The alternator replacement thread, Fixed! |
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The alternator replacement thread, Fixed! |
VaccaRabite |
Aug 12 2018, 07:07 PM
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#1
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En Garde! Group: Admin Posts: 13,444 Joined: 15-December 03 From: Dallastown, PA Member No.: 1,435 Region Association: MidAtlantic Region |
Waiting on the side of the road for a flatbed to take me home.
Engine ran great. Charging system not so much. Driving along. Lights started going dim. Car started bucking. Only 5 miles to home but it wasn’t going to make it, and no shoulders to pull over safe on the little farm roads. So I pulled into a spot I knew of and shut it down and parked it and now I wait. McMark had said earlier he wasn’t sure about the charging system. But the alt light was not on and no issues before now. So. What’s the alternator I need to buy? Maybe a new VR as well? I guess I should test the battery and make sure it’s okay too. Zach |
VaccaRabite |
Sep 7 2018, 02:14 PM
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#2
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En Garde! Group: Admin Posts: 13,444 Joined: 15-December 03 From: Dallastown, PA Member No.: 1,435 Region Association: MidAtlantic Region |
I got a new battery.
Not really any change over the smaller race battery. So I started playing with the collection of VRs I have recently collected. Depending on what VR I used, at idle I was seeing a range from 12.3 volts to 13.6 volts. The best results were from a hella solid state VR and an unamed adjustable solid state VR. With headlights and driving lights on, I’m showing 12.5 at the battery with the better VRs at hot idle. The voltage still drops when the engine revs, and sits at about 12.3-12.5 volts at 4K. If I short DF and D+ voltage DOES rise with rpms, and quickly goes up to 17-18volts. I have gone through all my grounds and currently see 0.000 ohms resistance anywhere. No resistance between engine case and negative battery terminal. None between alternator and engine or alt and body. My measurements from the battery and the voltmeter on the ECU are different by a volt (ECU sees slightly less voltage then the battery is showing). I’m left thinking this is just how my car is, and I DO NOT like it. I’m totally stumped, and have run out of things to replace. I think my car is probably fine to drive during the day, but I am afraid to drive it anywhere at night. Help? @spoke @clayperrine @mcmark PS. I just reread Spoke’s last post and still need to measure voltage between D- and the body. I’ll do that tonight. Now I’m off to the hospital to give comfort to mom. Zach |
Spoke |
Sep 7 2018, 09:50 PM
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#3
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Jerry Group: Members Posts: 6,978 Joined: 29-October 04 From: Allentown, PA Member No.: 3,031 Region Association: None |
I got a new battery. Not really any change over the smaller race battery. So I started playing with the collection of VRs I have recently collected. Depending on what VR I used, at idle I was seeing a range from 12.3 volts to 13.6 volts. The best results were from a hella solid state VR and an unamed adjustable solid state VR. With headlights and driving lights on, I’m showing 12.5 at the battery with the better VRs at hot idle. The voltage still drops when the engine revs, and sits at about 12.3-12.5 volts at 4K. If I short DF and D+ voltage DOES rise with rpms, and quickly goes up to 17-18volts. I have gone through all my grounds and currently see 0.000 ohms resistance anywhere. No resistance between engine case and negative battery terminal. None between alternator and engine or alt and body. My measurements from the battery and the voltmeter on the ECU are different by a volt (ECU sees slightly less voltage then the battery is showing). I’m left thinking this is just how my car is, and I DO NOT like it. I’m totally stumped, and have run out of things to replace. I think my car is probably fine to drive during the day, but I am afraid to drive it anywhere at night. Help? @spoke @clayperrine @mcmark PS. I just reread Spoke’s last post and still need to measure voltage between D- and the body. I’ll do that tonight. Now I’m off to the hospital to give comfort to mom. Zach About the voltage measurement from D- to chassis, connect the negative lead to the chassis post beside the relay board. You should read 0.0V since the alternator case is bolted to the fan shroud which is bolted to the engine case which is bolted to the transmission which is strapped to the chassis post under the trunk. All should be 0.0 ohm connections. The strap does have finite resistance which is proportional to its length; maybe 10 mOhm. A loss of even 1V with the ground will greatly affect the charging circuit. I doubt this is an issue but we've got to cross off all variables. With the charging problems you've been having, something in the charging system is definitely wrong. You haven't found it yet. It shouldn't be the battery, alternator, or VR since you've changed all these items and the system still isn't right. Which VR gave 13.6V at idle? Seems that VR is the best candidate seeing that you can get high voltages when DF is shorted to D+. With DF shorted to D+, do you see the same drooping of voltage when revving the engine? Which VR gave the drooping voltage you quoted? |
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