MikeSVT04

I have an nx tps/rpm window switch and an nx 90mm plate kit with nano.FRPS installed on the rail.

I went to get the setup tuned yesterday and set the window at 3k-6500rpm at wot. During the pull it turned off and on. At 2k rpm it turned on then off. then on and again at 2.5k then off. then back on at 3k all the way to 5.5k then shut off then back on at 6k until 6500.

This was repeated several times same outcome. Tuner believes it's getting a bad rpm signal causing the rpm signal to jump around.

I watched the controller, and it never turned off throughout the run, but the nitrous went off and on.

I'm going to check the rpm wire this weekend, but any other ideas would be welcome.

It did make 560hp-565tq on a 100 **** when it worked. Baseline was 460-420. I'll try and upload my dyno sheet to show where it shuts off exactly.

Thanks,

Mike



​​​​​​green line is 50 shot....

0NitrousOutlet

Are you logging fuel pressure? Can you tell us more about your set up? Motor, fuel supply etc.

MikeSVT04

Yea, sorry. C6 gs mn6. Texas speed 229/236 cam full bolt ons. I have a boost a kb pump wired to come on when the nitrous hits. Fuel pressure is great the whole run/ slightly lean on the hit. Injectors are at 77%.

MikeSVT04

Update, for future reference if you have the same issue. Rpm signal was weak. Wire was resoldered​ and she is working perfectly.

Frans96ss

Its the FPS switch.... they are junk... take it off. When the nitrous sprays the FP drops bc the stock pump cant hold the pressure like that so it turns off... builds pressure back up... sprays... drops pressure etc.

Turbo2L

This. I would also have the BAP on prior to the hit to better stabilize FP, but that's just me.

CI GS

I would re-wire the BAP to turn on when the N2O system is armed, not when it's activated.
You can use a Hobbs switch as a fail safe FPSS, but you will have to adjust the shut-off pressure quite a bit lower (maybe ~48psi) than the normal rail pressure (58psi) to keep the fuel pressure drop at the rail from shutting it down when pressure drops on the hit, as Fran mentioned already.
If you were able to monitor fuel pressure you would be able to easily diagnose what's happening during a run with the nitrous on and set your Hobbs switch accordingly. It's too bad that these cars didn't come with the ability to read fuel pressure.