Anyone seen this? Voltage jump
Thread Starter
Le Mans Master
Joined: Aug 2004
Posts: 5,141
Likes: 7
From: Metairie Louisiana
Anyone seen this? Voltage jump
Most of the time everything is fine but every now and then at idle the voltage needle will jump a bit. This occurs along with a very slight stumble or miss. It's almost unoticeable. Otherwise the idle would be very smooth. It occurs at maybe 2 out of 10 red lights. I'm thinking maybe the IAC needs to be checked, it could be a small vaacum leak somewhere, or maybe a wire arching. I will start checking these out first along with cleaning the MAF again while I'm at it. I think the PCM/voltage is just reacting to whatever else is going on. When have you seen the voltage jump like this? Could an opti going out look something like this? I have 108k miles on the stock one. The car seems to run fine on acceleration, WOT, and highway cruise.
Short video at idle with AC running.
Thanks
Short video at idle with AC running.
Thanks
Burning Brakes
Joined: Nov 2006
Posts: 1,102
Likes: 1
From: Portsmouth Virginia 396LT4 435RWHP/400RWTQ Best so far 11.26 @ 123mph
Rick,
It could be a dirt IAC but sounds more electrical. Did you notice whether the dash lights also flicker in the degree of brightness when engine stumbles? A weak battery could cause this or a suspect alternator on it's way out. Having an electric WP also adds to the load even with our 140 amp alts.As I'm sure you already know, with all the power driven accessories, these cars can be very sensitive to electrical current changes. I also think this symptom would show up more at idle since alt isn't turning as fast reducing current output than it is at speed.
Just a thought.
RG
It could be a dirt IAC but sounds more electrical. Did you notice whether the dash lights also flicker in the degree of brightness when engine stumbles? A weak battery could cause this or a suspect alternator on it's way out. Having an electric WP also adds to the load even with our 140 amp alts.As I'm sure you already know, with all the power driven accessories, these cars can be very sensitive to electrical current changes. I also think this symptom would show up more at idle since alt isn't turning as fast reducing current output than it is at speed.
Just a thought.
RG
Drifting
Joined: Sep 2003
Posts: 1,363
Likes: 7
From: 1994 LT1 Coupe 6-speed with FX3 & 2000 LS1 Vert 6-Speed with F45 Hunterdon County, NJ
I was thinking electrical too.
Can you tell which comes first, the voltage drop or the stumble?
Might also check ground connections -- battery and bell housing.
Can you tell which comes first, the voltage drop or the stumble?
Might also check ground connections -- battery and bell housing.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Normal. Engine stumble at idle occasionally is normal and a drop in rpm may be enough that the alternator runs out of regulation momentarily causing a wiggle in the voltmeter (and alternator output).
