WOT Voltage drop

T

TT/Ameasap

The White Blur
Joined
Jan 31, 2002
Car runs at 13.5 at idle. When tuning without alky my voltage is around 13.2 @WOT. Soon as I start adding alky the volts drop in the 12's @WOT. The more alky the more voltage drop I get. Last WOT run was as low as 12.2
I have PL logs if needed.
 
I had almost the same issue with an e-85 car we were tuning, as the RPM increased, the voltage decreased even with Casper's volt booster in place.

The alt was removed and checked and all values were proper, but I decided to put on a new alt and voltage was back at 14 volts at WOT. :)

I did ask John to see if he could make a volt booster to actuate before 70% throttle as many street cars, especially on e-85 and alky injection, need more fuel voltage at lower RPM?
 
your alternator voltage may not be dropping, you may be getting voltage drops in the wiring harness.

where are you getting power for the alky pump from? try using a different source to feed it.

also you could try measuring the alternator voltage at WOT (you would need to run some wiring into the car, and have a copilot measure while you drive)

Bob
 
Had the same problem, alt charged fine but at wot wasn't keeping up...got the alternator rebuilt bada bing all the voltage I need. This was with a volt booster now reading around 15 at the f.a.s.t.
 
The alt. is new from autozone. Im sure it would be in range for a normal car. I will recheck everything.
I do have some numbers from testing various places from that turbo 6 website tho. I'll post em up tomorrow.
 
I had bought an Impala 140 amp alternator still getting it but as Bob stated I changed the source by putting in an automotive relay to feed my alky pump and only drops to a minium of 12.2, 12.3. (usually 12.5 avg.) Before it was in the 11.8s!!
 
The voltage is read by the computer and its ignition circuit. Not at the back of the alternator. So you could have 2 volts off.

Now the alternator regulates voltage by sensing its output. So as the output goes down the regulator is supposed to keep the voltage at the same level. The word regulate means that. Like the thermostat in your house. You can set it to 60 doesnt mean your going to get 60 with the doors open on the house.

So a volt booster basically sets your alternator to "60" but if it cant keep up with the load.. then voltage is still going to drop.

Measure voltage on the back of the alternator when you make a run.. if its at 14.. dont worry about it. If it drops.. then new alternator/belt. Careful with the reman junk as its not rated properly.
 
TurboBuRick said:
Take as much aftermarket load off the fuse panel as you can. ;)
Click to expand...

Where else can I put the wires that need IGN. sources?
Weird thing happend today. I went WOT and the gauge fuse blew. The dash,scanmaster,alky,and aftermarket gauges all went out. There is nothing feeding into the gauge cluster fuse at all. But when I replaced it with a new fuse, all the gauges,alky,SM turned back on again.
 
Run a fused hot wire from the alt to a relay under the dash. Use ignition source to pull in the relay.
Feed accessories with switched power from the relay.
 
TT/Ameasap said:
Where else can I put the wires that need IGN. sources?
Weird thing happend today. I went WOT and the gauge fuse blew. The dash,scanmaster,alky,and aftermarket gauges all went out. There is nothing feeding into the gauge cluster fuse at all. But when I replaced it with a new fuse, all the gauges,alky,SM turned back on again.
Click to expand...

My TTA blew fuses too from the alky. Same fuse as you. The dash died. I just put in a little stronger fuse.

Happened to my buddy too. Seem to be common.

I did put in a 200 amp alt and my volts got better.
 
TurboBuRick said:
Run a fused hot wire from the alt to a relay under the dash. Use ignition source to pull in the relay.
Feed accessories with switched power from the relay.
Click to expand...

cool thanks!
Sweet6 said:
My TTA blew fuses too from the alky. Same fuse as you. The dash died. I just put in a little stronger fuse.

Happened to my buddy too. Seem to be common.

I did put in a 200 amp alt and my volts got better.
Click to expand...

Seems encouraging...I'll try a 15 amp fuse vs the 10 amp. I'll see what my volts are after getting that new belt on. If I have to go with a 200amp alt. then thats what I'll do.
 
I'm not going to say you need a relay powering everything but my alky kit definitely had one powering it and I had no problems with that fuse
 
I did some testing on an Alky pump, at 11.9 volts, full on, with a 15 GPH nozzle, the current was 5.2 amps. Not some thing that should be on the fuse box. I would imagine that with the voltage at 13.0, the current will be even higher.

RemoveBeforeFlight
 
Pump and system will draw over 10 amps
The pump at 200 psi draws 12 amps
Using the test button you'll see 4-5 amps
Hth
 
TT/Ameasap said:
cool thanks!


Seems encouraging...I'll try a 15 amp fuse vs the 10 amp. I'll see what my volts are after getting that new belt on. If I have to go with a 200amp alt. then thats what I'll do.
Click to expand...


Have you tried this yet?
I've got low voltage at WOT too.
 
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