GTi-R ECU fuel tables.

Fusion Ed

Fusion Ed

Active Member
I just thought I would show why the GTi-R over fuels so badly when it is taken beyond its factory settings. This applies to anyone really thats running more than 1 bar boost with no remaps etc..



This above image is the target fuel map for a stock unmodified GTiR ECU. The values are the target AFR's the highlighted area is the area in which the lambda sensor will be in closed loop.

As you can see as you tend towards the far right, which will be reached by higher boosts etc, you will start to get into areas of the table that are ridiculously rich. Soon I will have data of how far the GTiR ecu goes standard (to do that I need a totally stock GTi-R which are getting harder to find! Then I shall compare this against a lightly modded 1.2 bar GTi-R which I consider is beyond a safe limit with no ECU modifications, as I have said in the past it may work but this table shows just how far from ideal it is.

Ed
 
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nickr

New Member
Do you have a optimized fuel map for a 1 bar gti-r with a filter, downpipe, decat, exhaust, std turbo?
 
PaulB

PaulB

Member
nice one ed.

So from that im guessing anything in the 10`s in silly rich ? Is this simply because the factory hasnt any proper values to refer to when you up the boost? I know when you up the boost, fuel pressure rises in line with it, is this the reason why its rich as the ecu cant limit the injectors, and opens/closes as if on a lower fuel pressure, therefore more flow ??

If that makes sense ! lol

Now that my car is on the road, il put my datalogger on and show you mine, with the 1.4bar, Q45 and 550`s.
 
Fusion Ed

Fusion Ed

Active Member
Mark, yes that may be the case, you probably went beyond 100% and so started to lean back out again (if stock anyway). So it will then begin to lean out, to the point were it will get too lean and things will go badly wrong. Some gtir ecus seem to cut out, others not. if you get into the red cells.

Paul, Yes anything in the 10s is a complete waste of fuel and will result in a loss of power and very high CO and HC exhaust emissions.

Please bear in mind that this applies mostly to totally standard cars but with say fmic airfilter and 1bar +
 
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nickr

New Member
would be interested in purchasing your services or a bin file off you if u could put one together... removing the speed limiter would be nice too
 
Fusion Ed

Fusion Ed

Active Member
I am able to supply at some point in the very near future programmed ROMs you would need a daughter board however to fit them. Removing the limiter would be simple, but again not all pulsars seem to have them. Do you have consult? are you able to send me a rom dump to have a look at?
 
Fusion Ed

Fusion Ed

Active Member
Beyond 100% i mean that say you hit x boost and rpm. The ECU can fuel for this but then suppose you go beyond x. The car will still fuel etc but its already at 100% so the only option is for it to lean out again.

The impression this would give for example on a rolling road is you had a rich midrange and an ok bottom and top end. Where as in fact, the ecu would be fueling fine initally then go rich where you went beyond the stock mapping, then anyfurther than this it would then be leaning out again.
 
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pulsarboby

Guest
so in other words the injectors would have maxed out and not supply enough fuel beyond that point!
but prior to that around 1 bar with standard ecu they would be running rich due to the fuel pressure regulator?
is that right what im saying?
 
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MarkTurbo

Well-Known Member
I still dont understand :lol:

I always like to over simplify things so say for instance at 1.4/1.5 bar, maf isnt maxxing out, injectors arent maxxing out either. So forget revs and boost for a minute unless you hit the limit of the maf/injectors what is there that would make it run lean :?
 
Fast Guy

Fast Guy

Moderators
Staff member
What happens above 6800? The redline is 7500+, so I assume the factory ECU must be mapped to this rpm.

What boost level is that map for, as it needs some sort of airflow reference to be of any use. The MAF must play a part somewhere.
Now I assume there's a map for several levels of boost, so surely when the engine is overfuelling so much at high boost, unless the ECU has something in it saying "boost is too high, lean the fuel and try and blow the engine" the only time it will start leaning out is when too much air for the available fuel is being put into the engine? Either when something has already maxxed out or a bigger turbo is fitted and running more air than the available fuel can cope with?

How does the FPR cope with all this. It runs at boost+43.5psi, is there a top limit it won't go above? Otherwise wont it keep raising the fuel pressure and keep adding more fuel even when things are maxed out (until an injector fails or something)?
 
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micra_pete

Guest
ed, for info at wot, in general, all nissan ecus will use the last two columns, its just the way the standard ecu is set up.

you will find with higher boost your final tp gets higher, this is why we expand the maps on the stock ecu for cars running higher boost than normal.

by expand you shift everything over a column so you can use a higher tp value in that last column - if that makes sense.

fast guy, over 6500rpm the ecu, in general, will use that last column as its reference until the redline,the map is for a stock gtir.

not teaching grannies to suck eggs here, just hoping to help :)
 
Fusion Ed

Fusion Ed

Active Member
Essentially rescaling the maps. Which is exactly what you do when mapping other ecus.

What boost level is that map for, as it needs some sort of airflow reference to be of any use. The MAF must play a part somewhere.,
Click to expand...
Fastguy. The car does not know boost. In fact the ECCS system does not even care about boost. The main load sensor is airflow, which is directly related to rpm and boost. Load is shown along the graph horizontally, shown from 9-86. If you run more boost then your ecu will see that as more airflow and thus higher load.

Now I assume there's a map for several levels of boost surely when the engine is overfuelling so much at high boost, unless the ECU has something in it saying "boost is too high, lean the fuel and try and blow the engine"
Click to expand...
As above, no its all based on airflow and RPM.

the only time it will start leaning out is when too much air for the available fuel is being put into the engine? Either when something has already maxxed out or a bigger turbo is fitted and running more air than the available fuel can cope with?
Click to expand...
Yes exactly, which happens when you start running more boost, when you are already at say 100% injector duty, and then you will start to go leaner as the ratio between air and fuel becomes greater.

How does the FPR cope with all this. It runs at boost+43.5psi, is there a top limit it won't go above? Otherwise wont it keep raising the fuel pressure and keep adding more fuel even when things are maxed out (until an injector fails or something)?
Click to expand...
The FPRs job as you will know (but im saying this for others who wont) is to keep the fuel pressure ALWAYS at 3bar above intake manifold pressure. This pressure is chosen to enable decent atomisation and flow. The limit of the FPR is more to do with the fuel pump. If you have a fuel pump that can flow enough fuel to make what power you want at say 5 bar railpressure, you can then run upto 2 bar boost (keeping the 3 bar difference) and everything will be fine. If you had a pump that could only goto 4 bar or had a low flow rate as boost increased the fuel flow would drop to the point where fuel rail pressure could not be maintained and you would then as a result run lean. The limit of this is down to the pumps ability to flow at high pressures and in very high powers the pipework and ability of the fpr to deal with the return flow back to the tank when at low duty cycles etc..
This system must be considered separately from the ECU. They are independent systems, however the ECU is able to trim its base AFR using lambda feedback to trim for minor changes in fuel quality/pressure etc..
 
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micra_pete

Guest
yep, the point about rescaling was only to explain what i meant with the postion on the map at different boost levels, which you were wondering about in the first post :)
 
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micra_pete

Guest
ed, re-reading my posts it reads like im telling you how about expanding maps, apologies if thats how it comes across.

As you can see as you tend towards the far right, which will be reached by higher boosts etc, you will start to get into areas of the table that are ridiculously rich. Soon I will have data of how far the GTiR ecu goes standard (to do that I need a totally stock GTi-R which are getting harder to find! Then I shall compare this against a lightly modded 1.2 bar GTi-R which I consider is beyond a safe limit with no ECU modifications, as I have said in the past it may work but this table shows just how far from ideal it is

its this i am attempting - not very well - to explain.

at wot or close, whether the car is stock or running silly boost you will find yourself in the last one / two columns, its just the way nissan ecu's work.

its the final tp you need to be comparing, and see how much higher over stock you are.

hope thats a little clearer.

again not teaching granny to suck eggs
 
fubar andy

fubar andy

Moderator & N/W Rep
Staff member
Micra Ed said:
Yes exactly, which happens when you start running more boost, when you are already at say 100% injector duty, and then you will start to go leaner as the ratio between air and fuel becomes greater.
Click to expand...
Would this cause a standard rnn14 ecu to cut the fuel to the engine?

As you’ve posted this a friend of mine has hooked up the “consult” programme to my GTiR today and we have been trying to work out why my car keeps cutting out under load at high revs over 6800rpm and over 130mph in 5th.

Unfortuanlty the programme is limited towards the rnn14 ecu, but in the next month or so, we are looking to add potential programmes to assist in tracking down this problem.

However what is more important to me is that you mentioned that:

Micra Ed said:
this applies mostly to totally standard cars but with say fmic airfilter and 1bar +
Click to expand...
and

Micra Ed said:
you probably went beyond 100% and so started to lean back out again (if stock anyway). So it will then begin to lean out, to the point were it will get too lean and things will go badly wrong. Some GTiR ecu's seem to cut out, others not.
Click to expand...

Although I’m under a bar (0.8 – 0.9) would this still be detrimental towards the ecu and possible problem of which is the cause of my engine/fuel cut when driving hard?

At the moment i’m in the process of changing my sparks, dizzy and rota, but I have the feeling that this will do no good. I have also installed an uprated fuel pump, but to no avail. :?

Any sort of information that you can shed on this or ideas you may have would be a real help at this time
 
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