Tuning Rb25S For Eflex And E85 .

[rob82]

You can adjust target lambda in datalogit, I wouldnt recommend using the innovate for the feedback, as they have a very poor reputation for reliability

How do you change the target lambda in datalogit? Are you referring to o2 feedback lambda?

[Dose Pipe Sutututu]

How do you change the target lambda in datalogit? Are you referring to o2 feedback lambda?

I don't remember seeing any target a/f.. just only the check box for O2 Feedback

[Race__24]

I don't remember seeing any target a/f.. just only the check box for O2 Feedback

Can you set up a wideband with the power fc? If not you won't be able to adjust the feedback as this is determined by the O2 sensor

[Dose Pipe Sutututu]

Can you set up a wideband with the power fc? If not you won't be able to adjust the feedback as this is determined by the O2 sensor

only narrow for the O2 feedback.. you only can connect the wideband channel to datalogit kit for mapping

[discopotato03]

I'm going to find out for sure how much fuel I can squeese into my R33 this afternoon because ATM its low enough for it to lose power because it was nearly out . For some silly reason the the spring loaded fuel socket flap fell into the tank a week or so ago and this time around the low fuel light didn't come on .

I must have driven 60 or 70 km below the E line and was part way down the E itself before it gave signs of starvation . I was carrying some E70 in containers because one thing you can't do is get low on this fuel when it isn't available everywhere .

At least I know now how low I can get via the gauge and that will help me estimate what mileage I'm getting . I'll check it at 1/4 1/2 and 3/4 to see if the gauge is accurate , 55 divide 4 = 13.75 so the quarters shoud be 13.75L - 27.5L - 41.25L and 55L . By my estimations I've been getting around 14/100 which is sort of ok in a car thats not properly tuned and has some sensor issues . This is mostly around town driving too .

A .

[GTSBoy]

You can't really treat the gauge that way though. Generally in a Skyline you can get about 50-70km out of a full tank before the gauge drops to the F line. Then depending on the exact car, you might get 30-50 before it drops to 3/4, or you might get 100 before it gets there. Some cars will show 1/2 at 200 or so km, some will get to nearly 300. And some will drop from the 1/4 mark to E in only 20km. All of this somewhat independent of exactly how much fuel the car actually uses too.

[discopotato03]

Thats why I want to fill it 13.75L , 1/4 tank , at a time to see what my gauge reads .

A .

[discopotato03]

After going backwards consumption wise I'm getting better results with slightly richer and more advanced settings at around town revs .

I am curious to know if anyone worked out the ideal injector lag time because searching gives all kinds of numbers ie from 0.08 from the SR people to 0.20 from some RB people . Mine is currently at at 0.14 but I did try 0.08 at hot idle and it sent the mixture leaner , 0.16 made it rcher .

I would have thought that anything other than injecting more fuel that made mixtures richer was a step in the right direction because it sounds like what fuel going in is being burnt more efficiently , could in theory go this way and inject slightly less fuel for the same mixture result ?

I always though sequential injection and having control over injection timing only made a difference up to say 3000+ revs and then the speed of the cycles and inlet air overcame any injection timing differences .

Also something else and yes I did search forst .

Are the battery voltage corections in the sample Datalogit RB25DET dat file the right ones for 740 Nismo side feeds because that could be one variable that people may not be taking into account . Datalogit shows that my running voltages are mostly between 14 and 14.2 volts but on a log it once spiked to a 14.6 max .

Any help appreciated , cheers A .

Actually one more I entered 10 10 and 8 in the retard from coolant temp settings and I think its warming up faster because of this . I may try 12 12 and 10 next .

Edited November 6, 2012 by discopotato03

[GTSBoy]

The lag time is a property of the actual injector you are using, not something that you fiddle with at random.

[discopotato03]

I will agree that there is a fixed time between injector closed and opened but I don't agree that applying a set correction has to be cast in concrete . How would we know why Nissan set up their sequential injection timing where they did with standard parts .

Anyway obviously moving the correction number around changes the injection timing which in turn can change the AFR - mine did any way .

I think the reason why Apexi allow corrections is to make the altered injectors partially mimic what the standard ones do as in the start or finish of the injection pulse .

I mentioned before that I played with an Autronic SMC years ago and moving the injection timing around made changes , I just didn't know how much because I didn't have access to a wide band 02 reader like I have now .

I suspect that the part of the injection pulse that we are correcting for is the closing phase or end of pulse because that is the part in the engines cycle when all the fuel has been added . To me it makes sense that a larger injector will be open for a shorter period that a smaller one to inject the same amount of fuel and if the end of pulse occurs at the same point in the 720 degree cycle (four stroke two complete revolutions per cycle)then the effective AFR should be the same .

What I want to know is why the AFR changes with injection timing , particularly if the pulse width (injector open time) remains the same . Logically if this occurs at idle the injection timing must have been wrong to start with . You would think that moving the injection timing around so that the least pulse that gave the intended AFR should be best - why inject any more fuel than necessary to achieve the desired result .

Without meaning to sound insulting it looks like some fiddle with correction numbers but may not have the means to see whats actually going on except noting the engine running rough or lumpy from the mixture going lean or rich .

I think an idling engine has to have everything right to idle well as in ignition timing injection timing and obviously AFR . Its being literally strangled by the throttle/s and its effective CR is very low , to try to have efficient combustion with such little air probably creates narrow windows of opportunity to inject and fire what mixture it has .

Anyway AFAIK injection timing in sequential systems seems to have the greatest effct on the slowest engine speeds and the accuracy advantages fall away with increased engine speeds . In fact I believe some computers are designed to revert from sequential to batch fire above a certain engine speed because its no longer important - and injecting twice per cycle in batch mode rather than once per cycle in sequential mode can reduce the need to use large injectors to start with .

All this aside I found a not insignificant fuel leak below my fuel filter yesterday and having fixed that I should get better consumption figures ! Being on the pump side of the reg it may have in some small way affected fuel pressure and more so at elevated manifold pressures . I reckon I can feel some slight differences and the Tech Edge is showing slightly richer mixtures under load .

Always a worry to find fuel pooling under your car , cheers A .

Edited November 7, 2012 by discopotato03

[GTSBoy]

I have not read past your first paragraph.

NO. The latency needs to be approximately correctly set for the actual injector because if you have it set far away from what it really is then you will have to correct either the idle or the high load injection pulsewidths to compensate. If you do not know how Nissan's ECU (and by extension, the PowerFC seeing as it's basically a copy) calculates injection time and uses the latency time in that calculation, then I suggest you actually go and find out. Read the Nistune documentation, for example.

[discopotato03]

GTS boy I am aware of what goes into calculating injector pulse width and why . You should have read my whole post because then you have some idea where my questions are - not just blatently brush me off .

A .

[GTSBoy]

I needed to leave for work. Your first para said "how would we know......." which implied that we don't know, which we do.

The latency is one thing. Injection time (as per your discussion on Autronic) is a completely different thing. Not to be confused. Sure, moving the injection event around with respect to the valve opening can and will have effects. No argument. But changing the latency has nothing to do with that. The latency is a fixed number of microseconds that you need to subtract (or add to, depending on which end of the calculation you're starting from) the injection time to allow for the time when the injector is energised but not flowing. This is not something that offers any avenue for tuning, except to set it to the value it is supposed to be.

[simpletool]

Here's my 2cents. I could be wrong but I always thought is was (injection time + latency) = pulse width. Therefore the 2 are very closely linked. Latency affects both start time, and length of time. Latency is a small number so it really only affects idle and low loads, on/off throttle response.

Whether something is 0.8ms or 1.2ms will make a difference but it's not going to make a huge difference when you are running 25+% duty cycle (10% relative difference in mixture). Because you are correcting for it when you do a real world tune. Yes, voltage makes a significant difference to lag time/latency - I've attached a comparative table in this link. You might have already seen it.

http://injector-reha...m/shop/lag.html

I have found the idlein an RB25 to work well ovr a significant range ~ 12:1 up to 14:1, the sound changes, the revs and the number of stumbles, etc but anything in that range seems OK. Now obviously this range is an approximate as the absolute values could be wrong since getting the AFR of an idling engine is not accurate with a tailpipe reading.

I have no idea if latency is all that repeatable between injectors operating in a vehicle. But I'd suspect there are significant differences between latency of the individual injectors in stalled in the rail during operation. I say this to imply that there might not massive gains trying to find an optimal latency time, rather just a sweet spot/range.

Edited November 8, 2012 by simpletool

[Lithium]

Trying to work out if everyone in this discussion appreciate the difference between injector timing and injector latency... without being on the same page then I can imagine this could get very confusing for some

[discopotato03]

This is a tread I found with one persons views on this .

http://www.8thcivic.com/forums/hondata/189947-injector-latency-explained.html

If this is the case then I have a better understanding of what this Latency means in relation to compensating pulse widths to allow for the time taken for the injector to react in relation to the electrical signal sent to it . I can see where having the Latency constant wrong may alter pulse widths across the board and change mixtures accordingly .

Anyway from searching in the early hours it seems the std R33 RB25DET 370cc side feed injectors have a Latency or time lag of ~ 0.528 ms where the 740 Nismos I use are 0.66ms so the settings should be 0.132ms .

I can change this easily enough from 0.14 to 0.13 and fiddle my fuel table to suit .

Sorry for my injector timing assumption .

A .

[tranman]

Hi, would someone like to post up their water temp and cranking tables? With the weather becoming increasingly colder, my cold starts are becoming more difficult.

I've played with the settings incrementally until a successful start-up occurs before reverting the values back to what the Tuner had originally set (was tuned in warmer weather).

[zebra]

So....Bumping this back up

What timing advance figures are people seeing/using on their RB25?

Obviously varies dependent on manifolding etc

Just curious as I'm going to buy a few litres of E85 this week and dump it in the 33 while its sitting in my driveway going no where for a few weeks

[Dose Pipe Sutututu]

I posted up a few of my maps on the hypergear thread

[zebra]

cool, I'll have a look