Low Voltage issues

[acidflux]

Let me state that I did in fact research this and I couldnt find much that was helpful.

I have a 1991 Talon TSi AWD. The volts Im getting with everything connected hangs around 10.8 and gradually drops which tells me that my alternator is not charging. When I disconnect the negative terminal with the car running, the voltage spikes up to 13.5. This told me my battery is bad. The battery is a month old and I took it back to autozone to have it tested and it tested good and needed a charge. I had it charged at autozone for free (30 mins). As soon as I put it back into the car, same problem. Im sure that if I had done a 2amp trickle charge over night the voltage woulda been alot higher but, once again it was in the 10.x's. This morning I tried disconnecting the negative terminal again to double check my alternators capability. This time the voltage was at 6.8. Perhaps my alternator was on the fritz and finally petered out?

All the while this stuff is happening, my o2 sensor voltage is going haywire. Sometimes while cruising it will perform normally. The problem it's giving me is that it is staying between 2-4 volts. Sometimes it works ok but usually not.

Lastly, my ecu has leaking caps. Could this be causing the o2 problem and also draining my battery thus overworking my alternator till it died?

Im at my wits end with all of this and this car is my only means of transportation. My battery cables are all good, I even replaced ones I suspected might be bad. The only thing I havent done is put a test light between the negative battery terminal and the actual cables.

Ive got a spare alternator but I have issues with it due to the stock belt size being too large and the inability to adjust it properly. I need to research a smaller belt so I can properly adjust the tension. As for the alternator thats actually on the car, its nice and tight, the belt is brand new, and it tested good 2 weeks ago at autozone. Maybe it has died since that test due to the 6.5ish voltage output with battery disconnected.

Any ideas, thoughts, anything?
Thanks.

 

[blackbyrd]

Hey man.
Double checked connections on the alternator? Checked the fuse? Belt tension?
While your car is running use a voltimeter and probe the positive output on the alternator, and ground on the chassis.
If you get less than 14v your alternator is defective.
It sounds like your alternators not putting out at all.
Take it back to advanced auto and have it tested. When it's tested bad, request your money back from them. I've gone through 4 AA alternator, as well has hundreds and hundreds of people on these forums. They are notorious for going bad very shortly, probably because they have outsourced some kids in china to rebuild it for them. It would be a better route to have a reputable shop around you build yours, or goto jnztuning, or find a new HO alternator.
Good luck!

 

[acidflux]

Im in luck, I somehow fenangled my buddys alternator on there and got it tight. Charging steady at 13.5. I guess when I had mine tested originally it was good and slowly fried itself over a week. It was just going bad, that was it. Now, im gonna have mine rebuilt so I can reinstall it that way I know it fits. I dont know why but the alternator off my buddies car (1g) wont fit on mine worth squat. The tensioner and brackets are diff on our cars yet we both have talons. Oh well, It's working for now.

Now I gotta figure out why my o2 sensor voltage is hovering around 4.6 volts at all times. I suspect bad ecu since my ecu is in fact going bad on me. Ill know in 15 mins when I try my buddies ecu out. Thanks for the help and any input on the o2 volts would be nice too.

 

[acidflux]

Ok no dice on ecu fixing the o2 sensor voltage that constantly runs between 4.3 and 4.6vdc. I dont know whats causing this but one time the wire for my turbo timer popped off the ecu wire (o2 wire) and it caused the same problem. I looked at the wire and everything was secure. Must be a problem elsewheres.

 

[blackbyrd]

I thought the oxygen sensor was just supposed to read from .1-.9v ..
I would double check those connections again, even redo them. Did you soldier it or use a crimping connector? Did you hook up the turbo timer properly?
You oxygen sensor might be bad.. It should throw a CEL if it is I thought..

 

[Auto RS T]

Sounds like the o2 itself is taking a crap.

I actually have a problem right now and I believe the o2 sensor to be the culprit with no CEL.

 

[blackbyrd]

Yeah, I guess it won't always throw a CEL. Is it going in open loop mode?

Heres the best I have to check out the sensor:
Warm up the engine to normal operating temperature. Disconnect the oxygen sensor electrical connector, and connect a voltimeter. Connect the positive probe to terminal 2 on the sensor connector, and the negative to a ground.
Open and close the throttle a little bit, looking at the voltage.
When the speed is increased the voltage should increase to 0.5-1.0v. When the speed is decreased the voltage should drop to about 0-0.4v.

Check the supply voltage to the oxygen sesnor with the ingition switch in the acc/on position(engine not running).
On the harness side, check for battery voltage on terminal number 3.
Also inspect the oxygen sensor heater. Disconnect the O2 sensor electrical connector and connect an ohmmeter between terminals 3 and 4. There should be approximately 12ohms at 68*F.
Also inspect the O2 sensor heater ground circuit. Disconnect the O2 electrical connector and connect the leads of an ohmeter between 2 and 4, in turn, and ground. There should be continuity.
Also check the output voltage of the O2 sensor, at different rpms.

 

[acidflux]

Awesome plan, Ill get right on that after work. I suspect it might have something to do with the turbo timer but It very well could be another issue. I wired in the turbo timer with wire taps and butt connectors. I know they arent the best but it was all I had. Maybe after checking out the o2 sensor and ohming out the wires from the harness to the ecu and a few voltage checks, I can isolate the problem moreso. The car does run REALLY slow with this problem so I suspect that the wiring may have melted together near the o2 sensor. I'll just have to dig into everything with a multimeter and see what I get. 4.3-4.8 vdc on an o2 sensor should be impossible on a 1g. It is my understanding it should never go above 1.0. The car is in fact running in open loop I believe because the voltage doesnt cycle like its supposed to according to my turbo timer and a/f gauge. It just stays locked in in the deep 4.x volts area. It's probably some bum wiring somewhere that needs attention. Thanks again and Ill post an update as soon as I find out more.