Jump to content

The RennTech.org community is Member supported!  Please consider an ANNUAL donation to help keep this site operating.
Click here to Donate

Welcome to RennTech.org Community, Guest

There are many great features available to you once you register at RennTech.org
You are free to view posts here, but you must log in to reply to existing posts, or to start your own new topic. Like most online communities, there are costs involved to maintain a site like this - so we encourage our members to donate. All donations go to the costs operating and maintaining this site. We prefer that guests take part in our community and we offer a lot in return to those willing to join our corner of the Porsche world. This site is 99 percent member supported (less than 1 percent comes from advertising) - so please consider an annual donation to keep this site running.

Here are some of the features available - once you register at RennTech.org

  • View Classified Ads
  • DIY Tutorials
  • Porsche TSB Listings (limited)
  • VIN Decoder
  • Special Offers
  • OBD II P-Codes
  • Paint Codes
  • Registry
  • Videos System
  • View Reviews
  • and get rid of this welcome message

It takes just a few minutes to register, and it's FREE

Contributing Members also get these additional benefits:
(you become a Contributing Member by donating money to the operation of this site)

  • No ads - advertisements are removed
  • Access the Contributors Only Forum
  • Contributing Members Only Downloads
  • Send attachments with PMs
  • All image/file storage limits are substantially increased for all Contributing Members
  • Option Codes Lookup
  • VIN Option Lookups (limited)

Surging revs, voltage fluctuating, instrument lights dimming


Recommended Posts

Guys,

Am having some strange issues with my 2001 Carrera4.

The car has sat for several weeks, with me starting it for a few minutes every week or two.

Now that I finally am able to drive it, I took her for a mellow ride (as opposed to driving like i stole it)

Everything seemed fine until after a few miles of driving at operating temp, several of the dash warning lights came on.

So, I drove it the few blocks back to my house... the whole time everything felt fine.

Turned the car off, checked fluids, hooked up a meter to battery. Everything looks good.

Minutes later I decided to turn her back on, and I get what is in the video linked below...

RPM is constantly surging, the voltmeter in the dash is going from about 11-11.75, several of the warning lights are on, and the instrument lights that are on will dim with the RPM surges.

After that I have noticed that with the key in the ignition, but with the car off, voltmeter shows about 11/11.5.

Check with my handheld meter on the battery it shows just above 12 volts...

Battery is about 3-4 months old.

Any pointers? I am really jonesin to drive her.

Also I should mention, I am suspicious of the accuracy of my handheld meter... it is a cheap one, and several years old.. though seems correct on my other cars.

Thanks

Link to post
Share on other sites
    You can remove these ads by becoming a Contributing Member.

  • Moderators

It looks like you have a failing alternator, or at least a dying voltage regulator. Car should have around14V running and high twelve’s off.

Edited by JFP in PA
  • Upvote 1
Link to post
Share on other sites
  • Admin

Start by double checking your battery by measuring the specific gravity of each cell and a load test.

If it checks out then you are looking at an alternator or the voltage regulator on the alternator as bad.

BTW... normal charging (engine running) is about 13-14 volts.

  • Upvote 1
Link to post
Share on other sites
  • 4 weeks later...

For anyone who found this post via searching:

Replacing my alternator did fix the problem... and if you have to change the alternator, you might as well do the belt at the same time.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.