1V signal. Not sure how
> to get this info into the BS2. ADC again? What to use as a reference
> voltage however?).
>
> Any suggestions on the best way to go about doing this? Please let me know.
>
> Thanks.
>
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--
*******************************************************
* Leroy Hall *
* 317 Cherokee Drive *
* Loveland, Ohio - USA 45140-2404 *
*******************************************************
* Phone: (513) 697-7539 *
* Cell : (513) 300-8632 *
* Email: leroy@f... *
* Home page URL: http://home.fuse.net/leroy/ *
* Resume URL: http://home.fuse.net/leroy/resume.htm *
*******************************************************
* Leroy Hall *
* 317 Cherokee Drive *
* Loveland, Ohio - USA 45140-2404 *
*******************************************************
stamp needs 5V? Whats the best way of doing this?
Thanks.
--- In basicstamps@y..., "Leroy Hall, Senior" <leroy@f...> wrote:
> Looks like a simple job for pulsein. If you can monitor a direct
RPM
> signal the duration will be 160 usec at 6250 RPM and 162.6 usec at
6150
> RPM. Looks like you need to drop the arm signal if pulsein sees a
> signal some where between these two ranges.
>
> Will this work? SOunds good, except I don't know the limits of
pulse
> in, if not al's Pak 7 would also be something to check out probably
work
> for you!
>
>
> http://www.al-williams.com/awce/pak7.htm
>
>
> regards
>
> Leroy
>
> Tarun Tuli wrote:
> >
> > Hi guys.
> >
> > I'm in the process of needing to design a failsafe for one of my
cars
> > running nitrous.
> >
> > The nitrous system works like this. There is a arming button
inside of the
> > vehicle. When the arm button is off, the system is shut down.
With the arm
> > button on, the system is armed. The nitrous will only kick in
when the
> > engine is at WOT (wide open throttle) and the system has been
armed. It
> > knows its at WOT by measuring the TPS signal on the car (throttle
position
> > sensor).
> >
> > One of the major problems is that the stock computer in the car
does a fuel
> > cut at redline (this case, 6250rpm). If by mistake I hit redline
before
> > shifting, and the engine is at WOT, nitrous will still be flowing
(but fuel
> > won't be), and there goes the engine.
> >
> > Basically what I need to do is use the BS2 to cut the arming
signal when the
> > engine reaches a safe 6150rpm or so. This will ensure that the
N20 is no
> > longer flowing incase the fuel cut is hit.
> >
> > The RPM signal can be read off of one of the lines going into the
computer
> > on the car. The data I have for this is :
> >
> > Engine speed output Signal: (V) 0-13, or more Note:
Waveform
> >
> > I assume the signal is the same as most modern EFI cars. I'm not
sure how
> > to read this data into the BS2 however.
> >
> > I think I can read the TPS sensor data in with a ADC, since its
just a
> > normal 0-5V signal.
> >
> > I also need to be able to cut the 12V signal from the arm switch
to turn the
> > nitrous off assuming the TPS is at WOT, and the engine is above a
> > predetermined RPM.
> >
> > I would also like to hook it up to a narrow band oxygen sensor to
shut it
> > down if the mixture becomes too lean (this is a 0-1V signal. Not
sure how
> > to get this info into the BS2. ADC again? What to use as a
reference
> > voltage however?).
> >
> > Any suggestions on the best way to go about doing this? Please
let me know.
> >
> > Thanks.
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@y...
> > from the same email address that you subscribed. Text in the
Subject and Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
>
> --
>
> *******************************************************
> * Leroy Hall *
> * 317 Cherokee Drive *
> * Loveland, Ohio - USA 45140-2404 *
> *******************************************************
> * Phone: (513) 697-7539 *
> * Cell : (513) 300-8632 *
> * Email: leroy@f... *
> * Home page URL: http://home.fuse.net/leroy/ *
> * Resume URL: http://home.fuse.net/leroy/resume.htm *
> *******************************************************
> * Leroy Hall *
> * 317 Cherokee Drive *
> * Loveland, Ohio - USA 45140-2404 *
> *******************************************************
>stamp needs 5V? Whats the best way of doing this?
It might be a good thing to use an OptoIsolator for this. I don't know a
huge amount about motor cars EXCEPT that all the electronics in them have to
be pretty much bomb proof [noparse]:)[/noparse] It might also be a good idea to make the
system failsafe so that if there is no frequency at all then the N2O unit
will not function. The 0 - 1 V signal can easily be boosted up (again an
optoisolator would be useful here) in fact if you get an optoisolator with
an opamp on the output stage then this voltage could probably go straight
in. I don't know how N2O works but I was thinking that an additional
failsafe could be added by fitting a microswitch to the top of the clutch
pedal so that if the clutch was pushed out then the N2O would stop working
(does this make sense ?).
Justin "Can I fit this to my Deux Chevaux?" Pentecost
Focus Puller and Basic stamp Idiot
> I assume the signal is the same as most modern EFI cars. I'm not sure how
> to read this data into the BS2 however.
Scale the voltage with a divider and then put it into the ADC. See below.
Vin (0-13V)
|
|
R1
|
|
---- Vout (0-5V)
|
|
R2
|
|
GND
Vout = Vin (R2/(R1+R2))
Solve for Vin = 13V, Vout = 5V, and R2 = some value. You can make R1 and R2
high values and limit the loading of the original signal, but most A/D
converters need a low input impedance. If the signal is a DC signal you can
add a capacitor from Vout to GND. If it needs fairly good response time (as
you will likely need), then you might put an op-amp follower between Vout
and the input to the A/D converter. If the original signal can stand lower
resistances then you can set R1 + R2 to around 10K and it should be OK to
just feed the Vout directly into the A/D converter.
This is all assuming the 0V of the signal is the same 0V as the ADC.
> I think I can read the TPS sensor data in with a ADC, since its just a
> normal 0-5V signal.
Just make sure your ADC can take 5V in ... some are set up to only take
0-4.092V in ... if it needs the lower level, just put a divider on it as
well.
> I also need to be able to cut the 12V signal from the arm switch
> to turn the
> nitrous off assuming the TPS is at WOT, and the engine is above a
> predetermined RPM.
5V relay, use the contacts to break the wire when you want to. If you use a
relay with a normally closed set of contacts, you can let the signal through
normally and then kill it when your stamp says to. If you want a more
"failsafe operation", use the normally open set of contacts and make the BS2
"allow" the ARM signal to get though when it's ready. This way if there is
trouble with your BS2, it is more likely to fail in the case where the ARM
signal is not let through when it should be than when it shouldn't be [noparse]:)[/noparse] ...
(of course, i'd have to look at what sorts of modes the BS2 might fail in,
what it's pins go to in reset, etc... so one way may be better than the
other depending on things I don't know).
To drive the relay, use a 2n2222 transistor (or equivalent) to drive the
coil. Hook the + side of the coil to 5V, the - side to the collector of
transitor. Hook the emitter of transistor to ground. Hook the base to the
BS2 through a limiting resistor. When the BS2 pin is low, then transistor is
off and the coil is not energized. When the pin is high, there is current
flowing into the base of transistor and it will energize the coil. When you
turn the transitor off there needs to be a diode to catch the energy in the
coil or it will destroy things, so add a 1N914 or 1N4148 diode around the
coil. See below.
ARM IN -> NC contact of Relay >>> COM contact of relay --- ARM OUT ->
+5V
|
| |
|
Relay Coil / \
| / \
|
| |
|
|C
\
\|B______ (100-1000) ohm resistor ____ BS2 pin
/|
/
|E
|
GND
The resistor value is more complicated than I want to go into .... but look
at the Voh specs of the BS2. If it says 2.4V at 8mA, then make the resitor
(2.4V-0.7V (transistor drop)/8mA). That should be close enough if your using
a small signal relay.
> I would also like to hook it up to a narrow band oxygen sensor to shut it
> down if the mixture becomes too lean (this is a 0-1V signal. Not sure how
> to get this info into the BS2. ADC again? What to use as a reference
> voltage however?).
Well, if you have enough resolution, you could just read it directly. If you
want more resolution, put it though an amplifier ....
GND---R1
R2
| |
| | |
--| - |
| >
OUT
---IN ---| +
| (this is supposed to be an op-amp)
OUT = ((R2+R1)/R1)*IN
So, for a gain of 5, R1 = 1K, R2 = 4K ... or thereabouts.
> Any suggestions on the best way to go about doing this? Please
> let me know.
>
> Thanks.
Your welcome [noparse]:)[/noparse] ... the things I do to get out of homework .... (just
started grad school after many years working in industry .... durn DSP is a
lot harder if you can't even rememeber how to multiply 2 sin waves together
.... ) ...
[noparse]:)[/noparse]
John ... back to reading ...
> Hi guys.
>
> I'm in the process of needing to design a failsafe for one of my cars
> running nitrous.
>
> The nitrous system works like this. There is a arming button inside of the
> vehicle. When the arm button is off, the system is shut down. With the arm
> button on, the system is armed. The nitrous will only kick in when the
> engine is at WOT (wide open throttle) and the system has been armed. It
> knows its at WOT by measuring the TPS signal on the car (throttle position
> sensor).
>
> One of the major problems is that the stock computer in the car does a fuel
> cut at redline (this case, 6250rpm). If by mistake I hit redline before
> shifting, and the engine is at WOT, nitrous will still be flowing (but fuel
> won't be), and there goes the engine.
>
> Basically what I need to do is use the BS2 to cut the arming signal when the
> engine reaches a safe 6150rpm or so. This will ensure that the N20 is no
> longer flowing incase the fuel cut is hit.
>
> The RPM signal can be read off of one of the lines going into the computer
> on the car. The data I have for this is :
>
> Engine speed output Signal: (V) 0-13, or more Note: Waveform
>
> I assume the signal is the same as most modern EFI cars. I'm not sure how
> to read this data into the BS2 however.
>
> I think I can read the TPS sensor data in with a ADC, since its just a
> normal 0-5V signal.
>
> I also need to be able to cut the 12V signal from the arm switch to turn the
> nitrous off assuming the TPS is at WOT, and the engine is above a
> predetermined RPM.
>
> I would also like to hook it up to a narrow band oxygen sensor to shut it
> down if the mixture becomes too lean (this is a 0-1V signal. Not sure how
> to get this info into the BS2. ADC again? What to use as a reference
> voltage however?).
>
> Any suggestions on the best way to go about doing this? Please let me know.
>
> Thanks.
>
>
My .02,
This is the been there, done that answer having both built nb/o2 data
loggers and spray 600+hp worth of nos every pass (-:
When it comes to engine longevity I always use the simplest and least
failure prone means of protection. In this case I would use an MSD p/n 8950
to shut down power to the solenoids. The bsII could be used to do this but
you MUST make sure that your code is correct and when you design the
hardware you make it rf and emi proof. The environment in an automotive
setting is very harsh and if not taken into consideration will cause lock
ups/ resets and hangs. Price wise they are about the same. As for the o2
sensor sensing a lean condition and trying to correct it; consider
this.... Once the lean condition can be detected in the exhaust, damage is
already being done.
As for detecting tps, a quality switch to turn on the system at the
throttle body is best and least failure prone.
Use the bsII to read tps via adc, read o2 with adc (I used 1.4 vref), rpm,
and use pulse-in to read injector pulse and log all of your data.
One other option would be to raise the rev limiter like I did on my EFI
car to something you should never see ( 7900 for mine ) but this is not a
good idea IMHO (-;
Feel free to email me with any questions about the nos setup.
Good Luck,
Dale Harwood [noparse][[/noparse] N4VFF ]
internet> dale@h...
ax.25> n4vff@n4vff.#cha.tn.usa.noam
#include <std_disclaimer.h>
I took into consideration all the suggestions you made. I beleive the
MSD8950 is not compatible with my car (direct iginition. From what I could
find, it needs a feed off of a distributor?) Plus I need a two stage
system, something where it can activate at a certain RPM, and deactivate at
another.
I guess my real goal is to have something similar to the Venom N20 kit, but
at a much more resonable cost (they start at $1300!), plus its more fun to
build something myself ;-)
True, that once a lean condition is reached, damage is already done. Im
hoping to catch it right before it runs dangerously lean and starts burning
things up. The car actual has a wideband O2 sensor before the cats, and a
narrowband after. Im baseing it on the narrowband sensor for now (I haven't
figured out how a wideband sensor works. But im assuming thats its fairly
complex, since meters for it cost several hundren to thousands of dollars).
I have my EGT/AF meters to rely on, but just want one extra layer of
protection incase im not paying attention (same reason for have the rev cut
off).
As for the TPS microswitch idea, once again I need a lower and upper
threshold. The N20 system im using basis its activation off of the TPS
signal as well (ZEX).
You mentioned you had it hooked up as a datalogger? Im mainly concerned
about getting the RPM signal to the BSII. Would you mind sharing some of
your code/schematic? Was it tapped off of the ECU (im assuming my signal
comes from a crank pickup sensor). Ive already received several great ideas
from people already, im just not sure which will work the best. I guess my
second goal is to not destroy the computer on the car. I dont have a spare!
;-)
Thanks.
My .02,
This is the been there, done that answer having both built nb/o2 data
loggers and spray 600+hp worth of nos every pass (-:
When it comes to engine longevity I always use the simplest and least
failure prone means of protection. In this case I would use an MSD p/n 8950
to shut down power to the solenoids. The bsII could be used to do this but
you MUST make sure that your code is correct and when you design the
hardware you make it rf and emi proof. The environment in an automotive
setting is very harsh and if not taken into consideration will cause lock
ups/ resets and hangs. Price wise they are about the same. As for the o2
sensor sensing a lean condition and trying to correct it; consider
this.... Once the lean condition can be detected in the exhaust, damage is
already being done.
As for detecting tps, a quality switch to turn on the system at the
throttle body is best and least failure prone.
Use the bsII to read tps via adc, read o2 with adc (I used 1.4 vref), rpm,
and use pulse-in to read injector pulse and log all of your data.
One other option would be to raise the rev limiter like I did on my EFI
car to something you should never see ( 7900 for mine ) but this is not a
good idea IMHO (-;
Feel free to email me with any questions about the nos setup.
Good Luck,
Dale Harwood [noparse][[/noparse] N4VFF ]
internet> dale@h...
ax.25> n4vff@n4vff.#cha.tn.usa.noam
#include <std_disclaimer.h>
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