Jump to content
SAU Community

Symptoms Of A Bad Alternator

Crans

By Crans,
in Engines & Forced Induction

 Share

Recommended Posts

Crans Mentor

Crans

Posted
Posted

I am pretty sure my alternator is stuffed.

The start of the problem, apart from car generally running like crap.

Installed a new turbo, this took weeks due to excessive beer drinking while working and having custom intake pipes made, forgot to disconnect battery for some of this time so it went flat.

Jump started car. First attempt mate had + and - around the wrong way = epic fail and sparks.

Got car running apart from rough and lean idle and extreme lag all good.

I went away for a week in march and battery went flat again. Took it for a 10 minute drive. Parked for 10 minutes car had to be push started.

Then took it for a 1/2 hour drive and this was enough to charge the battery for the next start.

Next day battery is flat. Replaced battery. New battery went flat shortly after. charged and it hasn't gone flat since.

Now the big thing pointing me towards a stuffed alternator is the idle goes very rough and very lean when the lights are on.

Found this out going through maccas drive through(Never drive my car at night so first time i noticed his)

As a test on the way to work today i turned the stereo and all accessories off and the idle fueling was actually sitting quite normal around 14.7 - 15

So basically how do i test the alternator and is there any common R33 problems, like a bad earth or something like that before i go looking for a replacement.

Also consult showed idle voltage as around 12v dipping sometimes to 11.9v, really though this should be more like 13v - 13.5v

Also could the lack of power be causing a very laggy car? I was thinking not enough power to coil packs causing a weak burn?

What are the options on replacement? will a rb30/rb20 one fit?

Cheers for the help and sorry for the lengthy crap filled post.

Link to comment
https://www.sau.com.au/forums/topic/322925-symptoms-of-a-bad-alternator/
Share on other sites
jrm Veteran

jrm

Posted
Posted

Voltage at idle should be anything from 13.5-14.4V, if you're only seeing 11.9V or so, there's definitely an issue with the alternator, and it's probably not adequately charging the battery either.

I'd be talking to an auto-elec and get them to check it out. I wouldn't be surprised when you had the connections back to front when jump-starting it fried something in the alternator.

Either way, shouldn't be too expensive to replace or recondition to fix it up.

Boosted Mayhem Rookie

Boosted Mayhem

Posted
Posted

One of two things could have probably happened.

One, you fried a fused link in the wiring (if Japanese cars have them). Or, you have fried the internals of the alternator itself due to having the jumper cables on the wrong posts.

Also, if your battery goes dead, it's best to charge it fully before starting it. Some alternators have issues with trying to fully recharge a battery and can cause them to go bad. Had this happen eons ago with my first car. Batt went dead, jumped it and left it running for a while to recharge it and ended up frying my alternator. Went through two alternators before I went to a shop that told me what was going on. (Damn GM cars of the 80's...lol)

Would be a good idea to get a new alternator and make sure the battery is fully charged. If you are still having issues after that, you probably have a constant power somewhere sapping your battery's juice. A good earthing kit would be a good idea too.

gelousi Collaborator

gelousi

Posted
Posted

Yeh check fuses in the bay you might have blown a fuse when connecting the polarity the wrong way around also get a multimeter test from earth anywere and to the posotive terminal on the back of the alternator, im pritty sure its a thick white wire coverd by a black gromet with a 12mm nut see if your getting power there if not then there is a break in the circut from that to the battery

Brezza Proficient

Brezza

Posted
Posted

mate,

sounds like its your fusable link.

on my GTR i put the terminals on the wrong way round because i used my brothers battery out of his car to start it. fried the fusable link. could tell because no lights or accessories would work, just the engine would run.

got an auto elec to fix, remade link. lasted about a year, then recently it was burning out slowly, prob because it wasnt a strong enough link for the replacement. the power steering was cutting out, then the guages didnt work, so i couldnt tell how fast i was going, it was really bad. then the battery went flat.

so what was happening the car ran the battery completely flat and the alternator couldnt charge because the link was broken.

get the link fixed, its only a cheap part, i think it was $50 from nissan.

and remember, next time 'Don't connect the battery the wrong way round'

good luck

Crans Mentor

Crans

Posted
  • Author
Posted

Wasn't me that connected the jumper leads ;) I can safely say i have never been that stupid.

New battery has been running fine for the last 3 months. So problem is low running voltage. Could this still be the fusable link?

Brezza Proficient

Brezza

Posted
Posted

yeah its a pretty stupid thing,

not sure whether it could still be the fusable link?

i am not a mechanic, was just telling you what my experience was with a similar issue.

prob need to check with a auto elec or someone with tools to check it with a multimeter or something?

Jaredo Explorer

Jaredo

Posted
Posted

I'd take the alternator to a auto sparky. Probably borked the regulator with the swapped post mishap. Pretty sure they can do load tests ect to find out the cause.

I've had a flat battery and roll started the car to get it going and it ran quite rough so yeah not enough power would be causing the rough idling you seeing.

lookingforboost Community Regular

lookingforboost

Posted
Posted

my sil played up like this for ages before i worked out what was going on, i put new terminals on new earth leads (thicker) and got the alternator rebuild it was something to do with the reg, then the car was so much better to drive smooth and even felt like it had more power!

  • 14 years later...
silviaz Experienced

silviaz

Posted
Posted
On 6/1/2010 at 11:16 PM, Rekin said:

I had a rough idle when I had lights on. Ended up replacing with a rebuilt alternator and good as new!

Did you find that your voltage of the battery wasn't where it's normally supposed to be? for example on my r34, it's at 14.5v when running after a few seconds, but I noticed when I had a rough start and it initially wasn't idling correctly, the voltage on my triple gauge cluster was showing lower than usual. Seems like the alternator is starting to crap itself

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • GTSBoy
      Boost cut after swap(RB25DET NEO) R34

      By GTSBoy · Posted

      Don't even try to run it on the stock ECU if you're going to have the boost controller bring boost above ~10 psi. I've already told you that. If you use the Nistune ECU, you will need to CAREFULLY read the available documentation for Neo tuning, and read some threads on the Nistune forums, to discover the various things you have to do to prevent the ECU from going bananas when the boost is too high. The is a table associated with th boost sensor that must be modified to prevent it from shitting the bed. This is just one of the things that you will need to do to the tune in Nistune, because the Neo turbo ECU will be expecting to see a number of things (such as the TCS) that are not there, and you have to block the DTCs on those. It is totally not surprising to me that you are having the problems that you are, but the solutions to these problems have been known for >15 years. So just get it done.
    • dyl33
      VOLK RACING GTC CENTRE CAPS

      By dyl33 · Posted

      Centre caps $250
    • Kapr
      Boost cut after swap(RB25DET NEO) R34

      By Kapr · Posted

      Hi. Sry iam not a mechanic and iam not at the car atm so i dont know 100% but they told they measure those and even try to change those. AFM they have two. Coils are new a they have my old one too. Plugs too. ECU...we have 25 NEO stock and Nistune 25 NEO.   But i dont know if any one those could be the problem and why/if/what can cause this, Only thing they did not check is fuel...but that walbro 255 is new(like 1,5 years)... That fuel pressure gauge idk...but i let them know Any suggestions?   EDIT: how can they know if it is like you say he ECU pull power when it reaches a specific boost level that is too high? Tha car has boost controler
    • Duncan
      Boost cut after swap(RB25DET NEO) R34

      By Duncan · Posted

      Can you clarify what you mean by boost cut, do you mean it misfires both when under load (driving) and when stationary and out of gear? Or does the ECU pull power when it reaches a specific boost level that is too high (boost control issue)? Does it occur at idle with no throttle? When you say "the ECU is OK", what ECU is it and why do you think it is OK? Have you used the NEO ECU, and if so do you have a MAP sensor attached? Same for the AFM, why do you think it is OK? Do you have any way to put a fuel pressure gauge on it (even just a mechanical one between the fuel filter and fuel rail)?
    • Kapr
      Boost cut after swap(RB25DET NEO) R34

      By Kapr · Posted

      Hi.. Just another problem. So maybe you can help. I(my mechanic) done swap from my RB20DE NEO to RB25DET NEO. Everything is OK but we have a boost cut. Coils/Plugs are ok...AFM is ok. ECU is ok. I have Walbro 255 but it "changed" sound few months ago(you can hear it ouside) you did not hear that when it was new(maybe faulty?) Sooo...what now? What can cause this boost cut? It is even when you standing still...
×
×
  • Create New...