Weird electrical problem maybe? Imput please

**jlyv3845** · 05-05-2008 09:13 PM

It's pretty simple; whenever i lay off the gas and especially at around 2100 rpms, the car has like an electrical slouch where the headlights kind of dim a slight bit and the interior lights/dash as well. It's so strange, almost like a minor surge, or a weird semi-power loss. No CEL's or any problems, and it's still stock. Looking for some imput as to what this mysterious problem could be. Thanks in advance.

Josh

**RolledMySTi** · 05-05-2008 09:50 PM

You alternator could be seeing its last days.

**jlyv3845** · 05-05-2008 10:23 PM

wonderful...cost to fix/replace?

**amd is the best** · 05-05-2008 10:24 PM

I would also say that it would be charging system related. Alternator, possibly even your battery is getting weak. You may also want to make sure that your termials are good and clean and that your grounds are all secure.

Nick

**jlyv3845** · 05-05-2008 10:47 PM

thanks for the impute, and ya that's definitely a possibility but i replaced the battery maybe 2 months ago and made sure everything was all good and clean. So i'm thinking it's probably not that, any other ideas?

**AMC** · 05-05-2008 11:07 PM

input*

**jlyv3845** · 05-05-2008 11:35 PM

oh wow ya my bad, amend that. 1 am sighhhh

**obijohn22** · 05-06-2008 05:21 PM

If it is an alternator problem you will likely see it on the volt meter on the dash next to the speedo, watch the gauge when this happens wee if the voltage drop is measured there. Are you a tip or manual? Is the car trying to downshift at this RPM? If so, it could be related to a severe drop in RPM due to trans issues. Does it do this in every gear? or only when coming to a stop? Also, does it do this with just the parking lights on or only when the headlights are on? Lastly, check the codes.

**kingofqueenz788** · 05-06-2008 08:41 PM

im pretty sure you can put a volt meter 2 the 12V source on the maf wire which should be green in a 2000 s4 it varies wit the hitachi mafs, and you will see what the alternator is charging the car at it should be 14.5 volts bec thats what the alternator charges the car at when on. if its lower then that while standing still when the car is on your alt is on its last leg also go up under the car and volt meter the starter wires. i noticed when i am trying 2 fix my maf problem bec i was like y is my volts at 14.5 and not 12

**jlyv3845** · 05-06-2008 09:22 PM

Originally Posted by obijohn22

If it is an alternator problem you will likely see it on the volt meter on the dash next to the speedo, watch the gauge when this happens wee if the voltage drop is measured there. Are you a tip or manual? Is the car trying to downshift at this RPM? If so, it could be related to a severe drop in RPM due to trans issues. Does it do this in every gear? or only when coming to a stop? Also, does it do this with just the parking lights on or only when the headlights are on? Lastly, check the codes.

Am i looking for substantial movement on the volt meter or just a tick? I have the 6 speed so the car isn't trying to downshift. It does it w/o the headlights on but it's just more noticeable with the change in interior and headlight light at night. Sorry can't check codes...don't have the hardware.
It only really likes to do it at about 2100 in 3rd gear and also on the upshift 3-4 when the revs drop to ~2000. It's sporadic on the highway, but never does it when accelerating. The only other time i can really remember it doing this before the problem really exasperated was when i would roll into the garage and right when i came to a stop it would have an "electrical slouch." Maybe the alternator? The car is going in for 60k (TB, water pump, etc) and much needed alignment and DV's next week so i'll have the place (not dealership, thanks to all who recommended ESP) check this out as well. Any other thoughts?