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Just got my car road tuned before the dyno with 740cc deatchwerks, in hind sight they might have been too big for my application (rb25 neo with 250kw highflow)

I went from a crappy magnaflow reg with 440cs to a stock rail, reg with the 740s and the car started stone cold first go, ironically it idled and low load was actually better with it untuned than it ever used to be, starts every time with no throttle.

Anyway got Pete at Nistune to do a road tune with them to make sure there weren't any major issues before the dyno, unfortunately due to their size we had to play with the k factor a fair bit to get enough resolution to get the AFRs above 10:1 in the top end, this in turn meant my idle and low load suffered a bit, though with lots of tweaking the latency and making sure the O2 was set up correctly got it as good as it was before, able to mantain stoich idle and get it up to 11.5:1 in the top end with enough resolution to still tweak it further.

The real test will be when we get it properly tuned on the dyno and see what sort of economy I get, it is fairly poor at the moment but the tune was just a "good enough" one before getting on the dyno.

Pete was very sceptical of them being able to work with the nistune and get the low load/idle/cold start working properly but when he saw how well they worked was quite surprised, even more so that they worked with no tweaking at all from my previous setup. Will report back when I get the full tune done and do some testing to see what fuel economy is like.

Edited by Rolls
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Getting ~14-15L/100km city driving with a good enough tune, better than with GTR injectors as I was getting closer to 16 and the same driving style

gets properly tuned tonight, will see if it improves.

Edited by Rolls

I only have 555cc nismo injectors, but I get like 9L /100km according to my ecutalk consult display and nistuned z32 ecu.

I was always under the impression if you get a full tune (not just 4th gear power runs) then you should get reasonable economy regardless of injector size. Obviously the bigger the injector the harder it will be to have good economy on light loads though.

Have I been under the wrong impression?

Depends on the injectors minimum pulse width. My min pulse width is smaller with DW 600cc than the stock inj minimum, so it negates any idea that they won't cruise or idle on stoich. Don't know about the 1000/2000s.

Also, I don't know how your cars tuned Mitch, but I've found that the trip computer economy goes out the window if you change injectors because you also change the K constant. E.g, my car now thinks I can do 1000kms on a tank because My k constant almost halved within the factory ECU. Its obviously not going to do 1000km on a tank any time soon!

Depends on the injectors minimum pulse width. My min pulse width is smaller with DW 600cc than the stock inj minimum, so it negates any idea that they won't cruise or idle on stoich. Don't know about the 1000/2000s.

Also, I don't know how your cars tuned Mitch, but I've found that the trip computer economy goes out the window if you change injectors because you also change the K constant. E.g, my car now thinks I can do 1000kms on a tank because My k constant almost halved within the factory ECU. Its obviously not going to do 1000km on a tank any time soon!

I was just quoting what my ecu consult display says. I think it should be reasonably accurate though, because my nistuned z32 ecu still supports consult and the nistune daughterboard adjusts all the values to suit everything before being read at the consult port.

But it could be wrong as well. Pre tune on stock setup I was getting about 450km per tank running it down to just before the fuel light.

So far I have done 300km and still have a bit less than half a tank.

I was just quoting what my ecu consult display says. I think it should be reasonably accurate though, because my nistuned z32 ecu still supports consult and the nistune daughterboard adjusts all the values to suit everything before being read at the consult port.

But it could be wrong as well. Pre tune on stock setup I was getting about 450km per tank running it down to just before the fuel light.

So far I have done 300km and still have a bit less than half a tank.

Lol are you ever on boost?

I was just quoting what my ecu consult display says. I think it should be reasonably accurate though, because my nistuned z32 ecu still supports consult and the nistune daughterboard adjusts all the values to suit everything before being read at the consult port.

But it could be wrong as well. Pre tune on stock setup I was getting about 450km per tank running it down to just before the fuel light.

So far I have done 300km and still have a bit less than half a tank.

It doesn't adjust the fuel figures, ignore them and work it out properly, there is not way you get 9L/100km

do it the way everyone else does, run to empty, full tank, reset odo, run to empty, divide litres used / odo * 100

Edited by Rolls

Lol, you wish sunshine, unless youre on the highway the whole time or you don't boost, ever!

I'm not gonna argue with people about it, because it's so trivial. I'm open to the fact the ecutalk consult might not be right with econom calculations now, but I know how far I travel on each tank and how much fuel the car takes when I go to fill it up. Canberra doesn't have crazy traffic though, its pretty open, so that could be part of it.

Edited by Mitcho_7

You may get a reading of 9L per 100km at one particular point in time but that is not the same as an actual average consumption figure. Km per tank are not accurate you need to measure the fuel used for a given number of km and do the calculation.

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