I put a B18C1 into my 1998 Civic EX aout a month ago. The alternator that came with it ended up going out. So I put a new one it.

When I start it up the voltage is fine, anywhere from 13.8-14.4. After 10 minutes or so of driving, the voltage of the battery will drop and hover in the range of 12.2-12.5. There are 2 ways is raises back up:

1.) I take it to 4000 RPMs. When a hit around 4k, the voltage will jump back up to normal. Then drop when I let it rev down.

2.) I let off the throttle. So when it drops to 12.5 volts and I'm driving, I let off the throttle, it jumps up to normal. As soon as I put my foot on the throttle again, it drops back to the 12.5 range. Doesn't make sense.

Now when the voltage drops, it doesnt always stay in the 12.5 range. It will go back to normal stay, and drop back down sometimes.

Also when I am idleing and it goes to 12.5v, the idle drops to 4-500 as opposed to the normal 750.

Anyone have any idea what would cause this? Thanks in advance.

 

hmm.. all your connections good?

 

What's running? Is the radiator fan running?

 

To my knowledge, all connections are good.

My radiator fan runs when im at idle for a while??

It does the same thing whether I am using all or no electrical devices.

 

I'll find my fluke and test it out tonight.

 

voltage under 13.5 with load on the altenator means that the altenator is on its last limb......need to change it

 

Its brand new!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote"> Its brand new! </TD></TR></TABLE>

Got the receipt still? I've had this happen to me. My alternator took a **** on the parkway one night, so I went to buy a new one and noticed it was reading lower than the norm. Took it back, they checked it and it read fine, however I insisted on just exchanging it. Took the new one home, installed it, and all was well.

 

the eld makes it do that, my wifes civic does it. it has to be over a certain rpm, or have a certain current draw before before it goes up to 14v. the honda service manual has a flow chart of all the reqiurements that the eld has to have for you to get 14v. you can chip your ecu and turn it off and it will stay at 14v, thats how my civic is.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JSPECSIR &raquo;</TD></TR><TR><TD CLASS="quote">the eld makes it do that, my wifes civic does it. it has to be over a certain rpm, or have a certain current draw before before it goes up to 14v. the honda service manual has a flow chart of all the reqiurements that the eld has to have for you to get 14v. you can chip your ecu and turn it off and it will stay at 14v, thats how my civic is.</TD></TR></TABLE>

I need to look into this, i have been having a bad idle problem with mine, replaced the alt. because i was getting funny readings and my lights were really dim, it helped my dim lights but i still have a low low idle, could it possibly be a bad eld? what program allows you to turn off the eld?

I also find that by turning on an accessory like the lights or the ac my idle goes up to normal, do you have this same effect?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by clemsonteg &raquo;</TD></TR><TR><TD CLASS="quote">

I need to look into this, i have been having a bad idle problem with mine, replaced the alt. because i was getting funny readings and my lights were really dim, it helped my dim lights but i still have a low low idle, could it possibly be a bad eld? what program allows you to turn off the eld?

I also find that by turning on an accessory like the lights or the ac my idle goes up to normal, do you have this same effect?</TD></TR></TABLE>

well, my idle does go up if i turn on headlights, a/c or fan but mine does not idle that low (usually at least 500-600)

to OP: sounds like you got a defective "new" alternator

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by clemsonteg &raquo;</TD></TR><TR><TD CLASS="quote">

I need to look into this, i have been having a bad idle problem with mine, replaced the alt. because i was getting funny readings and my lights were really dim, it helped my dim lights but i still have a low low idle, could it possibly be a bad eld? what program allows you to turn off the eld?

I also find that by turning on an accessory like the lights or the ac my idle goes up to normal, do you have this same effect?</TD></TR></TABLE>
you can turn it off in crome, uber, whatever. yeah my wife used to leave the climate fan on low all the time and it would stay up at 14, if you cut it off it would drop and idle would go down too. if you want one day unplug your o2 on top of the tranny so you throw a cel (easiest way i know to get it into open loop), then drive around and see if it stays at 14, if so it was eld controlling your voltage, because it doesnt function if its in open loop, at least not on a p28. its a long story why i know this, but give it a try and see what happens. let me know. you dont have to leave it that way just try it, see what happens, then plug it back in so your cel goes away. (30 some miles i think, or pull batt. terminal to reset for obd2)

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by c1v1c98 &raquo;</TD></TR><TR><TD CLASS="quote">To my knowledge, all connections are good.

My radiator fan runs when im at idle for a while??

It does the same thing whether I am using all or no electrical devices.</TD></TR></TABLE>

yeah, just had the same problem. you see since the alternator went out it most likely damaged the battery (mine did). the battery is low on cranking amps. my battery was doind the same, it through the battery light on & had it double check by another store and found out tha it was low on cranking amps. i replaced the battry and problem solved.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JSPECSIR &raquo;</TD></TR><TR><TD CLASS="quote">
you can turn it off in crome, uber, whatever. yeah my wife used to leave the climate fan on low all the time and it would stay up at 14, if you cut it off it would drop and idle would go down too. if you want one day unplug your o2 on top of the tranny so you throw a cel (easiest way i know to get it into open loop), then drive around and see if it stays at 14, if so it was eld controlling your voltage, because it doesnt function if its in open loop, at least not on a p28. its a long story why i know this, but give it a try and see what happens. let me know. you dont have to leave it that way just try it, see what happens, then plug it back in so your cel goes away. (30 some miles i think, or pull batt. terminal to reset for obd2)</TD></TR></TABLE>

I will try that today and see what happens!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by clemsonteg &raquo;</TD></TR><TR><TD CLASS="quote">

I will try that today and see what happens!</TD></TR></TABLE>
cool let me know what happens

 

What is the "o2" on top of the tranny? Are you refering to the o2 sensor that plugs into the header? I would like to try this also, so I can rule out my battery being shot. I may pick up a new battery today, or have mine tested.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by c1v1c98 &raquo;</TD></TR><TR><TD CLASS="quote">Its brand new!</TD></TR></TABLE>
New doesn't always mean working 100% I've put four alternators into a car before I found one that actually worked 100% , Check the return cable from the Alternator to the Battery, once in a blue moon something happens to them.

 

well it turns out mine isnt as low as i thought, at least not today, i checked the voltage today, with the car completely cold i put the multimeter on it and it read ~14.06 volts, and let the car warm all the way up, momentarily switching on the ac or the lights, and the voltage stayed within that range. I took it for a spirited drive, came back and put the meter right back on it and it read ~13.95 volts, so mine is staying in range, I did notice that if i pulled off a vaccuum line like the cruise that the idle got magically better, so it seems that i dont have a vac leak, but that i actually need one, so im gonna take my throttle body off this week, pull it completely apart and clean it up real good and then see where it goes from there

 

I was at autozone getting some leather conditioner and decided to just pick up a new battery. I put it in and let it idle while I was cleaning my seats. The voltage stayed at 13.9+ for about 15-20 minutes at idle. I backed out and shortly after I put it in 1st, the voltage dropped to 12.5. I'm hoping I can still take this battery back. Anyone have any other ideas?

 

Mine has the same problem. Has had 2 alts and 2 Batts. Still likes to drop in the 12s for no reason.

 

Please create a new thread rather than bumping an ancient one.