Sluggish performance? Check your alternator!

[Allpar Mod]

I had a shock the other day. I had noticed that the OBW was not performing the way it should, and did, over a couple of days. I initially chalked it up to the heat, though it was not a temperature problem. The temp gauge was where it always sits. The engine hesitated a bit and was sluggish especially with the a/c on. I thought that there was a tune up issue developing as that's the way it felt.

 

Well, on the way home from shift Monday, I noticed a few times it acted like there was an electrical issue developing now. The gauges fluctuated wildly with any extra draw, like turn signals or brake lights. Finally it died at a stop light at the end of an exit ramp. The battery was dead. The wife brought me out another battery I had from the Jeep I'm reconditioning and I got it home.

 

At hoime, I checked the charging system and the alternator had crapped the bed. It was only registering 11 volts with the charged Jeep battery. I charged the OBW battery and it came back 100% including a load test.

 

Side note.....obviously my low voltage indicator is not functioning. Another issue entirely. I'm installing a gauge in a pillar pod after shift today.

 

So, the moral of the story is low voltage can and will effect performance. It doesn't hurt either to check that your idiot lights work also.

[davebugs]

Often you loose the high RPM's first. And look for something like a fuel delivery problem, plugged cat, etc.

 

Now I've learned to check the alternator first. Never has been fuel delivery or a cat.

[nipper]

Sometimes people ask me why I ask about alt output, but without good output that entire sparkly thing doesnt work well.

 

It is also something to check when diagnosing any wierd fuel or temp gauge issues.

[Rooster2]

Thanks for the write up. Learn something new every day!

[bheinen74]

wasted spark coils packs, are very tempermental to voltage inadequacies. I like the voltmeter on the older subarus, i feel it was a beneficial guage and i constantly monitor it. otherwise, blinky lights also are a sign on the new ones, the xmas tree effect we call it on bbs.legacycentral board

[Allpar Mod]

I was going to install an ampmeter I have in it today, but decided instead to install a voltimeter when I have a chance to pick one up. Easier to install and I believe more telling of what is going on at a glance.

 

By the by, I just noticed that the idiot light is working again. I went outside to roll up my windows as it may rain and just turned on the ignition to roll up the power windows. The idiot light was staring me right in the face big as life as it should with the ignition on but not started. I thought that this car has had a gremlin or two in the past. Now, I'm convinced. Either that or the telltale is tied in directly with the alternator circuit rather than just reading the voltage and the bad alternator was faking the circuit out. Never seen anything like this before.

[CNY_Dave]

An ammeter that uses a very low resistance resistor is pretty easy to install if anyone really prefers an ammeter (it's a voltmeter that goes across a low-value series resistor).

 

Dave