19 volts at the battery?!? | FerrariChat

19 volts at the battery?!?

Discussion in 'Boxers/TR/M' started by chabch, Mar 8, 2016.

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  1. chabch

    chabch Formula 3

    Aug 15, 2010
    1,075
    France
    Full Name:
    Christophe
    Hi everyone,

    I need some help...

    My alternator died a few months ago and I replaced it myself, although not an expert. Once I was done, I started the car and measured 14.1V. The battery light on the dash that used to be on was now off. That was a few weeks ago.

    This weekend, I decide to take the TR out for a drive, and when I started it I felt like I was missing cylinders, but a second or two after it was running fine. It was the first time it did that, it always started on all cylinders right away. I let it warm up a little and go. Getting out of the house I felt it slow to rev of idle, running a little rough, but then once past 1500 rpm it seemed fine. Once at running temperature, it seemed fine (even at idle) for about 15 minutes but then started running rough again at low revs. I just went back home and parked it in the garage.

    I once had a coil failing and it felt similar, so I thought it was the other one going bad. This afternoon I checked if I had sparks and it looked fine. I tested the ignition using a little electronic device that tells me if the spark voltage is low/correct/high and they all checked fine.

    A then noticed that it didn't seem to be stumbling from one side or the other, which would confirm that it is not once of the coil. it runs rough, then ok a little for a second or two, then rough again. Oh, and it smell like gas from the exhaust and I see little drops on the floor.

    Now, here is the weird thing...

    I put a volt meter at the battery. The car off I have 13v, the car on I have 14.1v. So far so good, then then out of nowhere it goes to 18v! Even as high as 19.5v!! Obviously I did not leave it on very long at this voltage, afraid of burning things all over the place.

    Any idea what could be happening!?

    Could have I done something wrong mounting the new alternator? Did I run lower voltage than normal when the previous alternator died and burned regulators or something?

    Help! :)
     
  2. BigTex

    BigTex Seven Time F1 World Champ
    Owner Rossa Subscribed

    Dec 6, 2002
    79,143
    Houston, Texas
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    Bubba
    The voltage regulator (internal to the alternator) is failing.

    You are correct, in that I have had one fail in my car that went high enough to blow out the very expensive 1977 headlights!!
    They were finally "bright", for about 12 seconds...LOL!

    Pull the unit and send it back to the rebuilder, or check that particular component if you rebuilt it yourself.

    Charging amps should be the 14.1A range you read in a normal situation.
     
  3. BigTex

    BigTex Seven Time F1 World Champ
    Owner Rossa Subscribed

    Dec 6, 2002
    79,143
    Houston, Texas
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    Bubba
    I really rely on an "old school" alternator starter shop......

    Not only are they usually more economical than a Parts Store rebuilt unit, I have had instances where I went thru two or three "rebuilt" alternators, to find one that worked!!

    The Tech changing them pointed out bearings out of alignment, pressed in too far, bench defects that undid the function of the unit.

    Luckily there was a topless bar, next to the Shop working on my wife's car!!!
    The only upside to the whole affair!
     
  4. rugby

    rugby Formula Junior

    Apr 10, 2015
    364
    Atlanta
    Not sure about the TR, but my 360 has a battery voltage sense cable going into the alternator. If that connection is intermittent, it might produce the symptoms you have.
     
    cobretti likes this.
  5. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    33,736
    Austin TX
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    Brian Crall
    No question there is an alternator problem but I can't see how it could be causing the running problem.

    Fix the alternator then diagnose the running issue.
     
  6. godabitibi

    godabitibi F1 Veteran
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    Jan 11, 2012
    6,252
    Papineauville, Quebec
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    Claude Laforest
    I don't really know how the alt is wired but it can also be a voltage drop to the regulator. For the regulator to do his job he need to READ the voltage. If the wire that serve to send the signal to the regulator has a bad connection or corroded connector or wire it will steal voltage(voltage drop). The reg now read a low voltage and try to move it up until it read it correct but it's output is higher than his reading and that is what your reading at the battery.

    That is exactly what Rugby is saying.
     
  7. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,039
    30°30'40" N 97°35'41" W (Texas)
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    Steve Magnusson
    (On late euro F113B or US F113A040 TR) The protection relay is designed to "protect" the KE-Jet electronics from the alternator going bonkers (by intentionally blowing its 10A fuse - and when that happens the system runs way lean because there is no current to the EHAs). As Brian said -- you'll need to fix the alternator (again) before doing anything else (but if you are lucky, it will just be that the protection relay fuse is blown causing the poor runability).
     
  8. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
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    Have you seen that fuse blow...ever? Just curious, I know it is there for that but have yet see it protect anything.

    You are correct though. It can cause a similar symptom if the relay stops and is worthwhile checking.
     
  9. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Jan 11, 2001
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    30°30'40" N 97°35'41" W (Texas)
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    Steve Magnusson
    The only report of that that I can recall is where someone had a part break off inside the protection relay and the fuse blew ;). No argument from me that the protection relay itself seems to cause way more trouble than it ever prevents, but the OP has measured the one condition (high alternator voltage) where the protection relay might actually do something useful -- maybe it will be a first....
     
  10. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
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    Austin TX
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    We shall see.

    For what it is worth I see them fail far more frequently on the 8cyl cars than the 12's for some reason. Very rare problem on a TR. There had to be something better on the TR over the 328.
     
  11. vincenzo

    vincenzo F1 Rookie

    Nov 2, 2003
    3,373
    GM parts perhaps!?!

    Life Is Good!
    Vincenzo
     
  12. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
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    No. Different vendors. All in the Fatherland.
     
  13. vincenzo

    vincenzo F1 Rookie

    Nov 2, 2003
    3,373
    #13 vincenzo, Mar 8, 2016
    Last edited by a moderator: Sep 7, 2017
    Hmmmm...

    Presumably you refer to the relay(?)

    This is the Alt out of my 1990 TR:

    Rgds,
    Vincenzo
    Image Unavailable, Please Login
     
  14. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
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    I thought we were talking about a relay in the FI system.
     
  15. chabch

    chabch Formula 3

    Aug 15, 2010
    1,075
    France
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    Christophe
    Thanks everyone! Quite a few things to check. I'll start by checking the alternator regulator connector making sure all is fine there, and I'll check the fuse on the protection relay. I'll keep you posted tomorrow!
     
  16. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    33,736
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    #16 Rifledriver, Mar 9, 2016
    Last edited: Mar 9, 2016
    Whatever the running problem is, the charging system needs to be fixed first. Keep your eye on the ball otherwise you might wind up chasing ghosts.
     
  17. rugby

    rugby Formula Junior

    Apr 10, 2015
    364
    Atlanta
    I would also check the other end of the voltage sense wire connected on the battery end. The wire is on the positive battery terminal and is the smaller of the two red wires (unless you have other accessories connected there too). Take that wire off and scrape the contact lug clean. Also make sure the wire is firmly attached to the contact lug by pulling on it.

    There should also be a fuse near that battery connection, perhaps in-line with the sense wire. I would change that fuse just in case the contacts are tarnished.

    And lastly I would do a continuity check with an ohmmeter between the battery sense wire contact lug (while it's off the battery) and the plug end at the alternator.
     
  18. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
    8,866
    southwest germany and thailand
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    romano schwabel
    remove again the alternator and send it to the shop you got it from. it is a regulator problem, nothing else.
     
  19. rugby

    rugby Formula Junior

    Apr 10, 2015
    364
    Atlanta
    Agree. No sense checking the simple stuff first when you can just replace more expensive things. It's more satisfying.
     
  20. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
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    Well that might be true but the wiring and fuse you suggest checking does not exist on a TR. The 12v wire branches off the alt output wire right at the alternator output stud. The only other wire goes to the charging bulb in the dash and interrupting that wire results in zero charging, not over charging. In a TR if it is over charging, it's an alternator problem.
     
  21. godabitibi

    godabitibi F1 Veteran
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    Jan 11, 2012
    6,252
    Papineauville, Quebec
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    Claude Laforest
    You're right I just realize the TR has a Delco alternator and the regulator read it's signal from the inner stud. The problem is from the internal of the alt.
     
  22. chabch

    chabch Formula 3

    Aug 15, 2010
    1,075
    France
    Full Name:
    Christophe
    #22 chabch, Mar 11, 2016
    Last edited by a moderator: Sep 7, 2017
    Hi everyone, a little update.

    I looked at the TR wiring diagram (see picture) and noticed that the input to the alternator's voltage regulator (108) is not internal to the alternator, but it's actually an external wire (1R) looping back that you plug on it. I was wondering what it was when I plugged it, but it's logical. I unplugged it and cleaned the connector in case the feedback loop would be faulty. I started the car and monitored the battery voltage for 20 minutes and not once did it go nuts. It was a nice steady 14v-ish. I'm hoping that's what it was as for the 19v craziness!

    But the engine is still stumbling and running poorly. I suspect when the voltage when nuts, it might have damaged something somewhere.

    Since I have stable voltage now (well for now), I want to start chasing down the stumbling/backfiring problem.

    Following your suggestions, I pulled out the box containing the protection relay with the 10A fuse. By the way, getting this box out through the cables and frame is a serious puzzle... I reached the relay, and the fuse is fine. While I was in there I tested the relay and it's working fine. I cleaned all connectors and put everything back together. I checked the car was running the same way (let's not accumulate issues), and that's where I am right now.

    What should I do next? :)
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  23. rpissm

    rpissm Formula 3

    Aug 11, 2013
    1,620
    Salt Lake City, UT
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    Joe
    Is it backfiring just when cold, or after it has warmed up too? And when does the backfire happen? On deceleration or idle?
     
  24. chabch

    chabch Formula 3

    Aug 15, 2010
    1,075
    France
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    Christophe
    Hi Joe, it's backfiring a little when at idle (warm or not) and the revs drop slowly more and more as it stumbles. It never stalls but it backfires when under 600rpm.

    It does not backfire if I hold it at 900rpm or above.
     
  25. rpissm

    rpissm Formula 3

    Aug 11, 2013
    1,620
    Salt Lake City, UT
    Full Name:
    Joe
    My tr will backfire on deceleration when cold. I need to drive it around the block when cold before I slam the gas. I'd say there's something up with your idle circuit in your fuel distros. Have you run some injector cleaner through lately? Maybe you have some crap in there. How about the fuel filters too? When was the last time you changed them?
     

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