Voltage problem
 

OK so I tired to get tuned and it was a failure. They say my voltage is to low and causing ignition missfires under boost.

When you start the car it's around the 14 volt range but drops quickly to 12.5 volts. It stays at 12.5 volts and don't move even if you turn the air or headlights on.

I'm running a 25% underdrive pulley but other than that the charging system has been untouched.

Any ideas?
At low rpm the car also will stumble without being in boost.

Could the internal voltage regulator in the alternator be on its way out?(I think it's internal these days.)

Try adding more grounds and cleaning all the others...go from there...good luck...

I would get rid of the underdrive pulley. Even though its not likely your problem, you literally are going to be in the 800 to 1000 range i don't see a need for it. I also thought that our cars regulate voltage to around 12.5 after the car has ran awhile. No matter what accessories are on it keeps it in that range. Sounds like something else is up or you need a new tuner.

^^^

Our cars do manage the voltage...

-Don

Whats the idle? with the high lift of our cams I use on this cam and my last a 950 idle rpm, and the deal is the internal voltage regulator on the alternator should kick to get more out, I do though use a nice Fluidampr which only under drives the alternator which at higher rpm idling causing net no loss in power and BTW under drive pulleys usually are a cheap add on for most which in our internally fairly well balanced stock engine is not needed with just a stupid non harmonic balancer pulley..basically a weight that is a pulley.

Old school harmonic balancers are a lot like the cheaper versions of the under drives on the market for our engine..over time I have on here seen the SLP cheaper stock like under drives fail just like the stock, they have a cushion of rubber between two metal surfaces that is supposed to help eliminate harmful vibrations.... kind of like the stock non balancer.... Old motor heads like me know investing in a radical build usually meant smart money on a real expensive engine was to spend the money on a Fluidampr with a viscous silicone fluid inside or a ATI both of which cost $400 up not a 200$ TSP or cheap pulley basically not saving the engines bearings or cam or anything from vibrations.

With a old fairly high quality build on a SBC/BBC a stock harmonic balancer was usually fine because of balancing and the fact the cam may have been .500 lift built with durations making the performance a lot, and that's a aftermarket cam with flat tappets..our stock cam is in the .550 range and our lifts with our cams for aftermarket are unachieve-able with a flat tappet and would be considered insane lift for a street strip engine with it failing if ever attempted and requiring spring rates they would be very uncomfortable with....

Anyway with your build I would be running the Fluidampr with no underdrive pulley which they do make, now their quality is top notch and may not affect things, but at least you know you would have a real balancer saving the engine harm and it would not be a issue down the road if it falls apart form the rubber breaking between the metal rings . If you need higher voltage you may want to think aftermarket alternator also and talk to a auto electrical shop, My tuner Mr.Wong told me when I bought a TSP under drive it looked cheap and he did not want to use it and I agreed and sold it and went with better....And that's just with my experience on a N/A build over time.

Yes you should be able to see voltage change when driving to lower voltage to maintain its charge and not boil the battery, if you need more voltage due to the increased load on the system you may need a good electrician to look at it. I do not under drive the A/C as I like A/C especially if stuck in traffic, and claims of under drive pulleys are snake oil IMO and can free up little to make it worth the money spent IMO. Good Luck. I don't see in your list of mods better ignition components like the money for say some sultans of spark coils or other things that add up and also wonder if your running the right plugs most likely some NGK tr7ix.... I like to look to http://www.granatellimotorsports.com/ for their parts when it comes to electrical, and I do use their zero ohm wires though they may not be needed......

I would have to concur that the voltage, as reported by the DIC, doesn't seem abnormal in and of itself. The voltage regulator will drop charging down to 12.5-12.6 as soon as there isn't a need to charge at a higher rate. If you're battery is in good condition, and it seems like it is by the charging rate you describe, maybe the problem is elsewhere, under load of course.

On a side note, as a shade tree mechanic, experiences like yours are a double edged sword for me. I admire how you aren't bothered by engine failures, tearing into the motor, rebuilding and starting over, but you've seemed to have had nothing but oiling, fuel and electrical system issues since doing so....Hope you get it sorted out soon so you can enjoy your work!:pop2:

On a side note, as a shade tree mechanic, experiences like yours are a double edged sword for me. I admire how you aren't bothered by engine failures, tearing into the motor, rebuilding and starting over, but you've seemed to have had nothing but oiling, fuel and electrical system issues since doing so....Hope you get it sorted out soon so you can enjoy your work!:pop2:[/QUOTE]

And the cash flow too!:biggrin:

True dat!!

My voltage can reach 15.2 V for a short time. I heard that this can kill an AGM battery. Could you please advise whether it is possible to change the voltage regulator in the generator? If so, what is the part number?

The Max voltage can be changed in the ECM tune. You would need a tuner to do it or a platform like HP Tuners to do yourself. I believe 15 volts is the max for the stock tune. I do not know if it affects the AGM batteries.

Stock tune,sometimes you can see for a long time 15.2 V.

So it's normal 15.2 V ? :happy0180:

Yes up to 15.2 is normal. I just looked at a data log from my car and it peaks at 15.2 but usually spends most of it's time right at 15 and I do have a new battery as well. Also I see no way to change the output voltage of the alternator in HP Tuners.