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Old 03-23-2016, 10:25 PM   #1
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Default TPS problem 94 chassis

Hey guys so I have a 1994 Miata chassis with an NB engine. I am trying to calibrate the TPS with the 94-95 mspnpv2 and it is reading too high (1023).

I have an 99/00 skunk2 throttle body and I am using an NB tps (I believe the 94 TPS harness will not plug into the NB tps?)

I followed this reference and tested the harness if it is receiving the correct amount of voltage. The harness is receiving the right amount of voltage:

The 1994-1997 chassis did come with a 0-5v variable TPS. It is a standard 3-wire TPS with an additional fourth wire (red) which serves as a wide-open switch. Your standalone ECU will likely not use this fourth wire, so if you are changing the pigtail to a 99-05 style, simply heat-shrink over this unused wire. If you are using your 94-97 throttle body, there are no wiring changes necessary. If you are using the 99-05 sensor, wiring colors are listed below:

5v Reference:
94-05: Light Green/Red

Signal:
94-97: Red/Black
99-05: Green/Black

Ground:
94-97: Black/Blue
99-05: Black/Red

https://www.miataturbo.net/engine-pe...athread-80469/

Another question, I have 2 mspnpv2's. Can I simply use my 92 mspnpv2 on my 94 chassis? The 92 mspnp has my original map.
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Old 03-24-2016, 01:18 AM   #2
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92 MSPNP won't work in the 94 without a patch harness, the pinouts are different.

If you let your car sit for a few hours, is the TPS immediately at 1023? I ask because a grounding issue would cause the TPS signal to go from 0 to 1023 slowly after you turn the key on. Let your car sit overnight and check the TPS signal immediately when you key the car to ON.
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Old 03-24-2016, 02:52 AM   #3
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Quote:
Originally Posted by Onyxyth View Post
92 MSPNP won't work in the 94 without a patch harness, the pinouts are different.

If you let your car sit for a few hours, is the TPS immediately at 1023? I ask because a grounding issue would cause the TPS signal to go from 0 to 1023 slowly after you turn the key on. Let your car sit overnight and check the TPS signal immediately when you key the car to ON.
Hey Onyx, thank you for the reply! I'm not sure if it's a grounding issue. When I checked each pin on the tps harness plug, it read 12v, 5v, and 0 (ground).

The TPS showed 1023 at no throttle and at WOT throttle. I assumed it was the tps so I was tapping it to see if it made a difference.. it stayed the same.

The TPS was fine when I pulled it from the other 92 shell.

When I tried starting it, megasquirt was showing me that the rpms were not kicking either.
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Old 03-24-2016, 03:03 AM   #4
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I forgot to mention, I used a speaker wire to jump the tps and car has no spark now...

Last edited by AdoboMiata; 03-24-2016 at 03:22 AM.
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Old 03-24-2016, 01:15 PM   #5
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your wiring created a 5v fault to ground.

this may help you (this is a 1.6L reference doc):

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TPS problem 94 chassis-80-blob_3c31a93d264e221b0556501e18b159422e3e9c61.png  
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Old 03-24-2016, 02:36 PM   #6
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Quote:
Originally Posted by Braineack View Post
your wiring created a 5v fault to ground.

this may help you (this is a 1.6L reference doc):

Thanks Brain, I will report back
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Old 03-24-2016, 02:55 PM   #7
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Updaate:

I downloaded the new mS2/Extra 3.4.1 release Firmware from Megasquirt Downloads Firmware and Software - Megasquirt EFI

Car is reading tps even though I do not have a jumper on it. I was able to calibrate it without any jumper.. odd..

I calibrated the IAT, Injectors, wideband, and set the timing to 4g63. I am receiving no spark. I do have fuel ( I can hear the pump priming at key on)..

I attached my MSQ file and a composite logger. fyi, I am not sure if I did the composite logger correctly, but I'll do it again if necessary.

Last edited by AdoboMiata; 03-24-2016 at 10:01 PM.
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Old 03-24-2016, 03:02 PM   #8
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second log. Cranking, then after a few cranks it would stop..
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File Type: csv compositelogger3242016.csv (19.7 KB, 21 views)
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Old 03-24-2016, 04:58 PM   #9
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changed cas... tried to start it, heard a loud "poof" sound and still doesn't start.
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