Car stays in low octane map all the time, why?
Thread Starter
On The Tree
Joined: Jul 2003
Posts: 182
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Car stays in low octane map all the time, why? My ls1 engine swapped earlier corvette runs 16-18 total timing all the time. It NEVER goes out of low octane timing map ever,
I still have 20 DTC check engine codes for all the stuff that isnt used anymore on my swap. But what can cause it to stay in this low timing setup?
I still have 20 DTC check engine codes for all the stuff that isnt used anymore on my swap. But what can cause it to stay in this low timing setup?
Re: Car stays in low octane map all the time, why? Probably due to intake air temperature or coolant temperature. There is a table where you can zero out the intake air temp corrections in LS1 Edit. Only way of getting around coolant temps is to run cooler as far as I know.
Re: Car stays in low octane map all the time, why? The direct reason for falling into the low octane
mode is persistent knock detects. These, from
either real (tuning needed) or false (sensors
too sensitive, engine internal or external
mechanical noise) knock.
I would start with reading and checking off the
20 codes and see if any of them pertain to knock
sensors being out. Then, some basic check of
mixture and trims. If these look proper then I'd
try chasing false knock which, given a full
mechanical swap, could come in from hard motor
mounts, exhaust banging, who knows?
mode is persistent knock detects. These, from
either real (tuning needed) or false (sensors
too sensitive, engine internal or external
mechanical noise) knock.
I would start with reading and checking off the
20 codes and see if any of them pertain to knock
sensors being out. Then, some basic check of
mixture and trims. If these look proper then I'd
try chasing false knock which, given a full
mechanical swap, could come in from hard motor
mounts, exhaust banging, who knows?
Re: Car stays in low octane map all the time, why? I would suggest making the 2 tables the same or very close to each other. Have you been Datalogging? have you seen any knock? if so correct where there is pinging and all should be well.
TECH Resident
Joined: Jan 2002
Posts: 754
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From: USA
Re: Car stays in low octane map all the time, why?
I would suggest making the 2 tables the same or very close to each other. Have you been Datalogging? have you seen any knock? if so correct where there is pinging and all should be well.
Making the low octane timing table the same as high octane removes the ability of PCM to pull back timing to stop piston slap and causing long term damage, esp with a SC.
I have seen at least 6 C5s with trashed engines with SC and all had knock turned off
Real knock has to be dealt with and then any false knock be tuned out, not just removing the ablilty for PCM to react to real knock
TECH Addict
Joined: Nov 2001
Posts: 2,551
Likes: 0
From: St Louis, MO
Re: Car stays in low octane map all the time, why? You probably dont have the fuel level sensor hooked up to the pcm since its a retrofit. This might be why the pcm can never reset to the high octane map.
