Thanks UltraGauge, screw u Nissan.

[Red_Liner740]

So today i mounted my freshly received Ultraguage....and was eager to test out my MPG and hypermilling work AND to test out my newly installed kill switch and button start (no fumbling with the ignition anymore )

so problem number one. Killing the engine with the kill switch, even though the speedo still shows speed and my odo keeps reading clicks, kills the ultragauge. I thought maybe i can do something with that but as of now i'm probably gonna change how the kill switch turns off the engine.

Problem number two. To my horrible amazement and piss off factor aimed at Nissan, even with the car fully warmed up and been driven for 30 min or so, if i kill the car, and restart it, the MOFO goes into open loop for 3 or so minutes....so all that fuel i just "saved" by turning off the car is wasted by higher fuel consumption during driving and the worst part, loss of DFCO!! Thats right, with the engine in open loop the engine doesnt turn off the injectors, in fact, as the rpm climbs as i downshift it actually dumps more fuel in!

So WTF do i do? any pointers?

The car in question is a 2001 Nissan Maxima SE 20th Anniv Ed.

On a positive note, one more good point for getting an ultragauge or scangauge....had i not gotten it i'd be sitting there like an idiot with a grin on my face turning off the car at lights meanwhile i was probably burning more fuel than just letting it idle.

[phunky.buddha]

Wire up your kill switch to turn off the main relay or whatever controls your injectors directly? Find a way to keep the ECU alive but the injectors off? Interrupt the FI fuse line?

[SentraSE-R]

Red liner,

Unfortunately, I can confirm your observations with my 2002 Nissan Sentra SE-R. If I shut the engine off on a long downhill coast, it took a full four minutes in open loop for the ECU to decide to return to closed loop again, Even when it went into DFCO, Nissan programmed DFCO to occur only when the engine was >2500 rpm. In effect, only when traveling faster than 65 mph in top gear. For comparison, my Scion xB enters DFCO when rpms are >1500 - 35 mph in top gear, and the Scion stays in closed loop after it's been shut off and turned back on again.

On the good side, I actually kept and maintained a higher lifetime hypermiling % above EPA combined fuel economy estimates with my Nissan (170%) than I've managed with my Scion (167%), and I put about 20,000 miles on each. I suspect that running in open loop isn't as awful for fuel economy as it seems to be in theory. I managed 60 mpg EOC P&G 20 mile test drives with the relatively thirsty 170 hp 2.5 liter engine running in open loop.

[mcmancuso]

Yes, wire the kill switch into the fuel injector relay and not the ignition, most cars will go into open loop if you shut down the ECU. The secondary benefit of this change is that you can force DFCO down to 1K RPM or wherever you like.