AzG35

I have a 99 Si, converted to OBD1. I just recently converted from a Kenji Chipped P28 to a Hondata s200. The car ran fine on the P28 and VAFC and the voltage always stayed above 13.5 volts while the car was running. After changing over to the s200, the voltage will fluctuate a lot. When cold, the car will be at 14 volts at idle, but once it warms up, it will drop to close to 12.0-12.2 under 3000 rpms. Its very strange, its extremely noticable when the headlights are on. The lights will dim under 3000 rpms unless the car is decelling with the clutch out. This also happened when I put a stock P72 ECU in my car as well. Has anyone ever seen or had this happen? It never did this with my chipped ecu, which is very odd. I don't have problems starting the car either. The Battery light does not come on either. Any comments?

AzG35

Nevermind, figured it out

PHiZ

Care to share?
-PHiZ

AzG35

I guess OBD2 cars have a different alternator wiring setup as OBD1 cars. So when you convert to OBD1, there is a wire that is not used that goes to the alternator. This wire actually changes the voltage that the alternator sees and causes the regulator to shut on and off. This wire is called ALT-C, located at A16 on the OBD1 side of the harness. If you cut/remove this wire from the harness, the car charges like normal again.

PHiZ

Thank-you, excellent information.
I thought it was going to have something to do with ELD (Electronic Load Detector) pin D10 on OBD1, I was wrong.

-PHiZ

AzG35

I think there might be a relation to the ELD. I found that the problem never happened with my Kenji Chipped P28, but would happen with a stock OBD1 ECU. I think you can disable the ELD in a chip and allow it to function with the fix. Hondata actually emailed me back with the same info I read on one of their forums as well

sp00led

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AzG35 &raquo;</TD></TR><TR><TD CLASS="quote">I think there might be a relation to the ELD. I found that the problem never happened with my Kenji Chipped P28, but would happen with a stock OBD1 ECU. I think you can disable the ELD in a chip and allow it to function with the fix. Hondata actually emailed me back with the same info I read on one of their forums as well</TD></TR></TABLE>

AzG35 you have provided me with the most useful information I and my tuner have ever recieved on honda-tech. I disabled the ELD and this fixed my electrical nightmare. I was convinced I had a grimlin in my car and I have spent stupid amounts of time/money trying to figure this one out.

THIS THREAD
My car finally idles like a stock car again I can not say thank you enough!!!!!!

riceburnerryan

on the topic of voltage, i have a voltometer in my car *it came with the car* i dont know how accurate it is but it starts out over 14 and when my car is at operating temp, if i turn on my headlights, rear defrost, and heater it drops to about 12. i think this is normal, but i heard it could be my alternator??

sp00led

Anytime my car while running went under 14v it ran like ****. Not sure if this is your problem but if your only getting 12v while the car is running then you definantly have some issues to address. Good luck

riceburnerryan

i went out and ran my car today, waited to get to operating temp, and it didnt do it today... so i have no idea i even had rear defroster, heater on full, and brights and everything.. never dropped under 13