94 GT Overcharging

RichV

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Had a situation with my race car overcharging for about 15min. I heard a pop on track, didn't think too much about it at the time. When I came back into the pits I noticed liquid near my battery box. Sure enough the battery cell covers have both popped off. I cleaned and filled with some distilled water, put the covers back on. Next session the alternator stopped charging, failed completely.

No big deal, got a new alternator. However at the next track day, the car was severely lacking power. Probably 30-40hp would be my guess. Comparing data from past sessions, my laptimes went up by almost 8sec (2:08 to 2:16) and comparing speeds at the end of long straights is off significantly. So I figured that maybe I had something going on with the top end. Tore it apart, didn't find anything but replaced the ignition tune-up parts anyway.

Back at the race track this last weekend, no improvement!! Last race of the season, but still frustrating running int he back of the pack.

So now I'm going back to the alternator incident, thinking what could have fried. Seems to run fine, stock 94 Cobra tune, stock MAF/injectors, sensors. All seem to be reading the right #s (through moates QH). Any thoughts?

I have a spare MAF, distributor, coil, and a line on a ECU. So thinking just pull the trigger on a parts shotgun and replace all that stuff since it's easy.
 

ttocs

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Any idea what the rpms were on the car? I have heard of people having issues from overspinning it for too long during races and causing problems. They fixed it with underdrive pullies to slow it down.
 

RichV

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I run the U/D pulleys since there really isn't any electrical demand. No HVAC, lights, radio, etc. Just a few AutoMeter gauges and a data system. But this is the first alternator that has puked since I built the car in 2011-12.

I'm just thinking what could have fried that could be responsible for the power loss. Wiring diagrams have the potential 20v going to pretty much all the components, looks like the ECU outputs sink neutral/gnd so anything from fuel injectors to the ingnition components got the 20v. Just not sure what's most sensitive to that kind of a spike.
 

ttocs

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if the alternator lasted for 10 years I don't think its necessarily anything you did wrong.
 

RichV

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Agreed. Just think it was a normal failure. But it took something with it for sure.
 

95opal

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Had a situation with my race car overcharging for about 15min. I heard a pop on track, didn't think too much about it at the time. When I came back into the pits I noticed liquid near my battery box. Sure enough the battery cell covers have both popped off. I cleaned and filled with some distilled water, put the covers back on. Next session the alternator stopped charging, failed completely.

No big deal, got a new alternator. However at the next track day, the car was severely lacking power. Probably 30-40hp would be my guess. Comparing data from past sessions, my laptimes went up by almost 8sec (2:08 to 2:16) and comparing speeds at the end of long straights is off significantly. So I figured that maybe I had something going on with the top end. Tore it apart, didn't find anything but replaced the ignition tune-up parts anyway.

Back at the race track this last weekend, no improvement!! Last race of the season, but still frustrating running int he back of the pack.

So now I'm going back to the alternator incident, thinking what could have fried. Seems to run fine, stock 94 Cobra tune, stock MAF/injectors, sensors. All seem to be reading the right #s (through moates QH). Any thoughts?

I have a spare MAF, distributor, coil, and a line on a ECU. So thinking just pull the trigger on a parts shotgun and replace all that stuff since it's easy.
What do the plugs look like?
 

tvsn95

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SOOO you have a quarterhorse what are the bat voltage data logs showing ????
 

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