Last week I took the green machine ('91 Formula L98) out for a run. It had been sitting for about 2 weeks prior in the garage I rent over on the mainland. It fired right up, and I cruised out to a low traffic road out west of town to get a few acceleration runs in. I did 3 or 4 runs and the car was running great. On the next run it seemed like the tranny was shifting slow. I got on it once more from a stop and the tranny short shifted, and the car seemed to be running slower. Started heading back toward town at that time. The next run I made the engine cut out or backfired twice. I came up to a traffic light, and I noticed the a/c blower was hardly putting out any air. Next the “Inflatable Restraint” light started blinking. I looked at the voltage gauge and it was down around 10 volts. I turned off the a/c and the radio, and when I left the light the engine was bogging badly…it felt like the timing had changed. I got back to my garage, and when I went to put up the power windows, they would not go up. I revved the engine one more time and it started popping. At that point I shut off the engine, went to restart and there was nothing, not even a click. The battery was dead. Now at this point I’m thinking I lost an alternator, but can’t figure out why all the other stuff was happening. It was getting late, so I closed the garage door and headed home. So today, I load up my jump starter, voltmeter and tools, and head to the garage. I’m fully expecting the battery to be dead. When I get to the garage, I figure what the heck, let’s try to start the car. It started cranking, you could tell the battery was low, but it fired up. I let it run for a few minutes to warm up, then revved the engine. It revved fine, no hesitation, no backfires, no popping. I looked at the voltmeter, and it was at a little less than 12 volts, and dropping slowly. I let in run till the voltage got down to around 10-11 volts, now the car is starting to run rough again, and the “Inflatable Restraint” light starts blinking again. I rev the engine and it’s popping again now. I shut it down, and try to restart…nothing…it’s completely dead again. So I pull the battery (a 4-year old Die-Hard), and take it down to Sears to get it checked. The dude puts it on his analyzer and tells me it’s too dead to test, so they throw it on the charger for 2 hours. They check it again and tell me it’s good. I take it back and put it in the car, it fires right up and runs great, no bogging, no popping, no lights, and the voltage is a little higher than 12 volts. Well, the temp in my little garage today was about 125 this afternoon, so I called it a day after that. Next weekend I’ll check the alternator output. Now my question, can low voltage cause all that other stuff to happen? The only thing I can figure is that the computer starts getting flaky at low voltage and screws with everything else. Has anyone else ever heard of anything similar happening due to a low voltage condition, and should I be looking at anything else?
TIA
[ 10. July 2004, 03:22 PM: Message edited by: jimb0 ]
Posted by SS_CarGuy (Member # 2065) on :
I don't have any other ideas myself but I think your theory is sound to me. The only other thing you might want to do is see what error codes might have been set in your ECM........maybe it will help to confirm your theory.
Posted by agmSS (Member # 853) on :
I had same identical thing to me happen many years ago with my '87 Vette. I was driving home with a friend from one of those Corvette Dream & Drive events sponsored by GM when I noticed the display panel for the electronic HVAC controls had dimmed way out like I was driving in daytime with the headlights on. The digital cluster also started fading out and then the car began to run really rough. If I gave it anything more than part throttle, it would bog out, misfire, pop, fart, and almost die out. I managed to limp it the last 30 miles and got within coasting distance of my dealer. The car died coasting down the last hill and I literally coasted it into the dealership parking lot. It was late on a Saturday and the sales guys were just locking up. One of them was nice enough to open up the service garage and my friend and I pushed it into the service area. The following Monday they took a look at it and it was a fried alternator. The battery was also toast, so they replaced that as well. The car ran like new after that and never had that happen again.
The giveaway in your example is the low voltage reading. With a properly functioning alternator, you should see a reading on your gauge above 13 volts. With readings below 12 volts, the battery is discharging and it 's only a matter of time before it drains to the point where it impacts critical electronics. If the battery is still good like you say, throw it on a trickle charger to bring it back up and then you can get the alternator checked to verify that it's not charging the battery. Another possibility is that you have some electrical short somewhere, but my guess is that the alternator is the culprit.
Posted by Oh2xSSivLS1 (Member # 1915) on :
quote:Originally posted by agmSS:
I had same identical thing to me happen many years ago with my '87 Vette. I was driving home with a friend from one of those Corvette Dream & Drive events sponsored by GM when I noticed the display panel for the electronic HVAC controls had dimmed way out like I was driving in daytime with the headlights on. The digital cluster also started fading out and then the car began to run really rough. If I gave it anything more than part throttle, it would bog out, misfire, pop, fart, and almost die out. I managed to limp it the last 30 miles and got within coasting distance of my dealer. The car died coasting down the last hill and I literally coasted it into the dealership parking lot. It was late on a Saturday and the sales guys were just locking up. One of them was nice enough to open up the service garage and my friend and I pushed it into the service area. The following Monday they took a look at it and it was a fried alternator. The battery was also toast, so they replaced that as well. The car ran like new after that and never had that happen again.
The giveaway in your example is the low voltage reading. With a properly functioning alternator, you should see a reading on your gauge above 13 volts. With readings below 12 volts, the battery is discharging and it 's only a matter of time before it drains to the point where it impacts critical electronics. If the battery is still good like you say, throw it on a trickle charger to bring it back up and then you can get the alternator checked to verify that it's not charging the battery. Another possibility is that you have some electrical short somewhere, but my guess is that the alternator is the culprit.
second that!
Posted by BrostalSS (Member # 1830) on :
Alternator! I had a something happen just as you described a few years ago. I wasted the battery limping it home. But since almost everything is computer controlled, low voltage will start making things run a little goofy, hence your popping, sluggish tranny, no windows, etc, etc.
New alternator should do the trick but it also sounds like you hurt the battery as well. Keep an eye on it. When an alternator goes, the battery is usually not to far behind it.
Posted by Mike2001SS (Member # 2088) on :
The low voltage was the trouble with the way it was running so all you need is a alternator and get the battery to stay up.
Posted by danss98 (Member # 1994) on :
The only thing I would add is having each cell of the battery tested with a hydrometer. I had similar problems awhile back, battery tested fine but when they checked the cells with hydrometer it had a dead cell. It was a Diehard.
Posted by DaddySS (Member # 848) on :
Yes, the low voltage will cause all the other stuff. Since you were "running the car - be sure you didn't throw the alt belt. I don't know whether that car has a repalceable voltage regulator in the alternator or if it's all one unit, but if it's not the belt, it's probably one of those.
Posted by jimb0 (Member # 176) on :
When I started the car yesterday, I measured across the battery with a voltmeter and read about 12 volts, which was what the voltmeter in the car was showing. It went down from there. The SES light never came on, and the computer didn't throw any codes. The serpentine belt is good and all the connections look good. The battery terminals are clean, and the grounds appear sound. I'm checking out alternator prices, but I've been warned by at least a half dozen people to stay away from the auto parts house units. The auto electric houses will warranty the alternator (or whatever parts you buy from them), but you have to let them do the installation. My Formula is pretty pristine (less than 16K miles on the odometer), so I'm not going to put a junk part in it. I am a firm believer that you get what you pay for, so if it costs more to get a quality part, so be it. After all, the car is going on 15 years old, and the only thing I've replaced is the battery, the tires, and the power antenna.
Sure can't complain about that... Posted by 2002Z4CSS (Member # 1393) on :
You have a charging system problem. At idle with all accessories off, there should be around 13.5v to 14.5v at the battery. With all of the accessories on and just off idle, you should see more than 12v. The electronic body modules in the car are self protected and will shut down when the system voltage is too high or too low. My son's 1979 Camaro had a simular problem the other day at the track. His battery went dead and the ignition was breaking up.
Posted by Xsta Z 28 (Member # 740) on :
Alternator is toast, and the battery will be dead soon too . . . .
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