2010 GT500 charging at 15.4v.

[onecrazydog]

My Buddy has a slow Silver 2010 GT500... It charges at 15.4 volts... We put a heavy duty alternator in it awhile ago, but no change to the charging... He had the factory alt tested and it was good... New battery too...

So, could this be an ECU thing or a setting in the tune? Car runs great...

[68fastback]

It can be set in the tune. Ford seems to sets it to around 14.2-14.6 volts ...15.4 seems an odd voltage.
If his engine has mods such that he's shy on pump capacity, a higher voltage is sometimes used (by some tuners) to tweak stock capacity bit or more (little black box) but that usually uses around 17v (? as I recall) -- bad idea, imo vs more native pump capacity. It also shortens the life of the alternator.

[Alloy Dave]

I'd suspect the tool he's measuring with as being out of calibration...try testing yours and see what you get.

[Tommy Gun]

Yeah, stick your tool on it.

[onecrazydog]

It can be set in the tune. Ford seems to sets it to around 14.2-14.6 volts ...15.4 seems an odd voltage.
If his engine has mods such that he's shy on pump capacity, a higher voltage is sometimes used (by some tuners) to tweak stock capacity bit or more (little black box) but that usually uses around 17v (? as I recall) -- bad idea, imo vs more native pump capacity. It also shortens the life of the alternator.

Is there a way to check to see what the voltage is set at in the tune? Reg mods, TVS, pulley... Tune was thru Joe, so not sure if it was a Jim tune or Tasca tune? Joe?

[onecrazydog]

I'd suspect the tool he's measuring with as being out of calibration...try testing yours and see what you get.

It's been tested with different tools, all say the same thing!!

[onecrazydog]

Yeah, stick your tool on it.


:umno:

[Tommy Gun]

:look:

[68fastback]

Is there a way to check to see what the voltage is set at in the tune? Reg mods, TVS, pulley... Tune was thru Joe, so not sure if it was a Jim tune or Tasca tune? Joe?

I don't think Jim or Tasca would mess with the voltage so maybe it is a measurement problem like Dave mentioned.

It can certainly be checked because it can be set in the tune, but I don't now if that setting can be easily checked -- i.e. without tuning software.

DC and AC do measure differently (meters have selections for both AC and DC volts) and I'm not sure which would be correct (because there is the imperfect charging waveform superimposed on the dead-flat DC of the battery) but I've always used the DC volts setting to measure on the assumption that the alternator's rectification is fairly smooth (which it may or may not be).

[Tommy Gun]

Are you trying to tell OCD how to use a voltmeter? :giggle:

[Boston Mike]

Is there a way to check to see what the voltage is set at in the tune? Reg mods, TVS, pulley... Tune was thru Joe, so not sure if it was a Jim tune or Tasca tune? Joe?

There's your issue.

:haha:

[68fastback]

Are you trying to tell OCD how to use a voltmeter? :giggle:

:nonono: :lol:

[onecrazydog]

It might have been this way right from the factory... Can we load the factory tune, start the car and let it idle to check the voltage? Will it even start with mods, tvs and throttle body? Like I said, car runs great, no issues, we are just trying to figure out why the 15.4 charging rate... Not sure if that could damage any electronics like the stereo over time?

[onecrazydog]

There's your issue.

:haha:

Lol...

Joe was always awesome to deal with!!

[68fastback]

It might have been this way right from the factory... Can we load the factory tune, start the car and let it idle to check the voltage? Will it even start with mods, tvs and throttle body? Like I said, car runs great, no issues, we are just trying to figure out why the 15.4 charging rate... Not sure if that could damage any electronics like the stereo over time?

I don't see a problem loading the stock tune and just running at idle to check voltage ...assuming MAF meter is still stock (probably is) and tune hasn't rescaled it to double it's range (under 700HP probably hasn't) it should start and idle ok. Even the bigger TB should not be an issue (as long as not driving it). It might set a wrench-light if you blip it but probably not b/c it's not under any load. Just my best guesses.

[onecrazydog]

I don't see a problem loading the stock tune and just running at idle to check voltage ...assuming MAF meter is still stock (probably is) and tune hasn't rescaled it to double it's range (under 700HP probably hasn't) it should start and idle ok. Even the bigger TB should not be an issue (as long as not driving it). It might set a wrench-light if you blip it but probably not b/c it's not under any load. Just my best guesses.

Yes it still has the factory maf with I think a JLT cai... TB is an L&M 66, Ford Racing TVS, 2.6 pulley, the 123 cai, I think that is it for power mods... So around 620 hp I think... I can't remember if it has headers or not...

We would just start it and check the voltage at idle then shut the car off... The 15.4 doesn't fluctuate at all, load or no load...

We are also going to hook my scanner up to it for testing...

He was having problems like me with a dyno tune he had on his car... Then Joe hooked him up with this tune and it has been flawless, same as mine!! I remember when George hooked me up directly with Car Star Jim, that was awesome!!

[onecrazydog]

Thanks for all the ideas Dan, I was hoping you would do that!!

[68fastback]

:tiphat2: ...will be interesting to see if it's the same.

[onecrazydog]

We did some testing and figured it's a loose cable or the PCM... We unplugged the alternator and the charging dropped to 13.9, so the alternator is good...

He took it in to his mechanic and they did some testing and figured it was the PCM... So they have to order a new one, I wonder what they are worth? At least we know the problem now... It was driving my Bud crazy!! Lol!!

[Alloy Dave]

Wow...glad you figured it out. That would have been tough to diagnose for me. No idea what one costs though.

Now get back to working on that house :fryingpan::fryingpan:

[onecrazydog]

Now get back to working on that house :fryingpan::fryingpan:


That's the plan!!

[Tommy Gun]

PCMs on anything can be crazy expensive. :(

[Tommy Gun]

Wonder if a reflash would change this before going to replacement?

[68fastback]

Wonder if a reflash would change this before going to replacement?

+1 ...worth a try.

It also seems odd that it dropped to 13.9 with the alternator disconnected ...should drop to 13.2 pretty quickly (15 minutes or so -uncertain) and then 12.x after sitting overnight with no parasitic drain (i.e. battery physically disconnected). If it dropped to 13.9 immediately after shutting it off, I guess that's understandable if it was being charged at 15.4 by the alternator, but it should come down pretty quickly after shut off/disconnected.

[onecrazydog]

We unplugged the input to the alternator and tested it while the car was running... Without the car telling it what to do the alt put out 13. something... As soon as you plug the input back in it jumps to 15.4...

[68fastback]

Ah, well ...it's not that far off. Fords I've had usually drive alternator to provide about 14.5 charging volts +/- 0.3 ...15.3 is a bit high, though. I'm not familiar with what GT500 factory ECM load commands.

[onecrazydog]

Wonder if a reflash would change this before going to replacement?

Mechanic tried that... This guy is supposed to be really good at electrical stuff, and can do all the re flashing... They are also going to clean up some stereo and accessory wiring going to the battery... They figure a couple grand for everything including the pcm and labor...

He can afford it!!

[68fastback]

That should do the trick!

[Tommy Gun]

Couple grand? :faint:

[onecrazydog]

Couple grand? :faint:

Labor up here is always expensive...

[Tommy Gun]

Probably have to make money while you’re not snowed in for 9 and a half months :giggle:

[onecrazydog]

He ended up sending his pcm to Ford instead of buying a new one... Good thing, it's not the pcm... Everything is fine until the 91 or 93 tune get installed, charging then jumps up past 15v...

It's the tunes...

[68fastback]

Glad they found it!

Aftermarket tunes have been known to cook alternators. But why do they do it? Possibly it has to do with pump pressure recovery or fuel delivery when tune is pushing close to pump limits ...something like that.

[onecrazydog]

He is going to call Tasca, that is where the tune is from...

[Tommy Gun]

Wow, never heard of this before.

[68fastback]

Dennis Gomes really knows his stuff, so will be interesting to understand...

[onecrazydog]

He ended up going with a new tune from BJ who used to work at VMP... He has his own tuning company now... I helped my Bud load the tune, then we did some data logging(something new I learned how to do), BJ did some tweaks and car is running and charging normal!! I think the tune is a bit more conservative than the tasca tune but that's ok with my Bud... He also swapped out his L&M 72 TB to the Ford Racing TB...

Speaking of Throttle bodies, I never did get mine back from G Force... That sucks...

[Tommy Gun]

BJ is cool, met him in Vegas last year.

He had his Focus RS in the Ford booth...what a privilege!


Sucks about your TB :(

[68fastback]

He ended up going with a new tune from BJ who used to work at VMP... He has his own tuning company now... I helped my Bud load the tune, then we did some data logging(something new I learned how to do), BJ did some tweaks and car is running and charging normal!! I think the tune is a bit more conservative than the tasca tune but that's ok with my Bud... He also swapped out his L&M 72 TB to the Ford Racing TB...

Speaking of Throttle bodies, I never did get mine back from G Force... That sucks...

Hmmm ...some flow reduction but otherwise a decent TB.

[onecrazydog]

Hmmm ...some flow reduction but otherwise a decent TB.

I haven't had any issues with mine... I wonder if I can put the 72 on my car without any tuning change... Have to ask Jim!!

[68fastback]

I haven't had any issues with mine... I wonder if I can put the 72 on my car without any tuning change... Have to ask Jim!!

Probably can ...you probably have a more MAF and pump capacity so no prob there. Yeah, check w/Jim. There's a simple adjustment on the TB -- you can check with your VOM meter and, if necessary, adjust. I forget the procedure but it was taking Jim and George just a few minutes check/adjust once the TB was mounted.

[onecrazydog]

BJ is cool, met him in Vegas last year.

He had his Focus RS in the Ford booth...what a privilege!


Sucks about your TB :(

BJ is cool, I met him at Shelbyfest!! He was great to work with while setting the tune in my buddies car!! He did a phone session with us, and helped with the data logging!! It is a bit more conservative from the Tasca tune but my Bud is happy with it... Car runs awesome, charging is down to normal, success!!

The TB scenario does suck, oh well... When I rebuild my transmission I wont be calling them...