Alternator going out?

[2GeNTSi]

Ok here we go another problem to fix on my car, of course not the last. Here is the problem, just the other day I was getting off work and I went outside to get in my car and warm it up. I start the car and I listen to the radio while just chillin waiting for it to go above C. And so about 30 secs later I notice the idle start to become irratic (sp?) going up and down going as low as 400rpms. After it warms up I put it in reverse and start to back-upm I noticed that after I let off the gas the idle dropped pretty low and the lights got a bit dim. I made it home fine, runs the same and power still in tact.

Today I cleared my CEL that I had thinking it might be the culprit but it was just my 2nd o2 going crazy because of the downpipe. I drove to work and it idled normally but every so often at a stop it would go a bit lower then usual. Fast-forward to the end of the night, I decide to take a look at the voltage reading on my TT, and as I'm driving I would get 14v but during idle I would get only around 12.5v. Last time I took a look at the voltage reading it read 14v at idle if I'm not mistaken.

Also some other things that might point it to the alternator as well. Sometimes when I take the key and let the car idle, the TT would just shut off. Before I got my new battery, every now and then the car wouldn't start, all I would hear was a loud click and the gauge lights would get dim (disconnecting the negative on the battery and putting it back on remedied it). What was weird with the battery though was that for some reason it wouldn't start after installing my fuel pump, it would start when jumped though, I got it tested and it was still good just a little low on voltage so I charged it. A couple months later it died again so I just bought a new one and it started fine.

I'm going to take a look at my alternator tomorrow, I'm leaning more towards this as the problem. What do you guys think?

 

[Rick4g63]

I had a similar problem after I installed my new battery.

The Fix: The negative terminal on the battery was loose. It was tight enough to start the car, but the vibration "loosened" it, causing the alternator not to properly charge the battery.

- While the car is idling, place a volt meter across it and measure the voltage reading (12.9 to 13.5 volts is acceptable.

- With the volt meter still connected, rev the car, a reading of 13 to 14.5 volts is accepatable.

- With the car idling, remove the negative terminal of the battery, if the car dies the alternator is not "putting out" voltage to charge the battery.


Keep us informed

 

[2GeNTSi]

I did all three, everything came out fine, voltage was at 14v at idle and when revved up. The car still ran when I removed the negative terminal. I'm going to keep a voltmeter with me next time I drive it to test it when it acts up.

 

[Trizon]

sounds a lot like my alternator problem.. I had recently just re-installed my rebuilt motor, but gauges, turbotimer, and radio didnt wanna turn on.. at first like an idiot all I noticed was my expensive flipout touchscreen and assumed it shorted out.. I checked the resistor and tried to find out what was wrong, we eventually found out it was a bad alternator not providing enough voltage, we only found out due to us having to recharge the battery 3 times.. -- once I replaced it, was fixed.

 

[2GeNTSi]

Just viewed my front and rear o2 in park while revving up, they are getting readings. Also I noticed that one of my belts are squeaking, maybe the alternator belt?

 

[2GeNTSi]

Alright I woke up early to work on my car, I took off the alternator, took me like 2 hours to do. I removed the drivers side fan and the four bolts on the ps pump. After doing it all I realized I didn't even have to touch the ps pump...anyways I brought it to Pepboys and Autozone and for some reason they didn't have the connector for it so I took it apart and I didn't really know what I was looking at so my dad helped me and he noticed that the brushes were worn (you couldn't see the whole logo of the diamond star).

I put it back on because I need the car tomorrow for school, I took it for a drive, still runs fine but idles low. I'll prob try to order it on Wed but I'm curious because all the places I called don't have it in stock so I have to order it, and orders you usually cannot return. I'm scared that if I order it, it won't be the correct one.

 

[2GeNTSi]

Ok been a while since I updated but I got pulled over the other day and now I have to get my car smog refereed. Sooo I had to put every performance part back to stock, the only thing not stock is the fuel pump right now. I also received the remanafactured alternator from Autozone the other day. I put it in and the car started fine, the rpms started out a bit high around 3k and then it started dropping and got really low. Then it started being erratic and eventually died.

I checked for any sort of vacuum leak from any of the areas I touched and none. The only vacuum lines I touched were the one going to the bov and the bcs lines (believe they would only affect the car under boost) but they are all intact. I got my core back and put it on thinking it might be that and it still does the same thing.

I'm getting an alternator from Napa Auto today, they come from Rancho Cordova rebuilt so I hope this will fix it.

 

[Warhead2k3]

Are all of your honeycombs in the intake?

 

[2GeNTSi]

Yeah I haven't touched the maf. But anyways I got the new alternator in and it is still doing the same thing. Although I tightened up the throttle cable and it doesn't seem to do it as bad.

Also it was weird, my dad was taking a look at the car as well and he left the MAF unplugged. I started it without knowing and it kept idle on its own fluctuating between 900-1000. I'm not sure what it can be at this point...possibly the ECU? I've never heard of the ECU going bad on 2gs though, but we did replace the ECU on my bros 3/S VR-4 and it is running again.