Mechanical: Engine electrical master help wanted

[SuperShafts]

A few weeks ago i had a charging problem, 94 Jeep GC...the same one running like crap in the last spec drag i entered in exactly because of this charging problem...
This something with the charging system that has gone on since when the vehicle was bought new....it's a intermitent problem that would show up almost yearly like clock work...all of a sudden bang running off the batt, kill the batt jump start it....problem disapears, check everything , batt, alt, everything fine..WTH? ? :confused:

Another year goes by..and here we go again..and again, and again, and again...fast forward........................................... .................................................. .................................................. .................................................. .....
A month ago we thought we finally nipped the problem when it remained after having to be jumped and the alt wasn't charging...
Awesome get a new alt...and WTH while im at it lets go for more amps...

Damn we got a faulty alt....order another 1....hmmm 2 bad alts in the same day...i know my luck is sourly bad but...bench test it and it's charging...

Culprit can only be now at this point the comp. right?
The comp controls everything and including the charging system so if it isn't telling anything what's going on and the alt can't charge...well finally after all these years bingo...get a new comp...hurry up and order it and W A A I I T....
Well it gets here and pop it in and get ready to go racing tonight and low and behold....
Nothing...sob..stay up late last night, almost get arrested, get to wear crome bracelets squeezed on to me tight as can be as if i was a murderer on the lamb...for what and how and why im not sure of and can not believe what went on here...and all because of a quick 2 block road test and a k turn to return to the shop that is wide open and unattended... who knew making a k turn was suspicious activity and the officer throwing on the lights following a jeep to the shop 2 blocks up at 10 mph under the posted speed limit and pulling into a dead end garage left unattended and only proceding directly to the shop because of that would give anyone the impression im running from the law....aaaannnndddd i get off light with a few tickets as a consolation prize for not being arrested....awesome.....wth is going on in this world...anyway...

Charge the battery..ah no change the battery don't want to be puffing smoke and running like crap again....and well guess what here i am again...no power enough to run the motor pretty much anything off idle...and not to mention that now the idle is very eratic...but that might be a bad o2...

Anyone a master of electrical systems....

[art11758]

While I'm no master, I have an idea. I was under the hood of a 2003 Jeep and it had a Denso alternator with a hot and the two wire plug. The thing you are describing sounds like a regulator problem. The two wire plug if you have the same, says to me that it has an external regulator. The intermittent part sounds puzzling, although if you were able to wring out the field wire you might find high resistance which could be a crummy joint or a partially broken wire.

Anyways, my thought was why not just run a single wire alternator? I have used them in viritually everything and if there isn't one for your application,(like if it has a special casing or something) Anflo in Amityville used to make single wire setups for me pretty quick.

[SuperShafts]

Oh I absolutely understand the single wire alternator, I even run them so I can shut them off during runs, but none of them are in vehicles with mpi set up's and I don't know what problem may, if any, may arise if I go around the computer controlling the charging system.

I'll have to go thru the wiring schematic and see what might happen if I do it the other way.

[richardpetey]

Sorry, I just read this post and I think I can help................:help:
Some Jeep Grand Cherokees had a battery sensor built into the stock battery, when you replace the battery with an aftermarket battery (no sensor) most techs did not know what to do with the dangling sensor wire............................:eek:
If this wire is grounded or left open, the engine management computer (which controls your charging system) either full fields the alt. to overcharge the battery or does not allow the field to be excited and your entire electical system will run off your battery............:(
The fix is either get a stock battery sensor (not cost effective) or ground the wire through a resistor equal to that of the old sensor in the battery............................:cool:
UNCLE PETEY.....................:wave: :wave: :wave: :wave: :wave:

[SuperShafts]

Lol i was just gonna bring another battery with me....but i will look into that wire thank you very much sir