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Old 11-07-2014, 11:20 AM   #1
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Default VTPS calibration problems

I installed the auto tps on my 1.6l and wired it per Joe Perez instructions, Red/black from tps to red (car), black to black and green to green leaving the auto tps red cable off.
When I go to tuner studio to calibrate the tps there is a blue bar under the calibration that keeps increasing.
For example when I do the closed tps is "10", then 2 minutes later increases to "23", then "50" after 5 minutes. ANd the open calibration reads exactly the same.

Then I wired it differently (per another member's suggestion)

Green red from tps to red in car
black green from tps to black green from car
Red black from tps to green white in car.

THe same problem happens, and yes, I did the modification in my mspnp, (actually I opened it up and it was already done by previous owner)

Any help is appreciated, I dont have a voltmeter
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Old 11-07-2014, 01:24 PM   #2
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thanks for the help.....

I have the factory manual and this is what I got.

For a manual tps this is how my plug looks.
(from the top pin to the bottom)
1.Green manual says "POW" what is this?
2. Black manual says "TL" ????
3. Red manual says "IDL"

I assume:
POW= tps signal
TL= ground
IDL= 5volts


Now the automatic:
1) Green manual says Vc what is Vc???
2) Red/black manual says Vt what is Vt?
3)Red manual says IDL ???
4)Black manual says E ??

So I assumed
Vc = signal closed
Vt= signal open
IDL= 5volts
E= ground.

I connected:
From harness TPS
Green---------------------------Red black
Black----------------------------Black
REd-----------------------------Red

The MSPNP wont even start, wont sinc with my computer with the tps connected, I disconnected the TPS and it works....

Can someone please help me?
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Old 11-07-2014, 01:33 PM   #3
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you have 5v and ground reversed.
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Old 11-07-2014, 01:41 PM   #4
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thanks Brain. IDL is ground then. I will try and report back
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Old 11-07-2014, 01:47 PM   #5
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Your TPS is not wired right obviously, the signal is floating so it will constantly rise like you describe.

I found a diagram, shows 4 auto TPS wire colors. Three of them should be the normal TPS wires, and the last one is either an idle position switch, or a WOT switch.

You need a multimeter, they are cheap. Your wire colors do not match mine, so I can't help too much. If you had a meter, you could figure out what is what in 5 minutes.

Black/green is SG, Red should be WOT switch, green/white should be the signal, and red/black should be the reference 5V.

So, black/green should go to 4C/4D. Green/white should go to 4L, and red/black goes to 1N or the 5V. You need to make sure these ECU pins go to the proper place inside the MSPNP, I don't know them enough to help.

I can tell you right off rip if you've hooked anything to the red "IDL" wire it ain't right. You are probably killing the 5V reference with a direct short, which is why the thing don't start. You may have killed it even...
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Old 11-07-2014, 02:50 PM   #6
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I bought a multimeter. I did this:

"If you’re not sure which connection on your TPS goes to which wire, check it with an ohmmeter. Observe the resistance as the throttle opens and closes. Each pair of pins will behave differently:

The resistance between the 5 volt and ground pins will remain constant.

The resistance between the ground and signal pins will be low with the throttle closed and high with the throttle wide open.

The resistance between the 5 volt and signal pins will be high with the throttle closed and low with the throttle wide open.

Using these rules, you can establish which pin on the TPS goes to which wire."


So yes, I was right. On the auto tps:
Red= 5v
black=ground
red/black=signal

The car wont start nor will it upload under tuner studio... it says "off line"

This is really frustrating
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Old 11-07-2014, 02:56 PM   #7
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If I put the ohmeter between the bottom 2 pins I get a fluctuating signal.
Bottom pin and 2nd pin I get low resistance that raises when I open the throttle.
2nd pin and 3rd pin (5v) I get high resistance with throttle closed and lower when open.

1st pin I get nothing

According to diy instructions then
2nd pin = signal (red/black)
3rd pin = 5volts (red cable)
4th pin = ground (black)
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Old 11-07-2014, 03:05 PM   #8
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You are shorting 5v reference to ground, has to be what keeps the car from starting or syncing.

Are you able to find a switch on the tps? Resistance won't change, it will either be open or closed depending on if its fully open or fully closed.
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Old 11-07-2014, 03:52 PM   #9
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Ok, I was wrong. I did the testing again found this out.

Green in harness is 5v
Black in harness is tps signal
red in harness is ground

Green in vtps is 5v
red/black tps is signal
Black is ground
Red is idle

I hooked them up and the car starts again but the calibration is having the same problem were the adc keeps raising.
I going to open the megasquirt and make sure is wired correctly
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Old 11-07-2014, 04:32 PM   #10
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megasquirt looks good. Maybe the tps is the problem. I ruled everything else out
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Old 11-07-2014, 05:06 PM   #11
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Old 11-07-2014, 05:07 PM   #12
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I was just looking at the same website.
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Old 11-07-2014, 08:29 PM   #13
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Make sure your pins on the connector are free from corrosion. I just had this problem where my TPS would calibrate at one number, then would be different the next time (literally a minute later). I cleaned the corrosion off with a dremel wire wheel thing and TPS has been rock solid since.
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Old 11-07-2014, 08:46 PM   #14
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Ok ladies and gentlemen. I got it working.
I learned something, do not always trust what other people have posted.

My connections are different from anyone I know.

From harness VTPS
black-------------------------------black
red---------------------------------green
green-------------------------------black/red

Now, how do I make the acceleration enrichment wizard graph read % in the x axis instead of volts?
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