I have always found the statement that the alternator is "held back" from charging during cold start/ glow plug operation interesting.

So I made a video.

The alternator has 3 wires. The large charging cable to battery positive. The "A" wire is the sensing wire or the circuit that tells the voltage regulator how much output it needs. The "I" wire is the excite wire and tells the alternator to begin charging.

Left DMM is hooked to passenger + and - battery terminals. Right DMM is hooked to driver's side negative terminal and back-probed to the "I" wire on the alternator connector.

About 30 degrees outside, cold start and about 19 hour cold soak. 5W40 oil and the infamous "Buzz" flash for those curious.

<iframe width="420" height="315" src="http://www.youtube.com/embed/sTfun9Rzsuw" frameborder="0" allowfullscreen></iframe>

Interesting, huh? Alternator is commanded to begin charging immediately. I believe it comes down to the fact the alternator is just doing what it can during glowplug operation and once they time-out it can be finally charge as it should.

Josh

 

Video not workin 4 me.

 

I just purchased a AC/DC clamp meter that measures AC/DC amps and does volts and continuity and stuff like that and i put the clamp over the large charge wire coming from the back of the alternator and my alternator started charging from the moment the truck started, it was putting out 75 AMPS at very rough idle. I was gonna post a video but i didnt wanna run my truck again until i get the rough running condition fixed as i dont wanna damage anything while running with a bad injector. It makes sense though why the voltage acts the way it does until the glow plugs shut off as the glow plugs use 10 to 12 amps each and worst case they are using 96 amps so it would stand to reason that the battery voltage is pulled down until they shut off.

 

Might still be processing... works for me though.

Josh

 

The video worked for me. Josh, your truck sounds a little rough running for the first 5 or 10 seconds. Is it the truck or recording?

 

My truck sounds relatively the same way for the first 5-10 seconds on cold startup. I just attribute it to it being cold (30 degrees or less). Never heard a diesel that starts smooth on cold starts.

 

I attribute that to the "Buzz" flash. It's cold blooded compared to any of the other flashes.

Josh

 

I'm wondering if mine has the buzz flash as well. When I cycle the key on mine I can hear something that sounds like buzzing before I start it.

 

It cycles the injectors a long time before crank and then cycles up to 1 minute after engine shut-down.

Hence the nickname Buzz Flash. Many hate it, I happen to like it, but it does have some weird traits and being cold-blooded is one of them. You can pretty much forget running 15W40 under 40 degrees with the Buzz Flash.

My old 2005 also had that flash. Served me well for 150,000+ of the 170,000+ miles I put on that truck. Just couldn't use 15W40 from October to March

Josh

 

Yea, my truck had 15W-40 in it and during cold starts it ran like crap. Switched to 5W-40 T6 and Rev-X and it's MUCH smoother. I know the inductive heating was hit or miss, so I guess I'm not sure which the "best" flash is. From what I've read PHP has taken all of the good strategies and roll them into their tunes and threw the bad stuff out, so maybe that is the way to go.

 

Workin now.

 

Back to the original thread, my alternator absolutely is working as soon as the engine fires. My voltage goes from around 11 to 11.8 as soon as the engine fires.

As far as flashes are concerned, I have the latest flashes and my truck is starting perfectly at around 25 degrees. No buzz, no noise, just crank for 2 - 3 seconds at start, and then high idle automatically after about 2 minutes.

Brian

 

Yeah, the engine went to high idle right when I stopped recording.

The latest flash is impressive for cold starts... The horrible mpg is the killer.

Josh

 

I think it's time to go with a FICM repair from Ed and the Atlas 40 tune!

 

on the latest flashes, my mpg is acceptable to me, I can get 21 - 22 mpg unloaded and loaded with 9.5K on a very non-aerodynamic trailer over some serious hilly terrain I get around 11 - 12 mpg. It pulls astoundingly well, I am amazed every time I pull up another hill. I don't have any view of other flashes, but I am not unhappy.