WOT Voltage drop

[TT/Ameasap]

Haven't had a chance to play with it yet. Been real busy lately. Should get to it this week If I don't get sick... Family is down with a nasty littl bug.

 

[TurboBuRick]

Keep in mind higher amp alternators will not solve low voltage problems when wiring is the issue. The other draw back of higher amp alternators, they take more rpm before they make power. At idle they don't make power and if you don't upgrade the wiring, it's useless.

Best bet is to take the aftermarket load off the factory fuse panel and run separate power feed inside the car to a relay and use that to power accessories. System voltage will then increase.

Rick

 

[Sweet6]

Keep in mind higher amp alternators will not solve low voltage problems when wiring is the issue. The other draw back of higher amp alternators, they take more rpm before they make power. At idle they don't make power and if you don't upgrade the wiring, it's useless.

Best bet is to take the aftermarket load off the factory fuse panel and run separate power feed inside the car to a relay and use that to power accessories. System voltage will then increase.

Rick

For whatever reason when I swapped to a 200 amp alternator and my volts went up slightly at WOT on my TTA. I used my stock GN alternator on my TTA and the volt difference between the cars was a full volt or maybe a little more. I might have picked up a half volt on my TTA when I put in a 200 AMP alt. But I agree there could be a wiring issue somewhere.

 

[RmvBfrFlght]

Another item that can help with system voltage is to use a smaller diameter pulley on the alternator. I don't recommend it for higher RPM engines. But on engines that get shifted by 5000 RPM (or so) it is helpful. Spins the alternator faster.

RemoveBeforeFlight

 

[TT/Ameasap]

I'm spinning 6k RPM.

 

[TT/Ameasap]

Swapped belts and nothing changed. Still @12.2-12.5 volts couple frames dropped to 12.0
This was about an 1/8 mile run at 19-20psi boost and alky half way.
Im gonna do the alt. test next.

 

[TT/Ameasap]

Also noticed if I turn everything on like, lights,radio,HS fan, and it will read 13.0- 13.2 at idle
When its normally 13.8-13.9 at idle

 

[87geeinn]

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.

NO, NO, and NO. You should NEVER put a higher rated fuse in. The belt is not your problem. A 200 amp alternator is a bad idea and will probably not last you a year before it burns up.

Keep in mind that the numbers you are reading from the Scanmaster are what the ECM is seeing and where the voltage is being read from. Hell, engine off I have 12.0v showing on Scanmaster when a voltmeter directly on the battery/back of the alternator stud reads 12.6 (fully charged, healthy battery). You are definitely going to have some offset there. I think you have a wiring issue...possibly old wiring that can't handle the amperage, hence the fuse blowing. A fuse blowing is a very good indicator that there is a wiring issue. Putting a higher rated fuse in there will only delay the fuse from blowing again in the future...which is bad. Fuses keep your car from going up in flames when something goes awry in the electrical system.

Also, you said you had a "new" alternator from Autozone. Bad idea there too. At minimum, go to NAPA and get one of their higher end, 120 amp units. An alternator will show it's ass at higher RPMs when the demand is highest.

 

[87geeinn]

Also noticed if I turn everything on like, lights,radio,HS fan, and it will read 13.0- 13.2 at idle
When its normally 13.8-13.9 at idle

When are you taking these readings? The voltage will drop as a cold engine warms up. I often seen 14v+ on startup and end up around ~13.2 average when the engine is fully warmed up.

 

[TT/Ameasap]

I think I found the problem. Not sure. But this is what I found. The previous owner installed a boost commander and wired it to the ECM . I decided to take it out because I never use it and I was already installing a new PLX wideband. He had just twisted the wires loosely on those aligater/scissor connectors for each wire.. Tps, boost,power,ground,ect. I pulled each wire off and inspected each wire.. I then taped the wires individually from being exposed. I will get a log today.

 

[TT/Ameasap]

Alky on 6-7 (3/4) logged a run deep into 3rd gear. Volts were 12.5-12.7 AFR is 10.8-11.0 no kr on 20psi
Problem not solved but a little better.

 

[TT/Ameasap]

Running E85 and no alky. Now im at 13.3-13.4

 

[Sweet6]

Running E85 and no alky. Now im at 13.3-13.4

Iam not surprised. I think the TTAs have ground issues. Or some other gremlin.

 

[Razor]

Running E85 and no alky. Now im at 13.3-13.4

With lights on or off?

Run it with lights on and see if voltage is low, if so.. then you have a weak alternator. The alky kit draws ~10 amps. If a meesly 10 amps makes your system drop a volt.. time for a bigger/new alternator

 

[Sweet6]

I had the same issue in my TTA. My TTA had 12.0 volts at WOT with the alky. So I switched over the alternator from my GN that I was getting 13plus volts at WOT with the alky. And the TTA still showed 12.0 volts. I did put in a 200 AMP alternator and it got a little better.

 

[dandaman]

3amp 50V diode in the sense wire will bump voltage around .4 volts. If more is desired add 2 diodes in series for around .8 - 1.0 volt. Less than 50 cents from most electronics outlets.