Ok, i just did these test to see if they worked before i put my car into the conditions ( also was still in open loop so was idling high and also in park ) where it only has like 9 or 10 volts ( everythign goes dim and checked with volts meter ). Here is the conditions i'm having. I go into town at night and say i have my headlights on and my blower fan on inside the car and i come to a stop. My volts drop almost to red and read like 9 on my volts meter. That is WITHOUT anything else on. ex. Stereo, fog lights, my fans, turnsigles dome lights. I mean without ANYTHING! To drop that low is no correct and i know it. I can litterly make my car die if i have these ( * ) on and i've been cruisin town for a while. * Headlights, foglamps, stereo ( not even bumpin extremely hard PLUS a power cap ) blower motor, fans. It will go almost to 8 and i say turn on my hazard lights and kick on all the lights inside my car just dies cause lack of voltage i guess. Its funny but not ya know. Once i get it the rpm ups my voltage goes up but only to like 12.5 to 13 cause after having to sit at the stop lights its drawnin more juice off my battery than what my alt can put back into it. ( on the side note. Just the headlights on and nothing else it will still drop way down after awhile, just takes longer cause my batter is at full juice ya know ) Once i get on the interestate to go home BAM! around 14 where it should be cause i'm running 2 grand plus for a period of time. I can run around town holding a high rpm but never have a long enough straight away to get up that far. ( big cruise strip. Probley a mile plus on a section before i have to stop again! and that should be plenty of enough time) Every place says i have a good alt and its a BRAND NEW battery. ( Looks like a bran new alt too!!! was there when i bought the car in feb and the guy said he just put it on so i'm assuming he "tried" fixing this problem or some shiznet) The alt says its reman. and its a az duralast.... OH btw it idles at 600 and has brand new belt also.... Also when i did these test i noticed this noise. With the key on and nothing else on my alt makes a very high pitched quiet whine.. Almost like the key is in the ignition but 100X quieter. Had to put my ear about 4 inches from alt to realize that is where its coming from.... Wtf is that about!

Ok now u know my problems and this is why i tried these test....

Ok what I got the steps in bold and down below is what i expeerenced... maybe its just me... i donno never hurd of these test but i tried them and here are my results number to whats in bult in the quote....

1. Mine was reading like 14 something ( Cold start not in gear )
2. I did it even though it don't sound right. Wires got hot on my meter ( lol knew it would ) and it read nothing......
3. got no reading......
4. still no reading......
5. hmmmmmmmmmmmmmm stilllll no reading......
6. ummm nope gettin 0.00 still

most of these test don't make sense to me. I had to re-read them about 10 times cause i was like wtf and he expects to get a reading like this.... But tried it. So ummm wtf did i do wrong or is the test wrong or what......

Thanks Derrick

 

most cars that are idling are in open loop anyway. more often then not (unless you ahve a heated O2) the o2 sensor cools off enough to cause bad readings, plus the TPS detects idle condition if set right and will go back to open loop.


your power cap isn't going to prevent draw on the battery all it is going to do is buffer your peaks. the avg battery draw IS STILL THE SAME.

1) 14v sounds a little high unless it is just fresh off charging. it should drop to around the 13 range fairly quickly though

2) it shouldn't get hot if you have it on the voltage setting but it would with a amp setting on the amp setting. which did you use? the high ohm internally on the volt meter should prevent much current from running through it. though the amp setting uses very low ohm resistor and allows quite a bit through instead.
the rest sound about right with very low or no reading.

with the noise I think it is something with the alt. either how the alt in connected or with the actual alt itself. do you by chance have a spare?

 

Underdrive pulleys would make the voltage drop at idle. Also the wrong size pulley (larger) on the reman. alternator alone will kill the voltage at idle. That was the problem on my girl's s-10 zr2.

 

the only reason the leads on your test meter should get hot is from the hot air coming off your radiator. i should have said this in the other post, did you have your meter set to read DC voltage?

what a voltage drop test is for is to see if you have any connections that are poor, the closer to 0.00 you are the better, its when you get a reading that there is a problem. i don't like anything over 0.25 on any single connection & even that is high.
my meter will show a small amount of voltage from the alternator to battery positive, it will even show up too 0.05 from the battery post to the battery cable on a top post battery with the motor running & everything turned on, but i did pay over $300.00 for it, it is very sensitive.

it sounds like your alternator is dying on you, they shouldn't make any noise with the key on & engine off. if its an autozone or similar alternator, i don't expect them to last for very long, we replace a lot of them where i work at, most when they are only a few months old.

 

You mentioned that the previous owner installed a reman {A-Z Duralast) alternator. There is a possibility that the alternator is not what you think it is. Despite the markings on the case, the components used to reassemble the alternator may not be matched.

Many rebuilders will get a container of cores from their collections points. They clean everything, then disassemble everything. One person cleans, another knocks off the sheaves and splits the case, another pulls the regulator and heat sink, another pulls ther bearings from the rotors, and another pulls the stators. All these parts go through another cleaning process. Someone else inspects the rotor windings and shafts, another person installs new bearings on those rotors which "pass" inspection, another person tests stators and either dips/bakes new insulation or rewinds them, someone else cleans heat sinks and tests diodes, etcetera. The problem is that all the "good" rotors go in one container, all the "good" stators end up in a different bin, the "good rectifier/regulator assemblies show up in a different box, and a few people start assembling all the "good" parts. When they are completed, each one is tested to make sure it will produce output current, has no reverse leakage, and no unusual noises. They get placed in a brand-spanking new box with a proud certificate which gaurantees "quality" of the assembly. No one has a clue whether the stator in that "104A" alternator case was from a 37A unit, a 63A unit, a 104A unit, or a 140A unit. You look at the "like new" alternator and the stamping on the case reads "104A" and presume that's exactly what you have. Well, maybe not. And then you start having charge rate issues at lower RPMs (typical on an EFI engine) and assume it must be something other than the "new" alternator. Only a load test with an in-line shunt is going to tell you whether the alternator is any good. You can take voltage readings all day long and only have clues about whether the alternator is working (or the correct size) or not.

 

Wow, I didn't realize how they were rebuilt, that's an informative writer-up Vader.

I was thinking along the lines of not having the right current output from the alternator, which is pretty much what Vader just said. If the alternator can't produce enough juice to keep up the the demand at low rpm, but can when at driving speed, it will re-charge the battery which will then carry the load for you when the alternator isn't putting out at full capacity.

I don't know which model F-body you have but my 86 IROC with A/C came with a 140A alternator. If you have a TPI car and AC, I am guessing you will need a high current output to keep up with your car's demand. I had to have my alternator rebuilt back in 93 or 94 for this reason...

 

You can have your alternator current-tested on the vehicle. They test it under load both at idle and revved up to see if it's in spec for output. I suspect yours is not up to snuff.

I've often found that cheap rebuilt alternators do fine when revved up but can't hold adequate voltage at idle. I replaced on on my Wife's 98 Blazer this spring and the new one clearly drops voltage more severely at idle than the stock/original one ever did. Nothing like you're experiencing, but noticably weaker than stock at low RPMs.

 

First off i have to thank vadar cause he is always answering my threads even though some seem the same. Just i do a lot of searching on here to try and figure out other possibiltys on whats wrong with my car and then post a new thread trying to get deeper answers. Your answers always make things a lot brighter. Thanx

Ok... to the guy that posted the open / closed loop. I have to disagree with you cause car is in open loop until a certain temp ( or a computer timer if o2 sensor screwed up ). I do not have a heated o2 sensor and once warmed and goes to closed loop it stays there. No matter if i'm running 120 at 5grand or sittin at a stop light at 600rpms. So the whole thing you said about car going to open loop at idle wouldn't be correct....

Also a question for whom ever...... How do i test to see what amps my alt is puttin out.

Also what stock car with a stock alt can i pull the pully off of to make mine smaller. The only reason i ask is because i don't have a spare/ the orginal and when i buy a new one i want the pully to be as small as possible.. That way i hold good charge at idle at night with my extra's.

Also i seen someone post something about my power cap and don't remember excatly what they said. But i can say with it hooked or not hooked up ( amp and power cap that is ) i see no difference unless i'm bumping my subs.

The faint whining noise i hear is defently coming from the alt. What could cause that. ( key on motor off ) My alt is the 3 wire setup. One back to battery and then a plug with 2 hots coming off it. I leave the key on and stand by the alt listening to it and unplug that plug it stops and as soon as i plug it back in , it starts to whine, hum ( some sort of noise like that ) again. I think the alt is junk anyhow but maybe something else could be causing that whining!

Thanks for all the feed back and help everyone. I am going to buy a new alt from chevy dealer but want to make sure just alt bad and nothing else made it go bad ( start the whining )

Derrick

 

not to get too far off topic but can you verify that? at idle I admit I am not sure but there are other times when the ECU should go into open loop even when fully warmed up.

 

sure i'd be happy to explain and if i'm wrong please someone correct me but i'm 97% sure i'm on the beatin path here. I was having idling problems and in my research i came across open and closed loop questions and decided to do research on it myself that way i understood it and could decide if this could have a playing factor on my idle ( btw it didn't )
This infor is for my tpi. I donno if it aplies to a tbi or not but i assume it would. but thats my 2

Open loop - happens when the o2 sensor is not puttin out enough resistance for the computer to let it take over. So the computer ignores it the o2 sensor in open loop ( that is why its called open loop ) and adjust your fuel / timing off of you MAT Sensor and collant temp sensor. Your computer is also using "default variables" in open loop so your car is actually running rich cause the o2 sensor is not operations yet. Once the exhause ( o2 sensor has been heated enough to give an accurate reading the car goes to closed loop )

Closed loop - Now the o2 sensor is heated enough to give an accurate reading to the computer so it goes to close loop. Now the o2 sensor can tell the computer if your running to lean or rich and can change your fuel ratio from there.

So if you are going into open loop during normal operating conditions which would be car being warmed up and operational temps ( default about 190 unless lower thermastat is installed ). I think you might be having some sensor problems. But wo'nt go into details unless you actually are and i'll be more than happy to explain more.

edit-----------
oh btw i re read your first post and the tps shouldn't be puttin it back into open loop on idle.. I have mine set on .54 and stays in closed. If your tps has no idea if your at idle or not just where your foot is at in the gas. Ex. foot out don't excatly meen idle. What about driving down the road at 55 and u just let up... TPS can't tell between the 2. That is what the ecm is for and all these other sensors working together. Also i run a 160 thermostat and my o2 sensor gives me the proper reading from starting it in the moring ( 4 am ) to long road trips on the interestate all the way up to crusin town.

 

Ok now back to my alt questions. Just a reminder 91 305 TPI

I'm still trying to locate why my alt is making this stupid noise. ( probley the alt shot but ya know want to make sure.)

Ok. I know it would happen with key on motor off. So i whiipped out the chiltons book tonight and read the alt section of it. Also went back to studing the wiring diagram and came up with a couple of questions.

First off i went back through and retested everything now i know its actually safe and what the reason i was doing it for. Everything tested 0.00 ( start of the thread ) Started testing my wires and making sure it was making a good "loop" cause the book said if it didn't that would cause bad voltage so though what the heck i'll do some testing. Everything checked 100%

Ok i have realized if i take the fan fuse out with key on motor off the humming quits. I know should have realized it would from the get go cause its not hot with key off but ya never know.

I got a 2 wire plug. ( but on the alt it self it it has 4 little prongs inside and i'm only currently using 2 of them. Never paid that close attention when swapping out alts before but is that normal or maybe he put wrong alt on.... I know the guy that wrenched on this car before me wasn't puttin the correct parts on. They were just a couple of sensors but made a world of difference. ) I got a red one that runs down to my starter and connects with the big black wire that goes back to the positive side of my battery. Then i got a brown one and my books says it goes to the fuse box.

After studing the wireing digram i guess i've lost myself tonight and i'm not sure how this fuse plays a big factor in the alt part. I know its blow/not there the alt don't work but how.... I look at the digram and it says on one page ( body wiring ) that it goes from alt to the fan fuse. Then i jump over to the engine wiring page cause the body wiring shows me no more of the brown wire and its saying that the brown comes off the fuse box ( hot in run ) and then pretty much does a 3 way splice..... one way to the gen. one to the coolant fan relay and one to the aux coolant fan relay. I figured if it blew it would just keep my fans from coming on... Um i'm dumb founded cause i know there is more to this just this gay book aint telling me.

So maybe a little explination will help me with this problem.

BTW i was doing some rewiring on my fans ( before i found this site ) and must have wired something up wrong ( fixed now ) but wanted a switch to kick fan on whenever i wanted but yet wanted the system to take it over if it got to 222 F. Well I was in town one evening and had fan switch on everything was working good and forgot to turn the switch off ( didn't even think about it ) when i kicked my a/c system on. Of course the computer took over and kicked both fans on. Well..... ( had idling problems before that and sometimes would charge good and never drop and other times it would drop down some but i think that was cause of idle ) however i had it wired, don't really remember, but i guess it surged my system or something cause all the i looked down a few minutes later and my alt wasn't working. ( switch now getting turned off ) About the time i get home ( only had about 10 blocks to go so said screw it i would run it home on battery ya know ) it starts to work, bamb back to 13. Well no sooner i get it in the drive i notice lights are dim and look down, back at 8 or 9. Get out, check some things and realize my fan fuse blew ( probley cause how i had that stupid switch wired up ) so i replaced it and alt worked again. Now i just don't think as well. I also realized since then that my primary fan wouldn't work and thought it was relay and replaced it. That wasn't it. So did a little screwin round and got the primary to work but not secondary. So i now have it wired if i use the switch of the system kicks the primary fan on it also kicks the secondary on. I used another relay and its actually quite well though out.
Also since then with the key on and motor off if i turn on my a/c system my clutch will engage. I didn't thinkn that was normal. So know you know everything that there is possible to know on where i stand for the diagnostic of my car.


SORRY SO LONG! I get carried away with details.

 

KOEO, turn on the A/C, and the clutch will engage. That's fairly normal.

Don't overthink it. Just load test the charging system and solve it. There may be more than one issue at play, but solving the charging problem will take one off the list.

 

missouraman the stock o2 sensor is should be fairly limited on the a/f ratio it can detect which is mostly just cruise loads. much above a specific load the car should start to ignore the o2 sensor readings since 14.7 isn't the fuel ratio your looking for anymore but little richer then that and richer then what the narrow band can detect with any accuracy (unless the car is using a wideband and the ecu can handle the 5v signal and read it correctly). at this point the car goes into open loop again. that part I'm sure of. what I'm not sure of though is the GM fuel system handling idle. which the tps should play a part in with detecting idle. most motors seem to run a little rich at idle then compared to cruise and also at idle the exhaust really shouldn't be hot enough to keep the o2 reading correctly either I wouldn't think. IF i am correct which I very well might not be but at idle the car would be open loop as well.

now if vader since he is chiming in could help out and divy up a quick reply to help us both out on this topic it would be over and we both would know.




with the charging system I'm out of ideas myself other then the alt right now.

 

You know what happens when the engine warms up, goes into closed loop, and the 180* thermostat opens up? The engine cools down with the nice shot of cool stuff from the radiator, the computer goes back to open loop, and whamo!
SES CODE 32 Why? because the dam comp. just grounded the EGR solinoid shuting off EGR operation. Even though you only loose EGR operation for a couple of seconds, the computer thinks it's not working properly or the EGR passages are blocked. I never had a problem with code 32 till I replaced an old half blocked leaky radiator and dropped in a 180* then, It wanted to run between 170* and 180*. After moitoring the vaccum signal between the solinoid and the EGR valve and watching the temp. during warmup, open loop, and closed loop, and after warm up, I found out exactly when the comp. was throwing the SES code 32. THE FIX? I went back to the 192* (factory recomended) and the problem went away. I guess if I want to run cooler, a custom chip would be in order huh? It now runs between 190* and 180* and by the time it hit's 200* (like stop and go or drive thru) the fan kicks on and keeps it under 200* I wish I had figured it out before I spent all the money on a new EGR valve and EGR solinoid AND a bottle of Rogane!!!

 

Check the wiring for the amp and the cap. Chances are someone didnt know what they were doing. ...just my guess. I used to work in car audio, and youll be surprised at how some people install audio gear.