Throttle pot wiring Megasquirt
Discussion
Alpha-N is normally used on cars using individual throttle bodies, or cars with really wild cams where the vacuum signal is really erratic on idle. Basically for nutterb
d racing engines. The quantity under measurement is the amount of air flowing through the intake system at any time (mass flow rate), and generally plenum (if fitted!) vacuum is a good indicator of that quantity. Throttle opening is a reeeeeeasonable estimate of the mass flow of air, but by the time we're resorting to throttle angle, things are getting a bit tenuous, and the idle starts to get somewhat erratic. Seems to work well flat-out, which is perhaps all that matters on a race engine?
Basically use speed-density if at all possible - it'll give better road manners. Interestingly a pal of mine is working on a ToF ultrasonic type flow sensor for both true air speed and density...
Right, I'm off to find out why I'm getting lots of sync errors on Tuner Studio. Might be because the coilpacks are right above the VR crank sensor wiring, even though its screened... Harumph.
Ed.
P.S. The paid for version of MegaLogViewer HD is awesome. Well worth 40 bucks.
d racing engines. The quantity under measurement is the amount of air flowing through the intake system at any time (mass flow rate), and generally plenum (if fitted!) vacuum is a good indicator of that quantity. Throttle opening is a reeeeeeasonable estimate of the mass flow of air, but by the time we're resorting to throttle angle, things are getting a bit tenuous, and the idle starts to get somewhat erratic. Seems to work well flat-out, which is perhaps all that matters on a race engine?Basically use speed-density if at all possible - it'll give better road manners. Interestingly a pal of mine is working on a ToF ultrasonic type flow sensor for both true air speed and density...
Right, I'm off to find out why I'm getting lots of sync errors on Tuner Studio. Might be because the coilpacks are right above the VR crank sensor wiring, even though its screened... Harumph.
Ed.
P.S. The paid for version of MegaLogViewer HD is awesome. Well worth 40 bucks.
Mapping from TPS is dead easy and intuitive, its very easy to get a very good map very quickly.
For MAP to work well you need a steady signal, or addlots of signal smoothing, which hampers throttle response and makes things difficult to tune on transients (depending on how much smoothing you've had to use) ..
"expert" tuners will argue airflow meters are the better way, with MAP second, TPS last.
I disagree to a large extent in that for the home mapper, and most people earning a living at it, generally speaking you get a much much much better map using TPS as it's so easy to do, and much kinder on the car on the dyno because it's so quickto do (relatively speaking).
Don't let anyone tell you that TPS is just for race engines
all my road conversions are mapped TPS and have been for nearly 20 years. I see no good reason to change, and many good reasons to stay the same.
For MAP to work well you need a steady signal, or addlots of signal smoothing, which hampers throttle response and makes things difficult to tune on transients (depending on how much smoothing you've had to use) ..
"expert" tuners will argue airflow meters are the better way, with MAP second, TPS last.
I disagree to a large extent in that for the home mapper, and most people earning a living at it, generally speaking you get a much much much better map using TPS as it's so easy to do, and much kinder on the car on the dyno because it's so quickto do (relatively speaking).
Don't let anyone tell you that TPS is just for race engines
all my road conversions are mapped TPS and have been for nearly 20 years. I see no good reason to change, and many good reasons to stay the same.
ed_crouch said:
Alpha-N is normally used on cars using individual throttle bodies, or cars with really wild cams where the vacuum signal is really erratic on idle. Basically for nutterbd racing engines. The quantity under measurement is the amount of air flowing through the intake system at any time (mass flow rate), and generally plenum (if fitted!) vacuum is a good indicator of that quantity. Throttle opening is a reeeeeeasonable estimate of the mass flow of air, but by the time we're resorting to throttle angle, things are getting a bit tenuous, and the idle starts to get somewhat erratic. Seems to work well flat-out, which is perhaps all that matters on a race engine?
Basically use speed-density if at all possible - it'll give better road manners. Interestingly a pal of mine is working on a ToF ultrasonic type flow sensor for both true air speed and density...
Right, I'm off to find out why I'm getting lots of sync errors on Tuner Studio. Might be because the coilpacks are right above the VR crank sensor wiring, even though its screened... Harumph.
Ed.
P.S. The paid for version of MegaLogViewer HD is awesome. Well worth 40 bucks.
Thanks. d racing engines. The quantity under measurement is the amount of air flowing through the intake system at any time (mass flow rate), and generally plenum (if fitted!) vacuum is a good indicator of that quantity. Throttle opening is a reeeeeeasonable estimate of the mass flow of air, but by the time we're resorting to throttle angle, things are getting a bit tenuous, and the idle starts to get somewhat erratic. Seems to work well flat-out, which is perhaps all that matters on a race engine?Basically use speed-density if at all possible - it'll give better road manners. Interestingly a pal of mine is working on a ToF ultrasonic type flow sensor for both true air speed and density...
Right, I'm off to find out why I'm getting lots of sync errors on Tuner Studio. Might be because the coilpacks are right above the VR crank sensor wiring, even though its screened... Harumph.
Ed.
P.S. The paid for version of MegaLogViewer HD is awesome. Well worth 40 bucks.
These systems seem to be very critical in where they are grounded.
Are all your sensor grounds going back to the Ecu?
spitfire4v8 said:
Mapping from TPS is dead easy and intuitive, its very easy to get a very good map very quickly.
For MAP to work well you need a steady signal, or addlots of signal smoothing, which hampers throttle response and makes things difficult to tune on transients (depending on how much smoothing you've had to use) ..
"expert" tuners will argue airflow meters are the better way, with MAP second, TPS last.
I disagree to a large extent in that for the home mapper, and most people earning a living at it, generally speaking you get a much much much better map using TPS as it's so easy to do, and much kinder on the car on the dyno because it's so quickto do (relatively speaking).
Don't let anyone tell you that TPS is just for race engines all my road conversions are mapped TPS and have been for nearly 20 years. I see no good reason to change, and many good reasons to stay the same.
Fair comment - I perhaps shoulda qualified what I said by saying all of my "knowledge" on Alpha-N was from reading - I have never attempted to map Alpha-N because Ive always used MS on cars with decent, stable vacuum signal. For MAP to work well you need a steady signal, or addlots of signal smoothing, which hampers throttle response and makes things difficult to tune on transients (depending on how much smoothing you've had to use) ..
"expert" tuners will argue airflow meters are the better way, with MAP second, TPS last.
I disagree to a large extent in that for the home mapper, and most people earning a living at it, generally speaking you get a much much much better map using TPS as it's so easy to do, and much kinder on the car on the dyno because it's so quickto do (relatively speaking).
Don't let anyone tell you that TPS is just for race engines
all my road conversions are mapped TPS and have been for nearly 20 years. I see no good reason to change, and many good reasons to stay the same.I'm going to be converting my camper van to run Speeduino, might try mapping that off the TPS. See how I get on...
Anyway, I'm not here to spam joust - interesting to hear of practical experience showing Alpha-N can work on the road. One thing though - make sure the throttle pot is in FINE fettle and make sure its a good one...!
Yes its vitally important to have ALL sensors grounded back at the ecu. You need to make sure that there are no high current flowing in the same wires as the sensor grounds because high currents = voltage drop along the wire = transient offsets appearing in the sensor readings. If you fall foul of this the install will always be awful. EVERY sensor grounds to the ecu plug, and then the ecu grounds all go to the same point on the engine. Then all the engine grounds go to the chassis, then the chassis is connected to negative terminal of battery.
This is really important - never pollute the sensor readings by making them share grounds with high power devices.
This is really important - never pollute the sensor readings by making them share grounds with high power devices.
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