Getting some kind of hard cut on the track?

[dave-]

Running a custom E85 tune which I experience some kind of hard cut over 6000 rpm in 4th or 5th gears. It feels like I've hit the limiter but obviously I'm no where near that RPM. It isn't consistent in that yesterday at the track I could do a 10min session and not have it once, then go out an hour later and have it occur every single lap. Haven't experienced it on the street but I had the same scenario occur when I tried the OFT E85 tune last year at the same track.

Have uploaded 2 logs, log0076_extract.csv definitely had it happen at the end.
http://www.datazap.me/u/dave/e85?log=1&data=15

Stock tune doesn't do it so I'm convinced it is something related to the tune. Had my tuner there so tried increasing the Engine Load or MAF Limit's but didn't help and not game to play with anything else while not on the dyno. His normal platform is tuning Evo's so has asked me to investigate here in the hope we can find the issue quicker.

Couple of variables, car is stock bar overpipe back invidia exhaust. Weather isn't a factor as it did it when ambient ranged from 25-35 deg C. Fuel level is irrelevant as it occurred with a near full tank.

[steve99]

Originally Posted by dave-

Running a custom E85 tune which I experience some kind of hard cut over 6000 rpm in 4th or 5th gears. It feels like I've hit the limiter but obviously I'm no where near that RPM. It isn't consistent in that yesterday at the track I could do a 10min session and not have it once, then go out an hour later and have it occur every single lap. Haven't experienced it on the street but I had the same scenario occur when I tried the OFT E85 tune last year at the same track.

Have uploaded 2 logs, log0076_extract.csv definitely had it happen at the end.
http://www.datazap.me/u/dave/e85?log=1&data=15

Stock tune doesn't do it so I'm convinced it is something related to the tune. Had my tuner there so tried increasing the Engine Load or MAF Limit's but didn't help and not game to play with anything else while not on the dyno. His normal platform is tuning Evo's so has asked me to investigate here in the hope we can find the issue quicker.

Couple of variables, car is stock bar overpipe back invidia exhaust. Weather isn't a factor as it did it when ambient ranged from 25-35 deg C. Fuel level is irrelevant as it occurred with a near full tank.

assume your talking about at time 2975 seconds ?

can see throttle close with rpm arround 6000 not sure if that is you or not.
you speed is in excess of 140 kmh its my understanding from other track guys that even if traction vsc is OFF , at speeds in excess of 140 kmh it will kick back in trying to save you if it detects vehicle traction loss or slide. you have to do pedal dance to disable completly.

maybe does not do it on stock tune due less power at 6000 rpm than tuned on e85 so does not try to break traction

note your iam is 0.78 which indicates your getting significant knock somewhere. dont think that is problem though. but wrth looking at

arround 5000 rpm at load .7 your pulling 3 and 4 degrees flkc with iam at 0.7
your ltft is between 6 and 9% so unless you e85 mix is off i would be pointing that out to tuner
your afr and commanded afr are also significantly different at wot may be 02 scalng limit but again worth checking

[Tye300]

Last time I tracked I experienced a lap when I could not rev past 6000rpm. The car only did that on one lap and I checked the temps, the oil was 115degC and the water was almost at 120degC. It was my second to the last lap of the day, and I just went straight to my cool down lap. Driving the car home, I could rev it past 6000rpm again. Maybe another safety net with high temps I suppose? I'm installing a tranny oil temp guage, maybe it has something to do with that. I was using e85 that day.

[dave-]

The track is Phillip Island ([ame="http://en.wikipedia.org/wiki/Phillip_Island_Grand_Prix_Circuit"]Phillip Island Grand Prix Circuit - Wikipedia, the free encyclopedia[/ame]).

I should have added that I am doing the pedal dance as the speed on semi's through the big sweepers had the V-LSD feature kick in even with TC/DSC off and was very unsettling. While log0076_extract.csv is going around turn 12, previous experience has had it happen after the car was already on the straight after that turn. Steering inputs or lack of traction are not factors here.

I can't comment on the IAM or knock values you mention. Car was tuned on the dyno using United E85 and was running the same fuel at the track.

Also not heat related. I have a setrab 19 row oil cooler which keeps temps under 110degC even on a 35degC day and 20 min sessions. Water temp would not have gone higher than 105degC.

My tuner suspected some sort of MAF or Load limit being reached so was hoping one of the tuners here could comment.

I'll check my gopro footage later and upload to YouTube if there is anything which shows it.

[dave-]

Any experienced ROM editors/tuners care to comment? @Kodename47 @mad_sb @Shiv@Openflash @DeliciousTuning @Td-d @moto-mike

We can't replicate it on the dyno and I'm not in favour of testing tweaks on the fly at the track, not at least without a wideband hooked up. Though I might have one mounted in the stock header and wire it up for that purpose if need be.

I'm not against paying for another tune or the time for a pro's experience but we're thinking it is something simple and others more familiar with the platform might have seen before?

I'm actually surprised no one has experienced it with the OFT E85 tune as I tried that with no alterations and had the problem.

[Td-d]

My first call would be one of the load limiter tables, since the most obvious impact of E85 would be a significantly higher potential engine load. The stock tables (b, and c) cap out at 1.3 - but, this is generally a problem at lower RPMs (and you are achieving loads up to 1.35). Second call would be the MAF limiter, 200 g/s stock - but you're not hitting over 176 g/s.

[steve99]

You open loop maf scaling seem quite a bit off your sensor is pegged rich limit of scale 11.3 (it may be running richer) where your commanded afr is 12 from about 5000 to redline, about 8% or more error.

If you correct the maf scaling it will also reduce the load calculation by similar amounts the ecu does which will likely reduce your load values to below the max limits.

[dave-]

Originally Posted by Td-d

My first call would be one of the load limiter tables, since the most obvious impact of E85 would be a significantly higher potential engine load. The stock tables (b, and c) cap out at 1.3 - but, this is generally a problem at lower RPMs (and you are achieving loads up to 1.35). Second call would be the MAF limiter, 200 g/s stock - but you're not hitting over 176 g/s.

That was the initial thought also. Defs for ZA1JA01G don't have an Engine Load Limit C? Only A & B that I can see.

Originally Posted by steve99

If you correct the maf scaling it will also reduce the load calculation by similar amounts the ecu does which will likely reduce your load values to below the max limits.

Need to switch back to stock 98 before I play around there. But the scale being used is from OFT Stg2 EL A01G v2.061. Also regarding your earlier comment about IAM being low, my tune has all the stock knock correction tables so it starts at 0.7

[steve99]

Originally Posted by dave-

That was the initial thought also. Defs for ZA1JA01G don't have an Engine Load Limit C? Only A & B that I can see.



Need to switch back to stock 98 before I play around there. But the scale being used is from OFT Stg2 EL A01G v2.061. Also regarding your earlier comment about IAM being low, my tune has all the stock knock correction tables so it starts at 0.7

You can do maf scaling on E85 as long as you have a consistent mix. If you only use united E85 its guaranteed 85% and consistent so you can scale maf on it. I have done that and it works great. my load is now below 1.30.

Yes I assumed your tuner had set IAM initial to 1 (most tuners do this) but I was wrong. however their is still knock evident even with IAM at 0.7 your also getting knock on each shift over 5000 is your tuned rom based on an A01G ?? if its an earlier rom ie A00G 900G 700G then their was an error in the setting of the Transient Ignition Retard table and TIR was disabled above 5000 in the A01G and later roms it was fixed and disable set to above 10000 ie its always active. The Transient retard not being active was believed to be a contributing factor to di seal failure due knock with guys who drove cars hard especially on track.

http://www.datazap.me/u/dave/e85?log...zoom=5914-6456

[Xero-Limit]

I didn't read the whole thread but you shouldn't use MAF scaling to do e85 fueling. Otherwise you will exceed the load limits and need to adjust accordingly. None of our customers have this issue but we use EcuTek and directly adjust fuel vs trying to band aid it with MAF scaling.

[dave-]

Originally Posted by steve99

Transient Ignition Retard

All the transient ignition tables are unchanged from the stock A01G map I pulled from my car so that isn't an issue.

Originally Posted by moto-mike

I didn't read the whole thread but you shouldn't use MAF scaling to do e85 fueling. Otherwise you will exceed the load limits and need to adjust accordingly. None of our customers have this issue but we use EcuTek and directly adjust fuel vs trying to band aid it with MAF scaling.

My tuner also advised against playing with MAF scale. The trims weren't so bad when we first tuned it so I'll keep logging and if the trims remain excessively high we'll chuck it back on the dyno for some fine tuning.

[s2d4]

Originally Posted by moto-mike

I didn't read the whole thread but you shouldn't use MAF scaling to do e85 fueling. Otherwise you will exceed the load limits and need to adjust accordingly. None of our customers have this issue but we use EcuTek and directly adjust fuel vs trying to band aid it with MAF scaling.

Why not if E85 is actually consistent? All year long and only ever use E85?

Can you explain how MAF scaling would be a bandaid?

[steve99]

Originally Posted by dave-

All the transient ignition tables are unchanged from the stock A01G map I pulled from my car so that isn't an issue.



My tuner also advised against playing with MAF scale. The trims weren't so bad when we first tuned it so I'll keep logging and if the trims remain excessively high we'll chuck it back on the dyno for some fine tuning.

dave look at the logs it pulling 4 degrees flkc all the time , maybe its not TIR related but its pretty bad knock, even if your iam is initially set to 0.7 the ecu will try to increase the iam and hence the timing. Your pulling -4 degrees with an iam of 0.7 after considerable run time on E85 their is something wrong with the tune. You can see the positive flkc where the ecu is trying to add timing then it pulls 3 or 4 degrees negitive consistently thats what is keeping you iam less than 1.

[Xero-Limit]

Originally Posted by s2d4

Why not if E85 is actually consistent? All year long and only ever use E85?

Can you explain how MAF scaling would be a bandaid?

When you alter MAF you alter load. Load is used extensively in modern ECUs and it affects every bit of operation from where it applies knock correction, startup fueling, timing maps, and everything else in between. When you mess with MAF scaling to correct a fueling issue, you're altering all of that. By a whopping 40% when you factor in e85. It's a technique of last resort (i.e. when you can't directly alter injection values) but a much more effective method is to alter injector scaling or fuel constant (i.e. nissan).

In this case it looks like MAF may have been used but load limits are still capped.