 Help :) 75 2.0/FI runs perfectly until the car is warm and under electrical load, Advice? |
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| Jett |
 Feb 16 2022, 05:34 PM
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#1
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Senior Member  Group: Members Posts: 1,642 Joined: 27-July 14 From: Seattle Member No.: 17,686 Region Association: Pacific Northwest 
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Our 75 2.0/FI car has completed a two year restoration that included an engine and transmission rebuild, along with rebuilding or replacing all FI components.
The car runs perfectly all the time until it has been running with electrical load for 30 min (radio w/Bluetooth, rear fan) and then I turn on the headlights. The car immediately starts to sputter and will die unless the lights are turned off, which puts the car back to perfect. We initially thought that it was a bad ground in the headlight circuit, but cleaned and verified, no red flags there. Is it possible that the mounting plate for the regulator has a bad connection? I think it is original to the car. Any help would be greatly appreciated as last week I had no lights coming back from the first cruise. Thanks |
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Replies(1 - 7)
| Van B |
Feb 16 2022, 05:59 PM
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#2
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Senior Member Group: Members Posts: 1,613 Joined: 20-October 21 From: Maryland Member No.: 26,011 Region Association: None
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Have you measured voltage under these different load conditions?
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| emerygt350 |
Feb 16 2022, 06:09 PM
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#3
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Advanced Member Group: Members Posts: 2,154 Joined: 20-July 21 From: Upstate, NY Member No.: 25,740 Region Association: North East States |
Yeah, what van said. I would suspect the regulator just due to recent issues with the old buggers (used and nos) not ever being able to kick good voltage to the battery.
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| emerygt350 |
Feb 16 2022, 06:15 PM
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#4
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Advanced Member Group: Members Posts: 2,154 Joined: 20-July 21 From: Upstate, NY Member No.: 25,740 Region Association: North East States |
I would also point towards some strange ground issue at the rear. I had quite a bit of luck checking resistance to ground from various points on the motor in my search for low charging issues. Fan shroud to ground, starter, etc.
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| Superhawk996 |
Feb 16 2022, 06:58 PM
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#5
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914 Guru Group: Members Posts: 5,916 Joined: 25-August 18 From: Woods of N. Idaho Member No.: 22,428 Region Association: Galt's Gulch
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QUOTE(Van B @ Feb 16 2022, 06:59 PM)  Have you measured voltage under these different load conditions? (IMG:style_emoticons/default/agree.gif) Start with the basics as suggested above. The headlamps are the largest electrical load on a stock 914. Sounds like you're getting low battery voltage and when you apply the large headlamp load it collapses the battery voltage. Probably to the point that the coil or the ECU no longer have adequate voltage supply causing the mis-fire. Quickest fix will be testing with DMM in a methodical manner. |
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| Jett |
Feb 16 2022, 08:07 PM
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#6
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Senior Member Group: Members Posts: 1,642 Joined: 27-July 14 From: Seattle Member No.: 17,686 Region Association: Pacific Northwest
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Thanks for all the feedback! Will report back.
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| rhodyguy |
Feb 16 2022, 08:16 PM
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#7
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Chimp Sanctuary NW. Check it out. Group: Members Posts: 22,098 Joined: 2-March 03 From: Orion's Bell. The BELL! Member No.: 378 Region Association: Galt's Gulch |
What happens when you turn off the aux fan? Is the idle low when everthing except for the lights are turned off? Does the gen/alt light flicker?
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| Jett |
Feb 17 2022, 08:46 AM
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#8
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Senior Member Group: Members Posts: 1,642 Joined: 27-July 14 From: Seattle Member No.: 17,686 Region Association: Pacific Northwest
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QUOTE(rhodyguy @ Feb 16 2022, 06:16 PM) What happens when you turn off the aux fan? Is the idle low when everthing except for the lights are turned off? Does the gen/alt light flicker? Nothing noticeable and no Gen light. |
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