Info on "Low Octane Table"
09-08-2017, 09:06 AM
#1
Drifting
Thread Starter
Info on "Low Octane Table"
See signature for details on my C5. A few weeks ago my car started running very poorly at the track. It was a stinking hot FL day but it was running much worse than ever before under similar conditions.
Took it to my tuner who put it on the dyno and could find no mechanical problems...no misfire, making normal boost, etc. but he did note the AFR was on the lean side. I have run this car for many years with the original tune from Lingenfelter without issues. He saw some detonation and the ECM pulling timing. He did richen the AFR.
He went on to tell me he determined the ECM had seen so much detonation that it had switched over to the "Low Octane Table" with even less timing. He instructed me to put in some 100 octane race gas and that it would take some time for the car to "relearn" and switch back to the normal table. He said he could not reset the table manually. I was always of the belief my setup was OK on 93 octane pump gas even in the FL heat. My tuner told me it was possible I had gotten some bad gas that was not really 93 octane.
While relieved there was no major problem with my car, I am a bit puzzled by all this information. My tuner has a stellar reputation and has done great work on my C5 and C6 and I trust him completely but I would appreciate any insight on the situation from the Forum gurus.
__________________
BIGMAC
'98 Torch Red A4 Coupe
Lingenfelter Magnuson 112 S/C Package
Lingenfelter GT2-3 Cam and Springs
Breathless Performance LT Headers, Bassani X-Pipe, Borla Stingers, DMH Electric Cutouts
Yank TC 3200 Stall, Rossler Transmission
RPM 3.73 Differential, LPE HD Output Shafts
436 RWHP, 404 RWTQ, Best 1/4: 11.58 @ 121
Took it to my tuner who put it on the dyno and could find no mechanical problems...no misfire, making normal boost, etc. but he did note the AFR was on the lean side. I have run this car for many years with the original tune from Lingenfelter without issues. He saw some detonation and the ECM pulling timing. He did richen the AFR.
He went on to tell me he determined the ECM had seen so much detonation that it had switched over to the "Low Octane Table" with even less timing. He instructed me to put in some 100 octane race gas and that it would take some time for the car to "relearn" and switch back to the normal table. He said he could not reset the table manually. I was always of the belief my setup was OK on 93 octane pump gas even in the FL heat. My tuner told me it was possible I had gotten some bad gas that was not really 93 octane.
While relieved there was no major problem with my car, I am a bit puzzled by all this information. My tuner has a stellar reputation and has done great work on my C5 and C6 and I trust him completely but I would appreciate any insight on the situation from the Forum gurus.
__________________
BIGMAC
'98 Torch Red A4 Coupe
Lingenfelter Magnuson 112 S/C Package
Lingenfelter GT2-3 Cam and Springs
Breathless Performance LT Headers, Bassani X-Pipe, Borla Stingers, DMH Electric Cutouts
Yank TC 3200 Stall, Rossler Transmission
RPM 3.73 Differential, LPE HD Output Shafts
436 RWHP, 404 RWTQ, Best 1/4: 11.58 @ 121
09-08-2017, 01:25 PM
#2
Burning Brakes
Sounds like the knock learn factor was effected which blends the low and high octane maps... 0 = 100% low map and 1.00 = 100% high map. I got stuck at 0.45 once after tuning SD... it took months to recover. Prob cause its mainly a track car and didn't see appropriate conditions. I just matched low to high maps, but I was NOT getting any detonation.
You need to find out why your KLF decreased and make sure there's no knock (or false knock). I think your tuner should have run the high map on the dyno before adjusting AFR, as timing effects it. If everything checks out ECU needs to relearn or you can match tables in the mean time... learning is better and safer though, but can take awhile.
You need to find out why your KLF decreased and make sure there's no knock (or false knock). I think your tuner should have run the high map on the dyno before adjusting AFR, as timing effects it. If everything checks out ECU needs to relearn or you can match tables in the mean time... learning is better and safer though, but can take awhile.
09-08-2017, 01:51 PM
#3
Drifting
Thread Starter
Sounds like the knock learn factor was effected which blends the low and high octane maps... 0 = 100% low map and 1.00 = 100% high map. I got stuck at 0.45 once after tuning SD... it took months to recover. Prob cause its mainly a track car and didn't see appropriate conditions. I just matched low to high maps, but I was NOT getting any detonation.
You need to find out why your KLF decreased and make sure there's no knock (or false knock). I think your tuner should have run the high map on the dyno before adjusting AFR, as timing effects it. If everything checks out ECU needs to relearn or you can match tables in the mean time... learning is better and safer though, but can take awhile.
You need to find out why your KLF decreased and make sure there's no knock (or false knock). I think your tuner should have run the high map on the dyno before adjusting AFR, as timing effects it. If everything checks out ECU needs to relearn or you can match tables in the mean time... learning is better and safer though, but can take awhile.
BIGMAC
09-08-2017, 02:26 PM
#4
Burning Brakes
It should learn at WOT, but like I said took mine a long time. Went from 0 to 0.45 quickly, but took forever to get back to 1.00. Mines for HPDE and I do drive it on the street sometimes... took about 3mo.
09-23-2017, 08:42 AM
#6
Drifting
Thread Starter
09-23-2017, 09:00 AM
#7
Drifting
How would I know what blend of the maps its running?
I get some knock retard (I believe is false) when on the track (HPDE) but haven't wanted to tweak the tune (SD). While the car feels the same, it doesn't seem to break the tires loose like it used to.
Thanks
I get some knock retard (I believe is false) when on the track (HPDE) but haven't wanted to tweak the tune (SD). While the car feels the same, it doesn't seem to break the tires loose like it used to.
Thanks
02-04-2018, 08:01 AM
#8
Drifting
Thread Starter
I know the following is an old thread but I took the car to the season opener at Orlando Speed World and the car is still running like crap. I guess the car is a "slow learner" when it comes to going back to the high octane map. Is there any way to "force" the car to use the high octane map or to "speed up" the learning process? It seems the only fix is to copy the high octane settings to the low octane map so the PCM does not know the difference but this removes the safety margin designed in the system.
BIGMAC
BIGMAC
See signature for details on my C5. A few weeks ago my car started running very poorly at the track. It was a stinking hot FL day but it was running much worse than ever before under similar conditions.
Took it to my tuner who put it on the dyno and could find no mechanical problems...no misfire, making normal boost, etc. but he did note the AFR was on the lean side. I have run this car for many years with the original tune from Lingenfelter without issues. He saw some detonation and the ECM pulling timing. He did richen the AFR.
He went on to tell me he determined the ECM had seen so much detonation that it had switched over to the "Low Octane Table" with even less timing. He instructed me to put in some 100 octane race gas and that it would take some time for the car to "relearn" and switch back to the normal table. He said he could not reset the table manually. I was always of the belief my setup was OK on 93 octane pump gas even in the FL heat. My tuner told me it was possible I had gotten some bad gas that was not really 93 octane.
While relieved there was no major problem with my car, I am a bit puzzled by all this information. My tuner has a stellar reputation and has done great work on my C5 and C6 and I trust him completely but I would appreciate any insight on the situation from the Forum gurus.
__________________
BIGMAC
'98 Torch Red A4 Coupe
Lingenfelter Magnuson 112 S/C Package
Lingenfelter GT2-3 Cam and Springs
Breathless Performance LT Headers, Bassani X-Pipe, Borla Stingers, DMH Electric Cutouts
Yank TC 3200 Stall, Rossler Transmission
RPM 3.73 Differential, LPE HD Output Shafts
436 RWHP, 404 RWTQ, Best 1/4: 11.58 @ 121
Took it to my tuner who put it on the dyno and could find no mechanical problems...no misfire, making normal boost, etc. but he did note the AFR was on the lean side. I have run this car for many years with the original tune from Lingenfelter without issues. He saw some detonation and the ECM pulling timing. He did richen the AFR.
He went on to tell me he determined the ECM had seen so much detonation that it had switched over to the "Low Octane Table" with even less timing. He instructed me to put in some 100 octane race gas and that it would take some time for the car to "relearn" and switch back to the normal table. He said he could not reset the table manually. I was always of the belief my setup was OK on 93 octane pump gas even in the FL heat. My tuner told me it was possible I had gotten some bad gas that was not really 93 octane.
While relieved there was no major problem with my car, I am a bit puzzled by all this information. My tuner has a stellar reputation and has done great work on my C5 and C6 and I trust him completely but I would appreciate any insight on the situation from the Forum gurus.
__________________
BIGMAC
'98 Torch Red A4 Coupe
Lingenfelter Magnuson 112 S/C Package
Lingenfelter GT2-3 Cam and Springs
Breathless Performance LT Headers, Bassani X-Pipe, Borla Stingers, DMH Electric Cutouts
Yank TC 3200 Stall, Rossler Transmission
RPM 3.73 Differential, LPE HD Output Shafts
436 RWHP, 404 RWTQ, Best 1/4: 11.58 @ 121
02-04-2018, 01:07 PM
#9
Burning Brakes
To my knowledge, no. I did some SD tuning recently after cam install and AGAIN I’m stuck at 0 KLF putting me in the low. So I keep my tables matched. It’ll come back, but takes forever... prob since it’s not my DD.
I think ok to match tables, especially if you bumped up KR decay. Such a bad tank resulting in low KLF is prob very noticeable, so you wouldn’t go WOT.
I’m very curious what the tuners do after mapping SD for a customer. Maybe there is a trick. But if customer is stuck at low map for awhile, they would not be happy.
I think ok to match tables, especially if you bumped up KR decay. Such a bad tank resulting in low KLF is prob very noticeable, so you wouldn’t go WOT.
I’m very curious what the tuners do after mapping SD for a customer. Maybe there is a trick. But if customer is stuck at low map for awhile, they would not be happy.