Alternator bad?

[Rob98GST]

Well, I leave work today and my car doesn't start - won't turn over anything. So I get a jump pack and get it started. I think I guess I left my lights on. I get about 50 yards down the road and it dies again as I let off the gas. I am starting to get a little worried now.

I jump it one more time and get a little farther this time and it dies again. Well, this time I have to call my wife to bring me a battery. Well, while I am waiting a few people stop and tell me that they are pretty sure it's a bad alternator.

The car starts right up with the new battery and my jomptronix voltmeter is reading a good 14.1 or so at first. On my 15 miles ride home the volts are anywhere from 13.8-13.5, where they should be. But I have to keep the revs up around 2.5-3k to keep it running. The one time I did let it drop, it almost died.

I get home and I let it idle for a minute or so and the rev's are at around 200 or so barley running. I disconnected the battery when I get home.

Does this sound like a bad alternator? Even though the voltage on my voltmeter read 13.5+ the entire 15 miles home? My battery cables are a little dirty, but not bad at all.

Any ideas would be appereciated. Thanks.

 

[2gPressure]

revs are at 200? your rpms?

My alternator did about the same thing, it would work and charge only at certain engine speeds. I had it checked at Autozone for free, which you can do, and it would only work at higher rpms. i hope that doesn't help. jk

 

[Rob98GST]

revs are at 200? your rpms?

Yeah - rpm

Okay, I was pretty sure it was something with the alternator... I had my 1g brand new up until I sold it with 188k and never had an issue with the alternator and my 2g only has 69k on it

Thanks.

 

[TurboDSM86]

Well, I leave work today and my car doesn't start - won't turn over anything. So I get a jump pack and get it started. I think I guess I left my lights on. I get about 50 yards down the road and it dies again as I let off the gas. I am starting to get a little worried now.

I jump it one more time and get a little farther this time and it dies again. Well, this time I have to call my wife to bring me a battery. Well, while I am waiting a few people stop and tell me that they are pretty sure it's a bad alternator.

The car starts right up with the new battery and my jomptronix voltmeter is reading a good 14.1 or so at first. On my 15 miles ride home the volts are anywhere from 13.8-13.5, where they should be. But I have to keep the revs up around 2.5-3k to keep it running. The one time I did let it drop, it almost died.

I get home and I let it idle for a minute or so and the rev's are at around 200 or so barley running. I disconnected the battery when I get home.

Does this sound like a bad alternator? Even though the voltage on my voltmeter read 13.5+ the entire 15 miles home? My battery cables are a little dirty, but not bad at all.

Any ideas would be appereciated. Thanks.

I'd suggest checking your alternater output by using a DVOM and checking voltage output by going from the top of the alternator where the cable goes to and to you battery. It should be 13V or in that range. My 2g did the same thing as yours. If i was driving it was ok. When id come to a stop it would want to die. I replaced my alternator after verifying it was bad and havent had a problem since.

 

[2gPressure]

That 200 rpm is confusing, it shouldn't do that with a bad alternator and a good battery in. You should try running it for a while with a fully charged battery and disconnect the alternator. if you still have problems you might want to look somewhere else. I beleive there is something called an engine load controller that may control the alternator. just try a charged battery with no alternator. I drove home almost 200 miles on a fully charged battery and bad alternator. and it ran and idled fine till the battery died.
good luck

 

[Rob98GST]

Oreilley's can get me one with a lifetime warrenty for $119 + core.

A DVOM? I am guessing thats a voltmeter of some type? I just have my jumptronix, but I am sure the alt's bad from you describing the same symptoms.

Thanks guys! I really appreciate the help

 

[me612]

Check your voltage at the battery terminals while the car is running. If you are reading under 12V with the engine running, then you are running off the battery and there is something more then likely wrong with the alternator or the wiring to it.

 

[MNGSX]

If it died above 13v... Check the pwr transistor... Bench test your alternator first.

 

[Rob98GST]

If it died above 13v... Check the pwr transistor...

What is the pwr transistor and how do I check it?

I plan on having the alternator tested before I buy a new one.

 

[Rob98GST]

This morning it started right up, volts at around 14.15. I let it idle for a little while and it all seemed okay. I even took the negative battery cable off and it ran fine, I even truned on all the lights, etc - still okay, as I started to back out of the garage I hit the brakes and the rpm went down to around 200 again and the volts droppped to around 13.20. So I pulled it back in the garage and the volts now were around 12.6 ish. So I decide to get a new alternator.

Well, tried the new alternator and thats not it - doing the same exact thing. With the new alternator I did the same thing taking the negative batt. cable off, turned the lights on, hit the brakes, etc. Everything is fine until I put the car in gear and start to move a little bit, as soon as I take it out of gear the rpms drop and the volts start to fall.

Anything thoughts? I am about ready to just bring it to the dealer...

 

[MNGSX]

www.vfaq.com


Check your pwr transistor after it has died.. It is the ignitor or the coil driver. The service manual has a proceedure...

 

[drag97GSX]

I am still confused about the whole 200rpm thing. My factory 2g tach STARTS at 500rpm. Now assuming you mean it is dropping down to 600-700rpm (second tick on factory tach) then your alternator would have a hard time making any output. It simply wouldn't be spinning fast enough. A problem my car has always had after any lengthy period without power (disconnected due to working on car or dead battery) is that my ECU needs a couple of drives to reset itself. It almost never picks up idle after i get it started up. The only thing i do is run it down the highway to a few stop signs and just keep blipping the throttle when stopped. Usually by the time i get home it has sorted itself out. Sorry i couldnt be of more help...good luck.

 

[blue92laser]

Replace the spark plugs, believe me there is a good motion for it.

 

[Rob98GST]

I am still confused about the whole 200rpm thing. My factory 2g tach STARTS at 500rpm. Now assuming you mean it is dropping down to 600-700rpm (second tick on factory tach) then your alternator would have a hard time making any output. It simply wouldn't be spinning fast enough. A problem my car has always had after any lengthy period without power (disconnected due to working on car or dead battery) is that my ECU needs a couple of drives to reset itself. It almost never picks up idle after i get it started up. The only thing i do is run it down the highway to a few stop signs and just keep blipping the throttle when stopped. Usually by the time i get home it has sorted itself out. Sorry i couldnt be of more help...good luck.

I drove it home on the highway - about 13 miles of it were highway, but once I got in the city, it kept wanting to die on me. I'll look into the pwr transistor and I'll try new plugs, but I just changed them not 10k ago.

Yeah, it was around 700 rpm is what it would drop to. Like I said before, it idled fine when I turned the lights on, radio, etc, but when I put a load on the car (put it in reverse) and moved is when it seemed to have to drop in RPM.

I am going to work on it more tonight, but I am I am sure it's something simple.

 

[Rob98GST]

Well, it ended up being a bad ISC motor(they called it the air idle control motor). Thats all the dealer could find wrong with the car.

They quoted me at $275 for the part!

I've heard that you can sometimes just clean these out - anyone had experance with this?

The dealer also gave me some BS about when you install the ISC motor, you have to have some other crap set and that you need special equimpent to set it right.

I was talking to one of the mechanics and it was first time I heard someone who worked for mitsubuishi mention that some of the 95-96 eclipse turbo's having problems with crank walk...