Low octane map for bad gas?
Thread Starter
Staging Lane
Joined: Dec 2002
Posts: 57
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From: Dallas Tx
Low octane map for bad gas? For some crazy reason, cant figure out why, my car is using the low octane fuel and spark map even thoough I have 96 octane gas is it. The low octain map pulls timing down to 23 advance spark while the high oct. map is set at 29 at wot. Any of you guys heard of this? Any help would be welcome!
TECH Fanatic
Joined: Nov 2001
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From: Las Cruces, NM
Re: Low octane map for bad gas? If you get some knock retard the computer will drop to the low octance table. It assumes you got bad gas. Once you put a little gas in it figures you got better gas and switches over to the high octane table.
Gary
Gary
Teching In
Joined: Jan 2003
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From: Midwest City, OK
Re: Low octane map for bad gas? You should not have to reset your PCM to get your LTFTs to adjust to the high octane tables. It takes about 50 or so miles of driving to get everything to stablize and maybe you haven't driven far enough.
After reading other posts, I found some good info. Check your fuel tank level. Apparently, you need to have a 20% increase seen in the fuel level to reset to the high octane tables.
<small>[ April 16, 2003, 01:16 PM: Message edited by: 98M427 ]</small>
After reading other posts, I found some good info. Check your fuel tank level. Apparently, you need to have a 20% increase seen in the fuel level to reset to the high octane tables.
<small>[ April 16, 2003, 01:16 PM: Message edited by: 98M427 ]</small>
TECH Resident
Joined: Jan 2002
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From: USA
Re: Low octane map for bad gas? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Tin Indian:
<strong> Can LS1Edit be used in order to keep the PCM from ever using the low octane tables? (no matter if it sees knock retard or not)
Ron, </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">No the bit that is set for bad gas is done within the operating software of the PCM and not within the calibration tables.
Most people will either solve the knock issue, tune knock circuit or raise the timing in low octane table.
The PCM must see at least a 20% increase in fuel tank from last time key was turned off to being turned on to reset bad gas bit.
<strong> Can LS1Edit be used in order to keep the PCM from ever using the low octane tables? (no matter if it sees knock retard or not)
Ron, </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">No the bit that is set for bad gas is done within the operating software of the PCM and not within the calibration tables.
Most people will either solve the knock issue, tune knock circuit or raise the timing in low octane table.
The PCM must see at least a 20% increase in fuel tank from last time key was turned off to being turned on to reset bad gas bit.
