Help 13 Volts, Low Torque
10-19-2016, 06:49 PM
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13 Volts, Low Torque
Hi everyone.
Story:
G37s 6MT '08, everything is fine → somebody breaks my side mirror → 2 month long wait for the new one (car is on the open parking area, battery plugged) → mirror finally arrives → car nearly fails to start because of the battery drain → having issues with foggy windows + on one rainy day car refused to close the doors and shut off interior lights → cleaned water drains and removed water from the battery box at the shop → one day the battery dies (accidentally left headlights on without the engine running), so I bought the new one → feels like I plugged a turbo in it, not just a new battery (at this moment I realized that this is how the car was running when I bought it) → gradually things get back to the previous state (old battery, "no turbo"), but sometimes (on rainy days) car runs just like before the mirror stuff, "turbo mode".
Some technical details:
I bought OBD-dongle to monitor what's going on when the car runs "poorly" and when it "behaves". I can describe two modes:
1) Boring "no turbo" mode, dongle reads 13.3–13.4 V, perceived poor torque on revs under 3.5k, little difference between 50% throttle and WOT, super boring. This mode appears to be "on" on regular basis since after the car was left for two months at the parking lot.
2) As-it-should-be "turbo" mode, dongle reads 14 V, perceived decent low end torque starting from 2k revs, big difference between 50% throttle and WOT, ultra fun. This mode was "on" when I just bought the car, also when I changed the battery (remained "on" for a couple of days) and also when it rains (actual rain is a prerequisite, not just when the rain stopped and it is wet all around).
What has been done:
Guys at the shop checked a lot of wires and connectors under the hood (not sure which ones exactly), all seems okay. Replaced my alternator today with a spare one. Nothing changed, still 13.3 V.
What I plan to do:
In short time I think I'm gonna take away the battery, charge it and then put it back to see what happens (I guess "turbo mode" would be "on" for a couple of days as when I bought the new battery). Even if this works, have no idea what to do later.
Any ideas why this happens and how to overcome this nasty situation?
Story:
G37s 6MT '08, everything is fine → somebody breaks my side mirror → 2 month long wait for the new one (car is on the open parking area, battery plugged) → mirror finally arrives → car nearly fails to start because of the battery drain → having issues with foggy windows + on one rainy day car refused to close the doors and shut off interior lights → cleaned water drains and removed water from the battery box at the shop → one day the battery dies (accidentally left headlights on without the engine running), so I bought the new one → feels like I plugged a turbo in it, not just a new battery (at this moment I realized that this is how the car was running when I bought it) → gradually things get back to the previous state (old battery, "no turbo"), but sometimes (on rainy days) car runs just like before the mirror stuff, "turbo mode".
Some technical details:
I bought OBD-dongle to monitor what's going on when the car runs "poorly" and when it "behaves". I can describe two modes:
1) Boring "no turbo" mode, dongle reads 13.3–13.4 V, perceived poor torque on revs under 3.5k, little difference between 50% throttle and WOT, super boring. This mode appears to be "on" on regular basis since after the car was left for two months at the parking lot.
2) As-it-should-be "turbo" mode, dongle reads 14 V, perceived decent low end torque starting from 2k revs, big difference between 50% throttle and WOT, ultra fun. This mode was "on" when I just bought the car, also when I changed the battery (remained "on" for a couple of days) and also when it rains (actual rain is a prerequisite, not just when the rain stopped and it is wet all around).
What has been done:
Guys at the shop checked a lot of wires and connectors under the hood (not sure which ones exactly), all seems okay. Replaced my alternator today with a spare one. Nothing changed, still 13.3 V.
What I plan to do:
In short time I think I'm gonna take away the battery, charge it and then put it back to see what happens (I guess "turbo mode" would be "on" for a couple of days as when I bought the new battery). Even if this works, have no idea what to do later.
Any ideas why this happens and how to overcome this nasty situation?
Last edited by megafinz; 10-25-2016 at 09:40 AM.
10-20-2016, 11:24 AM
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So after some amount of information digging I came up to a couple of thoughts:
1) Since G37 has variable voltage control system, probably 13.3V on it's own is an okay voltage when the battery is fully charged (though I've seen in some topic that it should be around 13.6V). I observe 14.0–14.1V right after the vehicle is started, and then after a couple of minutes it goes back to 13.3V. Seems like the battery is drained a bit by the starter, so alternator puts 14V to charge it and then rolls back to 13.3V because yay economy. This leads to idea to try to turn off the variable voltage regulation so ECU will always keep feeding 14V to the battery and see what happens.
2) Still unclear why the voltage jumps to 14.0–14.5V on the rainy day. Water causes electricity leak somewhere, so ECU commands alternator to put 14V to charge the battery?
3) Still unclear why 13.3V leads to limpy engine behavior. ECU changes ignition timing? I can log timing trough OBD-dongle, but I have no reference to check whether it's normal or not. Maybe MAFs or O2 sensors start to misbehave, although I don't have a CEL or any error codes present in memory. Another thought is that VVEL or throttle body don't work as they should, but I have no idea how to check that.
1) Since G37 has variable voltage control system, probably 13.3V on it's own is an okay voltage when the battery is fully charged (though I've seen in some topic that it should be around 13.6V). I observe 14.0–14.1V right after the vehicle is started, and then after a couple of minutes it goes back to 13.3V. Seems like the battery is drained a bit by the starter, so alternator puts 14V to charge it and then rolls back to 13.3V because yay economy. This leads to idea to try to turn off the variable voltage regulation so ECU will always keep feeding 14V to the battery and see what happens.
2) Still unclear why the voltage jumps to 14.0–14.5V on the rainy day. Water causes electricity leak somewhere, so ECU commands alternator to put 14V to charge the battery?
3) Still unclear why 13.3V leads to limpy engine behavior. ECU changes ignition timing? I can log timing trough OBD-dongle, but I have no reference to check whether it's normal or not. Maybe MAFs or O2 sensors start to misbehave, although I don't have a CEL or any error codes present in memory. Another thought is that VVEL or throttle body don't work as they should, but I have no idea how to check that.
10-20-2016, 02:13 PM
#3
Registered Member
So after some amount of information digging I came up to a couple of thoughts:
1) Since G37 has variable voltage control system, probably 13.3V on it's own is an okay voltage when the battery is fully charged (though I've seen in some topic that it should be around 13.6V). I observe 14.0–14.1V right after the vehicle is started, and then after a couple of minutes it goes back to 13.3V. Seems like the battery is drained a bit by the starter, so alternator puts 14V to charge it and then rolls back to 13.3V because yay economy. This leads to idea to try to turn off the variable voltage regulation so ECU will always keep feeding 14V to the battery and see what happens.
2) Still unclear why the voltage jumps to 14.0–14.5V on the rainy day. Water causes electricity leak somewhere, so ECU commands alternator to put 14V to charge the battery?
3) Still unclear why 13.3V leads to limpy engine behavior. ECU changes ignition timing? I can log timing trough OBD-dongle, but I have no reference to check whether it's normal or not. Maybe MAFs or O2 sensors start to misbehave, although I don't have a CEL or any error codes present in memory. Another thought is that VVEL or throttle body don't work as they should, but I have no idea how to check that.
1) Since G37 has variable voltage control system, probably 13.3V on it's own is an okay voltage when the battery is fully charged (though I've seen in some topic that it should be around 13.6V). I observe 14.0–14.1V right after the vehicle is started, and then after a couple of minutes it goes back to 13.3V. Seems like the battery is drained a bit by the starter, so alternator puts 14V to charge it and then rolls back to 13.3V because yay economy. This leads to idea to try to turn off the variable voltage regulation so ECU will always keep feeding 14V to the battery and see what happens.
2) Still unclear why the voltage jumps to 14.0–14.5V on the rainy day. Water causes electricity leak somewhere, so ECU commands alternator to put 14V to charge the battery?
3) Still unclear why 13.3V leads to limpy engine behavior. ECU changes ignition timing? I can log timing trough OBD-dongle, but I have no reference to check whether it's normal or not. Maybe MAFs or O2 sensors start to misbehave, although I don't have a CEL or any error codes present in memory. Another thought is that VVEL or throttle body don't work as they should, but I have no idea how to check that.
10-25-2016, 09:39 AM
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UPD: so it seems that replacing the alternator did the trick. Now I read 14.5–14.8V when vehicle starts, and then it backs up slowly to 14.0–14.1V. The power output seems to be back to normal, the vehicle feels fun to drive again.
The only thing that bothers me is that on the first day the alternator was replaced I kept reading 13.3V and getting poor power output. On all subsequent days everything runs okay, though.
The only thing that bothers me is that on the first day the alternator was replaced I kept reading 13.3V and getting poor power output. On all subsequent days everything runs okay, though.
10-26-2016, 07:22 PM
#6
Registered Member
Is between the battery and the fender. Once disconnected, the battery should always stay above 14V while the engine is running.