high low octane tables
high low octane tables What causes the pcm to revert to the lower octane table?
Obviously if you run lower octane it should revert to the low table but how does the vehicle tell what octane you are running
What conditions are a deciding factor when it comes to choosing high/low tables?
Obviously if you run lower octane it should revert to the low table but how does the vehicle tell what octane you are running
What conditions are a deciding factor when it comes to choosing high/low tables?
TECH Senior Member
Joined: Nov 2001
Posts: 7,036
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From: Lake Zurich, IL
Several things determine... the octane of the gas you use doesn't matter unless you get knock
more knock = closer to low octane, less knock = closer to high octane... it's not a yes/no , use high or use low... it's a blending of both
having a knock sensor code, failed MAF, probably failed MAP and O2 sensors as well (basically if any of the primary sensors fail, it'll go into a limp mode and use the low octane table excuslively)
more knock = closer to low octane, less knock = closer to high octane... it's not a yes/no , use high or use low... it's a blending of both
having a knock sensor code, failed MAF, probably failed MAP and O2 sensors as well (basically if any of the primary sensors fail, it'll go into a limp mode and use the low octane table excuslively)
TECH Addict
Joined: Jul 2002
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Originally Posted by horist
Several things determine... the octane of the gas you use doesn't matter unless you get knock
more knock = closer to low octane, less knock = closer to high octane... it's not a yes/no , use high or use low... it's a blending of both
having a knock sensor code, failed MAF, probably failed MAP and O2 sensors as well (basically if any of the primary sensors fail, it'll go into a limp mode and use the low octane table excuslively)
more knock = closer to low octane, less knock = closer to high octane... it's not a yes/no , use high or use low... it's a blending of both
having a knock sensor code, failed MAF, probably failed MAP and O2 sensors as well (basically if any of the primary sensors fail, it'll go into a limp mode and use the low octane table excuslively)
. No need to -> ttttttttttttttttt.
Correct. If the knock sensors are reporting a lot of knock, it drifts down to the low octane table. If the knock sensors are reporting no knock, it drifts up to the high octane table. It just depends how much knock the sensors are reporting to the pcm.
If its a blend like your saying, what would make it only read the low octane table?
i have some WOT runs on A-tap that i did yesterday and my timing is 19 thru the whole run, which is what the low octane table is set at.
I did about 4 runs, the first 3 i got KR right when i stabbed it. the last run i didnt get any KR.
If its only reading of the low octane table, do i have a serious problem?
i have some WOT runs on A-tap that i did yesterday and my timing is 19 thru the whole run, which is what the low octane table is set at.
I did about 4 runs, the first 3 i got KR right when i stabbed it. the last run i didnt get any KR.
If its only reading of the low octane table, do i have a serious problem?
Yep it could be a number of things to send you into Low Octane table.Such as False Knock ,Just exaust banging the Floor board sent me into low Octane mode.
Last edited by Pro Mouse; Jul 24, 2005 at 12:51 PM.
