Charging Issues
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Joined: Jun 2015
Posts: 72
Likes: 15
From: Honolulu
Charging Issues
Aloha gang,
Had to sign in with facebook. Don't remember my password here, cant reset because I don't know my old Hotmail. password to reset this one, lol
Any how, I have a 06 z51 6 speed manual. Big cam, headers, intake.
Also have an underdriven pulley and electric water pump. Now just recently, if im in heavy traffic, my volts go down to 11,9 if I sit to long. Then the a/c will cut off. If I sit longer the car starts to overheat and the water will boil off in the reservoir. This can all happen in just a few mins. Im thinking the PCM is cutting off the water pump when its cutting of the a/c. So is my alternator going out, or should I just get rid of the electric water pump. Sorry this is long.Trying to give a good detailed description of the event,
Thanks
Had to sign in with facebook. Don't remember my password here, cant reset because I don't know my old Hotmail. password to reset this one, lol
Any how, I have a 06 z51 6 speed manual. Big cam, headers, intake.
Also have an underdriven pulley and electric water pump. Now just recently, if im in heavy traffic, my volts go down to 11,9 if I sit to long. Then the a/c will cut off. If I sit longer the car starts to overheat and the water will boil off in the reservoir. This can all happen in just a few mins. Im thinking the PCM is cutting off the water pump when its cutting of the a/c. So is my alternator going out, or should I just get rid of the electric water pump. Sorry this is long.Trying to give a good detailed description of the event,
Thanks
Race Director
Joined: Aug 2005
Posts: 13,592
Likes: 187
From: Hudson WI
NCM Sinkhole Donor
How old is the battery? Also you have an underdrive pulley, so you are killing the battery because you are running the car on the battery because the alternator can not keep up. The battery is made to start the car, not run the car. I installed a Billet Tech alternator when I installed my underdrive pulley to get the amps back that I lost.
Race Director
Joined: Dec 2013
Posts: 12,502
Likes: 3,628
Car idling,
Multimeter set to DC at least 20V.
What is the voltage at the battery, connecting the multi meter probes to the battery lead posts directly.
What is the voltage of the alternator, connecting the positive probe of the multimeter to back threaded post of the alternator under the rubber cover, and the negative probe directly to the alternator body itself.
What is the voltage from the positive post on the engine fuse block terminal (lift the block lid) with the negative probe to the body of the alternator body.
What is the voltage reading of the DCI when you toggle it to voltage.
Multimeter set to DC at least 20V.
What is the voltage at the battery, connecting the multi meter probes to the battery lead posts directly.
What is the voltage of the alternator, connecting the positive probe of the multimeter to back threaded post of the alternator under the rubber cover, and the negative probe directly to the alternator body itself.
What is the voltage from the positive post on the engine fuse block terminal (lift the block lid) with the negative probe to the body of the alternator body.
What is the voltage reading of the DCI when you toggle it to voltage.
Melting Slicks
Joined: Jul 2005
Posts: 2,649
Likes: 863
IF you are sitting with the car idling, and the voltage drops to 11.9 volts - you are in a situation where the alternator is turning too slowly to provide the electricity to keep up with the demand...
So - when that happens - depress the throttle very slowly - and see how fast you have to turn the motor to get the voltage up to at least 13 Volts (sometimes you need to rev the engine to "wake up" the alternator to get it charging again - if that is the case - then you can note how high you need to keep the RPM to keep the voltage at 13 Volts or more. Even with an underdrive pulley set-up - you should be able to maintain 13 volts at a little over 1,000 RPM. If you have to go much higher than that - it's quite possible that your alternator is on it's last legs.
The PCM is able to turn off the A/C compressor if the voltage drops too low - but it can't do a darn thing about the water pump unless you wired the new electric water pump to some circuit that the PCM controls. Obviously, too low a voltage to the electric water pump means the Water Pump motor is turning slower, and therefore not pushing coolant through the engine and cooling system at the advertised rate - but even at 11.* volts - I would expect that there would be enough flow to match what the OEM pump is flowing at idle, so the overheating you are experiencing is a little bit surprising. I agree with Dano523 - check the voltage at the alternator output, and at the battery - and at the water pump to see if you are experiencing voltage drop somewhere.
I would not be thinking about going back to the mechanical water pump just yet - the problems you're seeing just don't seem to point that way - do some diagnostic testing first.
GOOD LUCK !
So - when that happens - depress the throttle very slowly - and see how fast you have to turn the motor to get the voltage up to at least 13 Volts (sometimes you need to rev the engine to "wake up" the alternator to get it charging again - if that is the case - then you can note how high you need to keep the RPM to keep the voltage at 13 Volts or more. Even with an underdrive pulley set-up - you should be able to maintain 13 volts at a little over 1,000 RPM. If you have to go much higher than that - it's quite possible that your alternator is on it's last legs.
The PCM is able to turn off the A/C compressor if the voltage drops too low - but it can't do a darn thing about the water pump unless you wired the new electric water pump to some circuit that the PCM controls. Obviously, too low a voltage to the electric water pump means the Water Pump motor is turning slower, and therefore not pushing coolant through the engine and cooling system at the advertised rate - but even at 11.* volts - I would expect that there would be enough flow to match what the OEM pump is flowing at idle, so the overheating you are experiencing is a little bit surprising. I agree with Dano523 - check the voltage at the alternator output, and at the battery - and at the water pump to see if you are experiencing voltage drop somewhere.
I would not be thinking about going back to the mechanical water pump just yet - the problems you're seeing just don't seem to point that way - do some diagnostic testing first.
GOOD LUCK !
