c-4 voltage dropping
Thread Starter
Instructor
Joined: Sep 2004
Posts: 166
Likes: 1
c-4 voltage dropping
Hi again
Im having a problem with my voltage at idle I can see the voltage drop from 14.2 or 14.3 to 13 and sometime lower. It seems to only do this at idle and in drive or reverse. Wires plugs just replaced
any suggestions I have no codes
sorry 1994 c4
Im having a problem with my voltage at idle I can see the voltage drop from 14.2 or 14.3 to 13 and sometime lower. It seems to only do this at idle and in drive or reverse. Wires plugs just replaced
any suggestions I have no codes
sorry 1994 c4
Thread Starter
Instructor
Joined: Sep 2004
Posts: 166
Likes: 1
voltage drop
about 1k could this be a split in one of the spark plug wires
also I forgot to mention that Im getting a knocking noise from the drivers side which sounds like a lifter would that be the problem.
Any suggestions at this point would be useful thanks again.
also I forgot to mention that Im getting a knocking noise from the drivers side which sounds like a lifter would that be the problem.
Any suggestions at this point would be useful thanks again.
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
I’m not really sure you have a problem. After running for a while and with the battery fully charged, the voltage will reduce. And if your headlights or A/C is running hard, I have seen my own voltage go the 13.8 or .9 at a light and holding my foot on the brake. After I get going it comes up to maybe 14.1 or so.
Now if you are dropping below 13.5 volts, that may cause reason to pull out the DVM and give it a check at the battery.
I happen to know my displayed voltage is about 0.3 – 0.4 volts higher than the actual battery voltage as read with a DVM. The CCM is not an accurate voltmeter but this is what’s right for my car.
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
I’m not really sure you have a problem. After running for a while and with the battery fully charged, the voltage will reduce. And if your headlights or A/C is running hard, I have seen my own voltage go the 13.8 or .9 at a light and holding my foot on the brake. After I get going it comes up to maybe 14.1 or so.
Now if you are dropping below 13.5 volts, that may cause reason to pull out the DVM and give it a check at the battery.
I happen to know my displayed voltage is about 0.3 – 0.4 volts higher than the actual battery voltage as read with a DVM. The CCM is not an accurate voltmeter but this is what’s right for my car.
Now if you are dropping below 13.5 volts, that may cause reason to pull out the DVM and give it a check at the battery.
I happen to know my displayed voltage is about 0.3 – 0.4 volts higher than the actual battery voltage as read with a DVM. The CCM is not an accurate voltmeter but this is what’s right for my car.
I've also seen may an instrument cluster with a voltage reading that was off by as much as + or - .5 volts. If it gets down below 12 VDC.....you may have an issue. Typically a car only needs a minimum of ~ 11 VDC to continue running - after being started.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
The alternator output (dash voltmeter, engine running) is 14.3 volts cold and this drops to 13.3 volts hot and is normal. The dash voltmeter reads low and is not accurate if the alternator is not charging the battery. It sounds to me that your alternator needs repair or replacement. The dash voltmeter reads low by 0.3 volts because it reads the voltage after the ignition switch contacts which have about 0.3 volts drop. You might check the voltage across the battery terminals. Very low idle rpm, below 600 rpm, will greatly limit the alternator output current and in current limiting the alternator output voltage will be low. A battery that needs recharging can also cause high alternator current. You can tell the state of charge in a car battery by measuring the no load voltage at its terminals, 12.0 volts and below, discharged and 12.9 volts and higher, fully charged and linear in between.
Thread Starter
Instructor
Joined: Sep 2004
Posts: 166
Likes: 1
I did change the pulleys
i did change the ujoints on the drive shaft battery and alt are new and tight connection are made.
No change it affects the idle
also i noticed today that my normal idle is 500 this is when you see the voltage jumping. when driving at rpms of 1K to 2K I get a very bad hesitation. If i step on the gas hard and go past 2k rpms it doesnt happen.
i did change the ujoints on the drive shaft battery and alt are new and tight connection are made.
No change it affects the idle
also i noticed today that my normal idle is 500 this is when you see the voltage jumping. when driving at rpms of 1K to 2K I get a very bad hesitation. If i step on the gas hard and go past 2k rpms it doesnt happen.
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Racer
Joined: Sep 2008
Posts: 487
Likes: 4
I had a similar problem and found a couple of loose ground and positive terminals. Check especially the one at the rear bell housing and ground strap that goes from the bell housing to the drivers side frame. Clean them with sand paper and retorque.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
I did change the pulleys
i did change the ujoints on the drive shaft battery and alt are new and tight connection are made.
No change it affects the idle
also i noticed today that my normal idle is 500 this is when you see the voltage jumping. when driving at rpms of 1K to 2K I get a very bad hesitation. If i step on the gas hard and go past 2k rpms it doesnt happen.
i did change the ujoints on the drive shaft battery and alt are new and tight connection are made.
No change it affects the idle
also i noticed today that my normal idle is 500 this is when you see the voltage jumping. when driving at rpms of 1K to 2K I get a very bad hesitation. If i step on the gas hard and go past 2k rpms it doesnt happen.
