Bad alternator?

james25 · Post by **james25** » Tue Jun 03, 2008 8:42 pm

Ive been having some weird charging system problems lately and I'm running out of ideas to solve it. Thought some of you guys could give me some inputs. I've checked and cleaned my grounds, the battery is fairly new, and the alternator seems to be ok according to the testings I did based on the helms manual. Here's my problem, when the temperature outside is nice and cool around 55-60*F charging voltage is normal at 14.2v idle and driving. When the temp outside is a little hotter the voltage drops down to 12.4v at idle and as soon as I start driving again it would go up to 14.2v and it does that when ever I stop at a light or something

My car is a turbo 98 civic obd2-obd1 conversion. It's just when ever the voltage reads 12.4v my idle changes to a rough idle and the idle rpm drops to 650rpm compared to 750rpm when I'm idling at 14.2v

Post by **calvin** » Tue Jun 03, 2008 9:14 pm

ectune?

james25 · Post by **james25** » Tue Jun 03, 2008 9:17 pm

Yup P06 ecu with ectune for management.

Post by **Bugermass** » Tue Jun 03, 2008 11:21 pm

check that alternator control is not disabled in your hardware settings, also make sure you have the correct battery ofset tables selected for your injectors.

Post by **calvin** » Wed Jun 04, 2008 12:45 am

cut atl control wire to be sure

greasemonkee · Post by **greasemonkee** » Wed Jun 04, 2008 1:16 am

This all sounds familiar... Will be trying again with new 160 amp alternator soon. What does alt control wire do? Will it charge correctly without it?

JaredKaragen · Post by **JaredKaragen** » Wed Jun 04, 2008 1:20 am

Also, check your wire from ALT to the fusebox.... Check it good, and do a resistance check on it too. I had an issue once of corrosion/deterioration of the wire at the connector; and replaced it with a cut piece of 6Ga wire. Fixed the issue....

james25 · Post by **james25** » Fri Jun 06, 2008 8:33 pm

Checked my cal on hardware settings alt ctrl is not disabled. I got the right battery offset for my RC SL9 440's. I'll try changing the alt wire.

JaredKaragen · Post by **JaredKaragen** » Sat Jun 07, 2008 2:30 am

yeah; I was able to jiggle the wire to get it to work for a while; too bad one day my glove got sucked in by the timing belt and sucked my pinky between the cam gear and timing belt... ripped it in half and crushed it completely... I was lucky it healed but it breaks pretty easy when I shake people's hands :p But the one thing people would ask me is why I would stick my hand there when it's running... Most didn't understand the alternator did not put out voltage when the motor is off, and when you started the motor the jolt from the alternator would cause it to loose it;s connection... spark out in there and loose contact...

james25 · Post by **james25** » Mon Jun 09, 2008 6:32 am

The alt wire from the fuse box goes directly to the alternator right? like straight shot to the alt? I was tracing it the other day and it kind of goes towards the starter, wrapped in one of those wire looms. Between the humidity and the damn mosquitos I didnt get far.

JaredKaragen · Post by **JaredKaragen** » Tue Jun 10, 2008 12:29 am

it's big and white; goes through the engine-side wire harness... that's how you can tell what one it is.

Bindegal · Post by **Bindegal** » Tue Jun 10, 2008 2:19 am

I have seen something like this before... The ground wire going from engine block to alternator was bad, there was some resistance in it. As it became hot, resistance increased = no charge. Naturally, I figured this out only after hours of diagnose AND buying a new alternator. /Allan

JaredKaragen · Post by **JaredKaragen** » Tue Jun 10, 2008 4:00 am

good point right there! I know almost every 95 and below if it has the OEM battery cables and grounding straps they are corroded and have wires breaking loose...

james25 · Post by **james25** » Tue Jun 10, 2008 6:36 am

Man it sucks not having a garage, anyway...Bindegal is talking about that skinny wire thats bolted to the back of the alt? besides the B+ plus wire and the 4-plug wire theres a skinny wire bolted on the housing of the alt. Thats the ground wire from the block to the alt?

Bindegal · Post by **Bindegal** » Tue Jun 10, 2008 6:51 am

Yes it is. And IÂ´m almost certain this is whatÂ´s causing the problem. /Allan