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Discussion Starter #1
I recently purchased the NX Digital Window/TPS Switch, and just got it installed this weekend. I went through the setup process, and everything went fine setting the unit.

I have a 96 Cobra, so when it came to the option to select the ignition system, I chose waste spark, which is what these cars use if I'm not mistaken. However, the RPM readings that the unit was displaying were WAY off, like showing 5000 RPM at idle, which was about 1000 on my tach. So I tried the other two options, Coil on Plug, and Distributor, to see if either of those were close. It turned out that the Distributor setting was within a few hundred RPM of my tach display, at least at idle(it showed 1100-1200 compared to 900-1000 on my tach).

Just curious if anyone has any input on this. I guess I'm concerned because the car uses a waste spark ignition (unless I've been mistaken on this), but that didn't match up with the switch. Is it different because I'm pulling the signal from the EEC as opposed to a coil pack?

Ultimately since the switch is activating and deactivating the nitrous system at set RPMs, I'm concerned about the accuracy of the RPM reading. If the Distributor setting is actually reading the exact tach signal, and my tach in the dash is a few hundred off, than no problem, but better safe than sorry. For what it's worth, I disconnected the fuel line from my nozzle, and the system did activate, but it's hard to tell the exact start and stop point from that test. Thanks for any thoughts or help.
 

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Discussion Starter #2
Update:

After some experimenting, the closest to matching my tach I can get the window switch is by using the Distributor setting on 12 cylinder mode.

Tach | Window Switch
1000 900
2000 2000
3000 3015
4000 4035
5000 5010
6000 5850

I'm tempted to say close enough, and just set the upper cut-off conservatively. But it still kind of defeats the purpose. Anyone else run into an problem like this? Would it make a difference to pull the tach signal from somewhere else?
 

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Update:

After some experimenting, the closest to matching my tach I can get the window switch is by using the Distributor setting on 12 cylinder mode.

Tach | Window Switch
1000 900
2000 2000
3000 3015
4000 4035
5000 5010
6000 5850

I'm tempted to say close enough, and just set the upper cut-off conservatively. But it still kind of defeats the purpose. Anyone else run into an problem like this? Would it make a difference to pull the tach signal from somewhere else?

That is the setting you will want to use. There's no telling if there is a little discrepancy between the tach and the box, but that's so close it won't hurt anything.

Thanks,
Garrett
 

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That is the setting you will want to use. There's no telling if there is a little discrepancy between the tach and the box, but that's so close it won't hurt anything.

Thanks,
Garrett
95sixstang did you ever get this straightened out? I am running the same switch and for a whole year it worked great, then all of the sudden the RPMs bounce all over the place and are NO WHERE close to the correct RPMs. It bounces to 5k,3k,2k,5k, then for a split second will hit the correct RPM then back to bouncing again. I haven't touched anything and I have reprogrammed it several times. It works as soon as the car is started and then about 20 seconds in starts bouncing.
Its aggravating!
 
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