Alternator "fuel economy mode"
09-22-2010, 10:09 PM
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Alternator "fuel economy mode" I know this is mostly a car forum but thought you guys might be able to help me out.
I have been doing some research on why my charge gauge fluctuates so much, and how my truck acts when it is on the high side (@ 15) and low side (@ 12-13). Found out that my year model is equipped with an alternator regulator that has a "fuel economy mode".
My truck seems to run A LOT better when it is on the high side, and seems to be a little sluggish on the low side. Could this be from that regulator or do I need to look else where? Is there anyway to eliminate this "fuel economy mode" to start a process of elimination?
I have been doing some research on why my charge gauge fluctuates so much, and how my truck acts when it is on the high side (@ 15) and low side (@ 12-13). Found out that my year model is equipped with an alternator regulator that has a "fuel economy mode".
My truck seems to run A LOT better when it is on the high side, and seems to be a little sluggish on the low side. Could this be from that regulator or do I need to look else where? Is there anyway to eliminate this "fuel economy mode" to start a process of elimination?
09-24-2010, 10:08 PM
#2
i looked up on google quick about alternator fuel economy mode, i figured it was an internet myth but it looks legit. sorry but i don't know anything about that, but i can tell you any engine would run worse when having lower system voltage (around 12) versus 14-14.5 volts. That's because the ignition system specifically the coils work best with higher, or the highest, voltage. you will get stronger spark to the plugs. It would be analogous to an hei electronic ignition versus an old points ignition where the coil only gets 9 volts.
It would be the voltage regulator on the alternator and they are microprocessors now that are wired to the pcm. Typically, at least what i know on my 2002 camaro, is the pcm sends a 5v turn on signal to the voltage reg. to let the alternator charge, and then it's the circuitry in the voltage regulator that maintains a 13-14.5 system voltage under all conditions. In your case the pcm probably sends various signals to tell the voltage regulator which mode to operate in, info like that would hopefully be found in the service manual available from the dealer. there is almost always a way to make an alternator go full field, which makes it output the most voltage it can for a given rpm so you would see maybe 14-15 volt at idle to 2000 rpm but if you rev it higher would see higher voltage. this is only for testing purposes obviously. you may be able to jump the voltage reg. to make it work in traditional mode all the time, otherwise maybe look into a replacement voltage regulator if you can find them that do away with that fuel economy crap, or a alternator out of a different vehicle that fits that doesn't have that reg. but you would probably then have to worry about the pcm throwing codes. hope that helps.
It would be the voltage regulator on the alternator and they are microprocessors now that are wired to the pcm. Typically, at least what i know on my 2002 camaro, is the pcm sends a 5v turn on signal to the voltage reg. to let the alternator charge, and then it's the circuitry in the voltage regulator that maintains a 13-14.5 system voltage under all conditions. In your case the pcm probably sends various signals to tell the voltage regulator which mode to operate in, info like that would hopefully be found in the service manual available from the dealer. there is almost always a way to make an alternator go full field, which makes it output the most voltage it can for a given rpm so you would see maybe 14-15 volt at idle to 2000 rpm but if you rev it higher would see higher voltage. this is only for testing purposes obviously. you may be able to jump the voltage reg. to make it work in traditional mode all the time, otherwise maybe look into a replacement voltage regulator if you can find them that do away with that fuel economy crap, or a alternator out of a different vehicle that fits that doesn't have that reg. but you would probably then have to worry about the pcm throwing codes. hope that helps.
09-27-2010, 10:36 AM
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i looked up on google quick about alternator fuel economy mode, i figured it was an internet myth but it looks legit. sorry but i don't know anything about that, but i can tell you any engine would run worse when having lower system voltage (around 12) versus 14-14.5 volts. That's because the ignition system specifically the coils work best with higher, or the highest, voltage. you will get stronger spark to the plugs. It would be analogous to an hei electronic ignition versus an old points ignition where the coil only gets 9 volts.
It would be the voltage regulator on the alternator and they are microprocessors now that are wired to the pcm. Typically, at least what i know on my 2002 camaro, is the pcm sends a 5v turn on signal to the voltage reg. to let the alternator charge, and then it's the circuitry in the voltage regulator that maintains a 13-14.5 system voltage under all conditions. In your case the pcm probably sends various signals to tell the voltage regulator which mode to operate in, info like that would hopefully be found in the service manual available from the dealer. there is almost always a way to make an alternator go full field, which makes it output the most voltage it can for a given rpm so you would see maybe 14-15 volt at idle to 2000 rpm but if you rev it higher would see higher voltage. this is only for testing purposes obviously. you may be able to jump the voltage reg. to make it work in traditional mode all the time, otherwise maybe look into a replacement voltage regulator if you can find them that do away with that fuel economy crap, or a alternator out of a different vehicle that fits that doesn't have that reg. but you would probably then have to worry about the pcm throwing codes. hope that helps.
It would be the voltage regulator on the alternator and they are microprocessors now that are wired to the pcm. Typically, at least what i know on my 2002 camaro, is the pcm sends a 5v turn on signal to the voltage reg. to let the alternator charge, and then it's the circuitry in the voltage regulator that maintains a 13-14.5 system voltage under all conditions. In your case the pcm probably sends various signals to tell the voltage regulator which mode to operate in, info like that would hopefully be found in the service manual available from the dealer. there is almost always a way to make an alternator go full field, which makes it output the most voltage it can for a given rpm so you would see maybe 14-15 volt at idle to 2000 rpm but if you rev it higher would see higher voltage. this is only for testing purposes obviously. you may be able to jump the voltage reg. to make it work in traditional mode all the time, otherwise maybe look into a replacement voltage regulator if you can find them that do away with that fuel economy crap, or a alternator out of a different vehicle that fits that doesn't have that reg. but you would probably then have to worry about the pcm throwing codes. hope that helps.
09-27-2010, 11:25 AM
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I have LS2 injectors out of an '07 Trailblazer SS. I got a whole intake with fuel rails and injectors so I just threw it all on. I topped it off with an LS2 corvette TB, ported and polished, with a Dr. X adapter. Wasn't sure how much of a difference there was between my stock injectors and the LS2's, but my tuner said he could adjust the tune to accommodate them and the TB. I hard wired new harnesses (from Racetronixs) for the different connections straight in, not adapters.
09-27-2010, 11:46 AM
#6
the headlights are not a drain such that you would not be charging the battery or have low system voltage. Just look at your volt gauge if it actually changes, if it is showing 14 or more volts then you're good.
you need to find a service manual or alternator manufacturer info whether it's delco, mando or whoever makes the alternator, and see how they are controlling the voltage regulator. find out how many wires are going to the alternator, other than the main output feed wire. it could be as simple as an extra wire going to the voltage regulator, if it has 5v or 12v or ground on it then it puts it in economy mode.
you need to find a service manual or alternator manufacturer info whether it's delco, mando or whoever makes the alternator, and see how they are controlling the voltage regulator. find out how many wires are going to the alternator, other than the main output feed wire. it could be as simple as an extra wire going to the voltage regulator, if it has 5v or 12v or ground on it then it puts it in economy mode.
09-27-2010, 11:54 AM
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the headlights are not a drain such that you would not be charging the battery or have low system voltage. Just look at your volt gauge if it actually changes, if it is showing 14 or more volts then you're good.
you need to find a service manual or alternator manufacturer info whether it's delco, mando or whoever makes the alternator, and see how they are controlling the voltage regulator. find out how many wires are going to the alternator, other than the main output feed wire. it could be as simple as an extra wire going to the voltage regulator, if it has 5v or 12v or ground on it then it puts it in economy mode.
you need to find a service manual or alternator manufacturer info whether it's delco, mando or whoever makes the alternator, and see how they are controlling the voltage regulator. find out how many wires are going to the alternator, other than the main output feed wire. it could be as simple as an extra wire going to the voltage regulator, if it has 5v or 12v or ground on it then it puts it in economy mode.
There is a two wire plug that goes into the top of the alternator that I have always wondered what it is for........ guess I know now. I'm going to just unplug it for the hell of it and see what happens, like you said, it may throw a code but at least I will be closer to figuring it out.
