liquid_helix136

So I had tuned my 2007 SOS supercharged s2k myself on flashpro, while running just ID1k injectors and an Aeromotive 340lph pump, I was able to get the car running safely and perfectly. Only problem was, the Injector Duty Cycle was about 95%. I dont like my stuff running at the ragged edge, so I installed the Radium FST-R with a Walbro 255 inside it. I adjusted the fuel pressure to about stock levels and tuned the car again today. Everything is perfect, I got the fueling looking great. Except when I did full throttle pulls, I was able to get the car running 12.0-12.5 all the way up to about 7800 rpms, and then it goes lean, like fuel starvation up to redline, sometimes it only goes as lean as 13.1 and sometimes it goes to 13.7.

I checked my duty cycle and its about 75%, so I upped the fuel pressure even more and tried again, same result, except now everywhere else was running richer, (between 11.6-12.2). I checked the datalogs and it appears that the ignition timing is taking a dump at the same time the fuel is leaning out. The really weird part is I checked my ignition retard, and its reading 0-<1* of retard. However the timing is going from 16-17* to sometimes 9*, sometimes 7*, and at one point it tanked all the way to 0* timing!

I took a datalog, and these don't show the ignition dump as bad, but it's still there, and the lean out is still there.

Does anyone know whats going on here?

Click link to access tune and datalog!
https://drive.google.com/drive/u/0/f...XEtSEl5WF95S2M

Here's at least a screenshot of the datalog
[attachment=90994:Leanout1.png]

killerbee_vr6

Looks like you're out of fuel. You on the stock returnless system? My logs looked just like that.

liquid_helix136

Whats funny is when I was on the stock returnless system, I had enough fuel for this set up, the injector duty cycle just happened to be at 95-100% dependent on the weather.

I got a fuel surge tank with an adjustable fuel pressure regulator to accommodate that, Duty % is in the 70s now, so I *SHOULD* have more headroom.

I increased the pressure on the tank to see if that would help, and it did nothing. I think the fuel system is delivering the fuel, but the timing is tanking, causing a lot of the fuel to be unburnt, resulting in the lean AFRs. (As I understand it, o2 sensors read burnt fuel only)

soulicious

I wouldn't mess around with the fuel pressure after getting tuned on a specific base pressure. Maybe your belt is not slipping as much up top so you get leaner AFRs. The relevant parts of your ignition map might need to be checked if that's the case.

liquid_helix136

I'm tuning it myself. I've built this entire map from scratch. I've gotten professional tunes and they're always so underwhelming.

If you look at the tune, I've massively increased the fuel up top trying to fix the lean spot but that's why I'm posting. If it was just running lean, I would just increase the fuel in that spot. But I've done so, and there are zero changes. So I ruled out fuel starvation by increasing the fuel pressure and increasing the fuel values, but the lean spot stayed the same.

My main concern is why ignition is dropping so much in that area without the ecu showing any ignition retard?

The ignition map reads 15* in that spot, ignition retard on datalog shows 0* retard yet actual timing on datalog is between 0* and 9* dependent on the run.

soulicious

I'm not familiar with flashpro, but is it retarding the timing based on your AIT? Maybe there's a table for that.

soulicious

I just reread your last sentence. I'm not sure why the data log says that. There's probably a surrounding cell or cells that needs adjustment.

soulicious

Post your ignition table. There's no folder found in your google link...I'm on my phone

s2000Junky

If you upped the pressure and it only richened up bellow the problem lean area, then that tells me your pump is too small. Why you went from a 340 to a 255 is beyond me. Instead of messing with the fuel pressure, have you tried returning it to where it was and just upping the appropriate duty cycle on the injectors instead? 75% shouldn't be your cap, at 13 -13.7 you should be able to add 5-10% more duty at that point and easily knock your afr down to optimum levels. I would have no problem running 85-90% duty, it should leave you plenty to account for seasonal changes/environment.

A lack of timing will result in a 'richer' condition normally, If the engine is still pulling clean without detonating. But I think you might have something else influencing knock or false knock right there, so you are not getting a "clean" combustion at that point possibly. I recall you having a related issue with your tuner not being able to advance timing beyond what would seem a typical point, because you were getting knock or false knock. So right now it appears to me you may have two separate issues, influencing each other but are not related. Your lack of fuel and your timing.

Your fuel if too lean can cause pre ignition, and that would pull timing as a symptom if your ecu has the provisions set up for that. But don't confuse lack of timing for your lean condition, because it doesn't work that way.

I would first address your fuel pressure and duty cycle, make sure those are properly calibrated with a bigger pump if needed, and more duty cycle first and foremost so your getting the proper afr to redline.

DaGou

Good point Junky, it went right by me that he went down to a 255. We have similar set ups and I do not have the issue and the only equipment difference is I run two 340s(one AEM and one Aeromotive).

Get yourself an Aeromotive Stealth 340 and it will be quieter than the Walboro as well.

I am more of a wrench turner than an engine tuner but I was under the impression that duty cycle is a resultant of your fuel demand. Are you saying you can cap your duty cycle? If so I would certainly lift that cap to help diagnose your problem. However I do not like running (more accurately having a control point) of 90% for any type of control valve, an injector is a type of control valve. Different people say different max numbers for duty cycle, and lots say 90% Generally you can say the closer you get to 100% duty cycle the more you lose control. My magic number is 85% tops, I sleep better at 80%.

Anyway what does it say if his duty cycle is not capped and it 75% because that is all it needs to be? I guess it says his injectors are big enough, and that his fuel pump is to, and he has enough pressure. If it was fuel starvation I would expect the injectors to be doing all they could and be open all the way.

You and Junky forgot more about tuning than I know so I should shut up and let you all figure it out. But since I pushed Liquid in the direction of a FST-R I feel obligated to throw in my 2 cents even if it is only worth a penny!