460cc + SAFCII = PING?!?!

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sil80drifter
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I am using SAFCII, and don't know how this works for you guys, but I have it set for throttle position at 40% (low throttle) and 80% (high throttle), NOT TURBO YET, just installed the injectors.

I got 460cc injectors and at -25% all across the low-throttle settings, my car pings like crazy betewen 1000 and 3000 rpm, when just press the gas and there is a LITTLE load. My high throttle map is set to -30% all across the board, but when I hear the ping under low-throttle and punch it, (throttle position around 80% to 100%+) the ping goes away, as if the mixture richens out enough to not ping. It doesn't make sense to me.

-25% on low throttle + little load between 1000 and 3000rpm = ping-30% on high throttle, same rpm range at WOT = no ping. what is the matter here???

Is there a timing issue here? Do I not understand something about higher flow injectors? Is there something I am doing wrong with SAFC? Input is highly appreciated!

sil80


Prok0
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Why would you go with less fuel on the high throttle map?And -25 with 460 injectors would end up being 345cc...stock injectors are 270cc... so I dont see how your even starting your car... thats a whole crap load of extra fuel...

*edit* I see your a 90 so I assume your SOHC....Im not sure what size injectors sohc's came with stock so if my prior statement makes no sense thats why..

Structure240sx
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the sohc also use 270's they are jsut top feed. and i tol you this in another post you have to set your low throttle map to 0% to trim the injectors correctly. at idle and cruising your ecu thinks you have 270's but theres really 460's in there.

toki
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huh?

"set your low throttle map to 0% to trim the injectors correctly."

could you rephrase that? I'm sorry...but im just about to put 450s in my SOHC too....so I don't want to run into this same problem.

Structure240sx
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your right sorry.

ok so you have the low map at -25% correction lets say and set at 40% throttle. this means that map is kicked in once you hit 40% throttle. so anything less than that and your running the stock fuel map with no correction. so you are dumping in an extra 190cc of fuel before 40%

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sil80drifter
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So you mean that my throttle points should be 0% for low and some other value (like 40%) for high? Not sure your logic is quite right for the SAFC...here is how the SAFC works:

With low throttle point set at 40% and high throttle at 80%, what it means is that BELOW 40%, it considers everything to be low throttle map and it will correct everything accordingly. I.e: I have it set at 40% for LT, and -25% correction at 800rpm (idle). Whem I am idling, the SAFC is corecting the fuel to be -25%, because it knows to do that at 800rpm, no matter what the throtle position is (but it would be 0% since idle only can occur when you let off the pedal).

Again using the point of 40%, if let's say at 3000 rpm LT is set to -25% and HT is set to -30% (these are correction numbers not throttle position numbers now), and I am at 3000rpm, while the car is at less than or equal to 40% throttle, the SAFC will make the correction to be -25%. If the car is at 80% or more throttle, then the correction at that rpm will be -30%. If the car is between 40% and 80% throttle, the SAFC will interpolate the correction values between -25% and -30% depending on throttle position being either closer to 40% or 80%.

IF the LT point is set at 0% and HT at let's say 40%, then the SAFC would always be interpolating between 0% and 40%, or always use the HT map, if the car is over 40% throttle.

prok0 -> The reason one can't just adjust for the % of injectors (i.e.: I can't just go -40% on the 460s across the board just because thats almost 270cc) is because the duty cycle pulse width adn duty cycle are two different things you have to account for when you try to formulate your corrections with the SAFC. Especially at lower RPMS, the larger injectors won't be AS lean as you'd think, just because they are large the pulse width is similar and the injector doesn't really injecto THAT much more fuel into the engine than a stock 270cc. This has been proven by me because I can idle just fine at -10%, but at -30% the car stutters and just doesn't get enough fuel for the incoming air. At higher rpm, the injector duty cycle goes up in a more or less linear fashion, so the correction needs to be made accordingly (from 3000 rpm to 6400rpm I start at -25% and go to -40%).

sil80

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huguetpj
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sil80drifter wrote:So you mean that my throttle points should be 0% for low and some other value (like 40%) for high?


It is my opinion you should not. 40 and 80 seem good numbers to me, I usually use 30-80 when setting SAFCs. Are you sure you are pinging as in detonating? Maybe it is something else. Do you have your timing at stock?

Remember the SAFC changes the MAF voltage the ECU sees. And the ECU uses this MAF voltage to calculate not only injector duty cycle but timing advance/retard as well. So when you mess with this signal you are messing with both of them. When you use a negative setting on the SAFC the ECU thinks there is less load on the motor than there actually is so it could be advancing the timing. Once you reach more than 80% TPS (WOT) the ECU goes into high throttle mode (for lack of a better term) and maybe (don't quite remember) retards timing a bit. So this could explain detonating at low load but no prob at high.

Try moving base timing a bit and see if it does anything.

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WAbernethy
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Mine did the same thing when I first set it up, before going to the dyno. It looks like you have about the same setup as me. I'm using low imp 460cc rx7 injectors and the safc ii. Right now, mine is set to -22 for low throttle and -35 at low rpm to -44 at higher rpm for the high throttle setting. High/Low is 20/50. Try adding a couple % to the low throttle. Of course, the best thing you can do is stick a wideband up your tailpipe. :)

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sil80drifter
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I will dyno the car after I turbo it (and I am turboing it today, which is probably the most awesome event of this summer), so I will definitely tune it more precisely, and for the lack of timing management (going to "DIY chip the ECU" soon, so didn't buy the MSD BTM), I'll retard base timing up to 5-7 degrees, anyway. Hopefully this will solve my issues for now. Thank you for your greatly helpful input guys, I can always use a little push in the right direction.

sil80

Structure240sx
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i stand corrected. just moved up my low throttle positon point and there wasno change on my wideband. thanks for pointing that out to me. maybe i will be able to get a better tune

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huguetpj
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Structure240sx wrote:i stand corrected. just moved up my low throttle positon point and there wasno change on my wideband. thanks for pointing that out to me. maybe i will be able to get a better tune


It ain't that important when tunning WOT, but it sure helps when tunning your idle and cruise economy :pface

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sil80drifter
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I was just going to say that... and that it seems like there is a lot of play involved while tuning for daily driving, compared to the tuning for the big throttle stomp which only requires a tune for one throttle position at the RPM points selected, instead of many points at many rpms, load/no load, etc etc etc.

sil80

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huguetpj
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I really don't think it is that hard. I first start with the car at a stand still. Tune the low throttle map until I see no hesitation when accelerating (at a stand still). Start tuning from 1k rpm up. Then drive around to see if any of the low throttle map needs adjusting for daily driving.

Once the low throttle map is ready I take a some runs on the highway. 4th gear first. Once that is ok 3rd gear, then 2nd. I start on the higher gear to make sure if something is wrong the car suffers less :rolleyes Depending on the car it takes 2 or 3 people to do it... one watching the road, one watching the EGT gauge and me fiddling with the SAFC.

I've gotten very good at this... jeje... just a few tweaks are necessary once we get to the dyno. This makes it much cheaper.

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sil80drifter
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link!!:

http://www.nissaninfiniticlub....43187

sil80

bruinbear714
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sil80drifter wrote:I am using SAFCII, and don't know how this works for you guys, but I have it set for throttle position at 40% (low throttle) and 80% (high throttle), NOT TURBO YET, just installed the injectors.

I got 460cc injectors and at -25% all across the low-throttle settings, my car pings like crazy betewen 1000 and 3000 rpm, when just press the gas and there is a LITTLE load. My high throttle map is set to -30% all across the board, but when I hear the ping under low-throttle and punch it, (throttle position around 80% to 100%+) the ping goes away, as if the mixture richens out enough to not ping. It doesn't make sense to me.

-25% on low throttle + little load between 1000 and 3000rpm = ping-30% on high throttle, same rpm range at WOT = no ping. what is the matter here???

Is there a timing issue here? Do I not understand something about higher flow injectors? Is there something I am doing wrong with SAFC? Input is highly appreciated!

sil80


This has nothing to do with your throttle settings, well, indirectly. It has more to do with the nature of piggyback systems.

In order to allow your car to run larger injectors, the piggyback ALTERS the MAF signal, which tricks the ecu into thinking less air is flowing, and thus, opens the injectors for a shorter amount of time. However, the side effects of this is timing gets screwed up because now the ecu is looking up the wrong entry on its timing map because of the modified MAF signal.

I've also had this problem with the emanage but fortunately I have an ignition map that I can play around with to semi-fix that problem.

This is why HACKED MAF, piggybacks, dual MAFs, Z32 mafs etc etc don't work unless the system can also account for the timing changes.

Try backing down your base timing by a few degrees. I wouldn't be surprised if it takes more than 5 degrees to stop the pinging. But your performance will suffer across the board.

Do you have EGR?

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sil80drifter
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I understand... how come the pinging doesn't disppear by using higher octane gas? I used 87 before I turboed my car last week, now I use 91, but it's still there at same RPMs qnd no boost, so I guess I'll retard the timing up to 5 degrees. I'll be chipping the ECU soon, so I'll be able to adjust the timing as needed, not just retarding it across the board. I just got rid of my EGR, it was a PIA but I did it :) The pinging was there before and after removal (and by that I mean, I got rid of it by richening out the mix, then leaned it out after EGR removal, it came back, so I richened it out again). I am running -12% from 1000-2800rpm now. Too rich but oh well...

sil80


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