MSPNP2 Throttle position sensor issue

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moresmallerbear
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MSPNP2 Throttle position sensor issue

Post by moresmallerbear »

So, purchased and tried to install the MSPNP2 this weekend. Found some setup instructions, had to fudge and research others. Everything seems to be reading OK, save for the throttle position sensor.

Tested the connector for 5v reference and ground, tested the ECU pin for signal to ensure continuity. Tested the sensor, it runs 1.6-9.5k ohms, which seems to be about normal for these as far as I can tell.

Megasquirt reads the sensor at ~40% at all times. No matter if it is connected or not. I have not been able to find any sort of calibration besides the upper and lower limit one.

The only thing I can imagine is happening, is the megasquirt itself is reading from the wrong pin, and getting a constant voltage. I have not been able to find anything but option pinouts in tuner studio, so I can't verify which pin its actually reading from. Anyone else had this issue?

EDIT: Forgot to mention. 1991 240sx, KA24DE. Also, the engine bay grounds have all been cleaned.
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BigLoukaT
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Re: MSPNP2 Throttle position sensor issue

Post by BigLoukaT »

I have previously had some issues with the tps sensor reading when I hadn't tightened the ecu connector down tight enough.

You can look at a dohc fsm to find the right tps signal pin, and measure the corresponding pin on the mspnp mainboard. See if you're getting some voltage at closed throttle (hopefully around .5v) and some other voltage at wot (probably around 4v). Actually voltage doesn't matter much since the ms will set according to your calibration, but you do want consistent results.

Have you calibrated the tps?

Do the ADC counts change when you go from closed throttle to open throttle?
1990 S13
Boosted single slammer
MS DIYPNP
npx from 240sxforums wrote:i figure from my very limited knowledge about the 240 and under the hood about cars in general i would follow the sr20det trend.
moresmallerbear
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Re: MSPNP2 Throttle position sensor issue

Post by moresmallerbear »

No, the ADC count does not change on calibration. I tested the pin on the connector, getting the appropriate voltage from the TPS.

Contacted DIY auto tune, they are taking care of it under warranty. I think that the car interface was connected to a different pin than expected on the megasquirt, as it would read a constant 40 percent throttle no matter input.
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headfirst427
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Re: MSPNP2 Throttle position sensor issue

Post by headfirst427 »

Hey moresmallerbear, what ever happened with this? I just opened my MSPNP2 box today and jumped Serial Port 9 to power my blutooth adapter. Since I've done this I'm getting a constant -14.8% throttle input. Was not like this before the 5v was turned on. Car will start but will not idle without constant throttle input.
1995 KA-T S14
255whp / 270tq
Megasquirt PNP Gen 2
ISR Performance RS3871 Turbo
ISR Performance V2 Manifold
Five-O 550cc Injectors
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