Charging system, and some other issues

Issue 1-Charging System
Recently, my idle has been rough when a load is put on the electrical system. I'll go ahead and list everything I've done/checked:
Alternator: checked good, it is the original alternator
No charge light
Voltage at idle with no load or accessories on: 14.48-14.51 V
Voltage at idle with headlights (low beam): 12.54-12.62 V
Voltage at idle with headlights (high beam), A/C on, cooling fans running, HVAC blower on high, rear defroster on, hazard lights on, brake pedal depressed (everything that could draw from the system): 11.94V-12.05V
Voltage at 2000RPM with everything on that could draw from the system: 12.02V-12.24 V
Voltage drop between positive battery terminal and alternator terminal: 0.01 V (basically non-existent)
Thoroughly cleaned battery posts and cable terminals: no change in results
With a full load on the system it idles between 738-762RPM (mostly stays 742-748) which is in spec with the 750 plus/minus 50 RPM, when EACV is unplugged it idles between 645-654 RPM, in spec with 650 plus/minus 50, and the timing is spot on
With a load on the system, as load increases, the idle becomes rougher (as in more vibration can be felt inside the car) (worst when brakes are applied and headlights are on)
Sorry if that was too detailed, but does anyone have any ideas? I've fixed quite a few electrical problems on this car but this one has managed to stump me.

Issue 2
While driving, above 2000 RPM, the keys like to make noise from vibration, any ideas of where this vibration might be coming from?

Issue 3
There is coolant in the hose leading from the bottom of the air cleaner housing to the throttle body as well as the fact that the hose smells strongly of coolant, the bottom of the air cleaner housing also has coolant on it, the only place coolant would get into these two places is from the coolant that is running through the bottom portion of the throttle body, or at least that is what I figure, neither of the two hoses are leaking so it leads me to believe that the lower portion of the throttle body is passing coolant internally, thus causing a slow loss of coolant, and maybe having to do with the rough idle?, would this even be a possibility?

Any help with this would be appreciated, and I apologize for the rather long post.

You might be expecting too much. These are Japanese economy cars, not German V8s. Our engines just transmit a lot of energy to the cabin when the idle gets down around 750. If you are getting unbearable vibration, then you might start looking at motor mounts. I'm not sure what kind of gas you are using, or when your last tune up was, but those things can also affect idle smoothness.

Engine was just rebuilt 2500 miles ago, i did it myself and know it was done right, but I know for certain that the charging system voltage is directly related to the stableness of the idle, when no load is on the engine there is no vibration whatsoever, so the fact that the voltage is dropping substantially is the cause of the problem

My favorite is watching the idle dip along with the turn signal when I'm at a light

I'm thinking either corroded battery-to-body ground or weak alternator.
Follow the negative batt cable to where it bolts to the body and clean that up.
You should also check/replace/upgrade your engine ground wire, it's a small wire from the valve cover to the body

Anyone else have any other ideas?

How's your battery? At Idle I wouldn't expect the charge system to keep up with the full accessory load, but I wouldn't expect the voltage to sag that far from this load on the battery (at least not for a while....) maybe have it load tested to see how it holds up.

...My Napa Gold battery is almost 11 years old now, (amazing life), weak, needs replaced, but still cranks & starts right up, no problem. (yeah, I need to get a new one soon)

I have a carb, so idle smoothness will be different than Fi, but mine will start getting loopy idle below about 500rpm. At 700-750 it's quite smooth. What do I attribute this amazing performance too? perfect valve lash adjust, slippery synthetic oil, a Redline SI-1 licked clean carb, valves and combustion chamber.

Quote:

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Originally Posted by zenapup

so the fact that the voltage is dropping substantially is the cause of the problem

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The voltage is within normal ranges though.

You call 12.24V with everything on with the engine at 2000RPM normal??? I thought it wasn't supposed to go below 12.7 V?? Since 12.7 represents a charged battery, I would think it is discharging

12V with all that stuff on at idle is normal. I mean, if you really need to start changing out parts, don't let me stop you.

But that wasn't idle, it was 2000RPM!!!!!

12V at 2000RPM is definitely not normal. Have you had the output of the alternator tested? They can put out voltage all day long, but put out next to no amperage. It doesn't take much to keep a battery charged, but we are talking 30+ amps under a full accessory load. I suspect this is a bunch of your problem.

As for the key rattle, it's normal. Mine does the same thing. Could just be resonance frequency, could just be vibration through the steering column, etc etc.

After re-reading your original post, I'm fairly certain the alternator is your problem.

Flip your meter over to AC voltage and meter the output of the alternator. Good way to see how the rectifier in the alternator is doing. If the rectifier is half shot, you will not be getting proper DC voltage off of it to charge the battery. Good down and dirty way to verify an alternator issue.

Could be, i'll check it again, I should have known better than to trust the auto parts store and their testing of it, even though I watched the guy test it three times and all said good. It could very well be the problem, as it is the original alternator from 1988.

Quote:

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Originally Posted by zenapup

Could be, i'll check it again, I should have known better than to trust the auto parts store and their testing of it, even though I watched the guy test it three times and all said good. It could very well be the problem, as it is the original alternator from 1988.

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On the flipside anyone of those accessories could be pulling to many amps. With out measuring amps youll never no.

I made a chart of my car its under my name if you do a search under my name.

Wp

I didn't think it would do it.. but my original '88 alternator with 11 year old high internal resistance battery, idling at about 600rpm with defroster, high beams, blower on high, radio (no A/C here..) all acc on,,, still reads 13.2 volts on the battery. A few more RPM up to 1500, and it reads the full 14.5 charging Volts.

Am I the only one who sees that we are diagnosing a rough idle here? There is no charge light, no dead battery, no dimming headlights. Are we really going to send the OP off to buy a new alternator for this? For a rough idle, I can think of a lot of things I'd change before the alternator.

It is the 12ishV at 2k rpm that has my curiousity piqued.

the simple answer is the altenator is prob worn out.
the brushes will be worn to a point that they are only just running on the slip rings. they can handle the load of running the car with no load, but cant when you turn on any accessories.
pull the altenator off, remove the cover off the back and remove the brush holder. the slip rings will probably have a rough burnt look from arcing.
the brushes will prob only just be poking out of the holder, there should bout 10mm poking from the holder.
if the brushes are ok and the slip rings are shiney, suspect the rectifier, but that is fairly rare with denso alts, unless you have been running a battery that is stuffed and the alt is charging its arse off all the time and the diodes have been overheated.
never trust what an auto parts place tells you bout an alt unless the guy doing the testing is a qualified auto electrician.
the idle getting rough with all accessories at idle can be fairly normal, its a lot of extra drain on the motor and the ecu cant always compensate for this completely with the idle control.
go and get an auto electrcian to check the charging system properly and see what it would cost to rebuild the alt if needed. better to have it done once properly, than to keep going backwards and forwards with shithouse reman units that are never rebuilt properly.

I would never let anyone rebuild it, I would do it myself, brushes are ok but the slip rings are grooved in the two places where the brushes run, I'll post a pic later

Cleaned battery grounds, seemed to help a little, and I do mean a little

Were you able to get any amp draw readings with your accessories on?


wp

Sorry it took me so long to respond, i've just had a lot of other stuff that I had to get done and I finally got around to working on this problem again. With a new OEM battery installed, my readings are now as follows at IDLE (750 RPM):
14.45-14.52V with no load
13.92-14.21V with all accessories on (fluctuation between these two readings as the turn lights flash)

With this, I'm going to say that solved that problem.