Blackbird Rush
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| posted on 24/7/09 at 11:24 PM |
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Megasquirt and TPS
Been playing with the set up, ready to hopefully go for a start up but.....
The TPS reading seams a bit odd, originally i had the honda ignition box in parallel to the MS wiring for the TPS as the honda box had a TPS connected
when the engine used to be running carbs. (i'm only running fuel on the MS, Sparks from the stock honda box).
Anyway, with both MS & Honda connected i couldn't get a reading on megatune, however now i've disconnected the honda wires i can, but
when you open the throttle the dial in mega tune stays on 0% until nearly full throttle then jumps to 100%.
the TPS has 3 connections, 1 2 &3...
Resistance readings as follows:
Closed Throttle
1-2 =0.4 K ohms
2-3 = 5.4 K ohms
1-3 = 5 K ohms
Open throttle
1-2 = 5.4 k ohms
2-3 = 0.4 K ohms
1-3 = 5 K ohms.
Currently wired up as
1-signal to pin 22 on MS
2 (middle pin) - Ground
3 - 5 Vref to pin 26 on MS
Is my TPS the wrong range to work? or is my wiring up the swanny?
Also will the Honda box work OK without the TPS wires connected?
Cheers for any pointers.....
Ash
[Edited on 24/7/09 by Blackbird Rush]
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rachaeljf
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| posted on 25/7/09 at 02:11 AM |
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Hi, you need to have
1 to ground
2 to MS input pin 22
3 to +5 V
From your measurements, your TPS has a 5 kohm resistor track with each end connected to pins 1 and 3, and a ~400 ohm resistor in series with the
wiper, which is pin 2. The trick is, the two pins that remain unchanged in resistance as you move the wiper must be the ends of the track.
If the two ecus' input pins are reasonably high impedance you should be able to piggyback them to the one TPS. Can't be sure without
measuring and doing some sums! With MS correctly wired, try it piggybacked and see how it runs.
You can get MS to operate without a TPS, in "mapdot" mode, if the Honda ecu is unwilling to share the TPS.
Cheers R
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mark chandler
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| posted on 25/7/09 at 08:02 AM |
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On mine when I calibrate TPS I get a range of 18 closed & 102 open, the system prompts me with is this correct and I agree. This is fine.
To make the dials work on the laptop screen you need to open the megasquirt-I.ini file and edit a couple of lines:
tpsADCGauge = tpsADC, "TPS ADC", "", 0, 100, -1, -1, 80, 95, 0, 0
throttleGauge = throttle, "Throttle Position", "%TPS", 0, 100, -1, 1, 90, 100, 0, 0
tachometer = rpm, "Engine Speed", "RPM", 0, 13000, 300, 600, 9000, 11000, 0, 0
Regards Mark
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Blackbird Rush
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| posted on 25/7/09 at 08:15 AM |
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Cheers GuysI'll give this a whirl.
I was getting similar readings when calibrating the TPS and swaping the pins round trying to get it to work, Megatune prompted that the numbers looked
odd but asked if i wanted to use them.
Mark, i think i've got your map loaded you sent me, any way of checking what i'm seeing is your map? any advice on the first start?
Cheers
Ash.
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mark chandler
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| posted on 25/7/09 at 08:24 AM |
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Point to note, those values above reflect what I had, if you look at the top off the
megasquirt-I.ini
file it describes the numbers, and what they do, the first set the couple set the range so my TPS was 18 - 102 so I used 0 to 100, the others merely
control the dial colour to warn you that you are thrashing it to death!
I should really edit mine to may 15 - 105 as the range but it works so I am happy.
As long as the TPS range goes from small to large you are fine.
Cheers Mark
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matt_gsxr
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| posted on 25/7/09 at 08:37 AM |
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Mark,
There are a couple of other requirements of the TPS value. These relate to Flood Clearing mode, and EGO thresholds.
If you can arrange closed to be below 155 and WOT about 178 then you won't lose any functionality
Megasquirt_TPS_instructions
With these values you will no longer get that warning (which isn't actually very helpful as it doesn't include these numbers!).
Matt
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mark chandler
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| posted on 25/7/09 at 08:58 AM |
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Thanks Matt, the problem I have with the 954blade TB's is the TPS does not have the range, so I lose the flood clear mode which can be a pain on
a fireblade engine!!!
Maybe I need another look in the ,ini files to see where this setting is coded.
Cheers Mark
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Blackbird Rush
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| posted on 25/7/09 at 10:04 PM |
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Well i left the tps disconnected to the honda box and swapped around the pins, hey presto a sensible reading on the calibration box and the megatune
gauge went up & down nicely when the throttle was opened & closed.
Didnt change the .ini file.
Had to bypass the Fuel Pump relay as the MS doesn't appear to be sending a signal to run the pump. any way of checking this easily?
Now for the bit i wasn't expecting.........
Put some fuel in it.........
bypassed the FP relay.......
switched on the ignition.....
pushed the start button.....
and.......
She runs!  if a bit lumpy...
Dead Chuffed! thanks for the help guys, i can see more questions being asked as i explore this further.....
Ash.
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