Ok, So I was speaking with a Nissan Mechanic who i have know for years, and even use to work with, and I was showing him i dyno of my car I had done when i first got the car, baseline and this y-pipe/cat combo I tried back in the day. I noted that in both cases, the first run produced rich fuel curves and that got the his mind going. He said back in the day of the earlier z's, i easy way to add some fuel was to wire in a varible resistor to the cooling sensor, and as the car warms up, you could increase the resistance, which inturn changes the way the ecu throws fuel at the car. Now I have done some research, check out page 199 in the service manual, you'll see what i'm talking about. Unfortunetly I do not have wideband o2's or that apexi thing to monitor the fuel curve. But this a cheap and interesting thing to try, i just can not verify the results at this point. He also said the var-res could be mount in the interior so changes could be done on the fly.

 

so basically... what are you trying to say? this sounds interesting

 

an easy way to adjust A/F :P

lets see if there is any truth to this urban legend haha

 

i doubt it would work. the coolant temp senseor only comes into play b4 startup and durring warm up after that the computer goes into closed loop and runs off the o2's to determine fuel if anything that would probably kick the car out of closed look and make it use more gas

 

I'm am not familiar with how the ecu operates, but hoping to learn. I'm not sure if you have a copy of the service manual, but page 134 of section EC has a nice flow chart, also states "not nessasary when open loop at low engine coolant" That would lead me to believe that it does play a role in closed loop, higher coolant temps.

 

I'll agree with the closed loop theory. If it does work it would likely come out of closed loop and use more of your $3/gal gas

However, I'm curious to know the results, maybe you'll prove us all wrong.

 

ok, but according to my dynos, it was getting leaner, so in my case, more fuel = more power. And since you can control it, you control when and where you are adding fuel. and not sure of it coming out of closed loop, due to the range of resistance that could be adjusted to, say the resistance at 165 degrees vs 195.

 

yea i understand that you want to add fuel but if you come out of closed loop your timing is going to change and you will end up loosing h/p. I dont know what would happen if the comp jumped into open loop under full boostt but i could imagine either way it wouldnt be benificial.

 

1. yes it works...the NISMO thermostat on my car causes my car to run richer than my original dyunos, which were done pre thermostat

2. causes a CEL - the ecu knows the temperature the thermostat gets to when it opens, and knows how long that should take given the outside air temps...if it takes too long, or too short, bingo, CEL

 

"causes a CEL - the ecu knows the temperature the thermostat gets to when it opens, and knows how long that should take given the outside air temps...if it takes too long, or too short, bingo, CEL"

But since the driver would have control of when the resistance is increased, could the cel be avoided by waiting till operating temps are reached? I Was told that is was not always meant to be turn on so to say, but when conditions are met, and for use say on the track or at the strip....

 

well, the question that begs asking is what on earth is done to your NA Z that you need to add fuel?

But beyond that, if you are game to sit there with a datalogger and figure out the precise threshold of resistance that it would take to trigger the CEL, at every conceivable outside air temperature, then you have way too much time on your hands

I would spend the $$ on getting a dyno tuned reflash

 

If the fuel curve didn't need to be adjusted, then why would you get a reflash? According to my old dyno, in each case when the car was cooler, the run made more power, and the fuel curve was learner on the warmer runs.....I am nearly trying to find an inexpensive solution for the problem of the 350z getting leaner with mods. Is this not benificial?

 

Not always true!!!!!! richer can mean slower and sluggish just depends on the tune. These cars stock like to run lean!!

 

I would not take the results of one dyno session as being gospel. I have noticed the total opposite with the car...the more successive runs I do, the more power and torque the car nets due to it's adaptive ecu. That is until the intake manifold heat soaks sufficiently that power falls off. Even then, I have not seen significant drops in my pwoer figures (maybe 5-6 whp).

Reflashing does alot more than altering the fuel curve...again, the results vary from car to car, but on mine timing as well as fuel was altered, as well as increased rev limited and no top speed limit.

Even with my mods, the car still runs richer than is optimal, but given the finicky nature of the ecu, my car is very consistent day to day, even nearly 2 years after my flash was done

 

if they come lean and run lean, that is great, adding mods and making leaner might not be so good, correct? And i'm not say a reflash is a bad thing, and I understand what can be done, as I have had great success with previous vehicles and chips. It is something that i would like to do, but it is expensive. The mechanic did not say it would work for sure, but I thought I would share this topic in hopes we could all gain something from it.

 

Yes once you get out of the factory set perameters then yes something else will need to be done but as Z1 pointed out there is alot more involved than just adding fuel.

Think about this if you make the ECU think that the engine is running cooler than it really is what else is it gonna do? It's gonna advance timing as well so if your engine is running warm and you advance timing and add a little fuel you may be safe but you may even go leaner because of the increase temps!!!

There are alot of things to concider

 

I definetly agree, that's why I was hoping to get someone with some sort of a/f gauge to help out or try it or even a dyno run, just to see what effects it has. Like I said, if it work to some extent, it could be used for maybe runs at the strip or something more. If not, it's not a permenat mod, but seen many people spend $$ in hopes of a few hp (myself included).

 

Is this what you're looking for?
http://cgi.ebay.com/ebaymotors/NISSA...QQcmdZViewItem

 

just get a SAFC if all you are looking to do is get the car richer...it will allow small weaks to your fuel curve. However, realize that as you alter fuel tables you also alter timing tables