Bad Battery = Funky Performance ???
Thread Starter
Teching In
Joined: Aug 2004
Posts: 28
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Bad Battery = Funky Performance ??? I have a 1998 Pontiac Trans Am Convertible, with about 73000 miles on it. Only mods are a set of SLP 1.85 rockers and SLP Ram Air Kit/Lid. I bought the car used and have only had it a few months.
I had a cell start going bad in my battery. It got to the point that it registered 8-9 volts on the meter before starting the car but the car would still start. I could get the battery to charge up most of the way with my trickle charger, but after running the car for 5 minutes, it would be back to drained...
The funky part started recently, that when you would start the car, it would rev up to 2000 rpms instead of the normal 800-1000rpm. It did this several times, and then the engine wanted to run at 1500 rpm without pressing on the accelerator while the car was in gear.
This is my pleasure car not my daily driver, so I only drove it a couple times like this, and then yesterday, I got a brand new battery. The RPM Funkyness stopped immediately, so I feel confident the problem was fixed, but the oddest thing is that the car feels about twice as peppy as it did before the new battery. The car had seemed a little sluggish since the initial problem with the battery, but really didn't think much about it until I drove it with the new battery and could feel the pull again on accelleration.
Any comments as to why the car would behave this way would be welcome !!!
Thanks,
Rob
I had a cell start going bad in my battery. It got to the point that it registered 8-9 volts on the meter before starting the car but the car would still start. I could get the battery to charge up most of the way with my trickle charger, but after running the car for 5 minutes, it would be back to drained...
The funky part started recently, that when you would start the car, it would rev up to 2000 rpms instead of the normal 800-1000rpm. It did this several times, and then the engine wanted to run at 1500 rpm without pressing on the accelerator while the car was in gear.
This is my pleasure car not my daily driver, so I only drove it a couple times like this, and then yesterday, I got a brand new battery. The RPM Funkyness stopped immediately, so I feel confident the problem was fixed, but the oddest thing is that the car feels about twice as peppy as it did before the new battery. The car had seemed a little sluggish since the initial problem with the battery, but really didn't think much about it until I drove it with the new battery and could feel the pull again on accelleration.
Any comments as to why the car would behave this way would be welcome !!!
Thanks,
Rob
12 Second Club
Joined: May 2002
Posts: 262
Likes: 1
From: Holiday, Fl.
Interesting! I just put a new batt. in my SS a few weeks ago. It had been starting real slow for two weeks before that, so I knew it was going. If I revved it to about 2000-2500 for 20 sec. or so before I shut it off it would crank faster, but never noticed any of what you describe. 
TECH Regular
Joined: Sep 2004
Posts: 404
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From: Raleigh, NC
Robtest- Your car was simply trying to keep itself alive. It knew the battery was extremely discharged, so it ran the idle up so the altenator could produce higher output. Discharged batteries affect all kinds of things. Computer increases ignition dwell, longer injector pulse widths, increased idle, ...
TECH Resident
Joined: Jan 2002
Posts: 828
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From: dallas,tx.
.....you might wanna check your charging system out to make sure you have no problems in that arena.
When I was turning a wrench for a living I came across a vehicle, toyota I believe, that was fuel injected. The electrical system had to have 11.6 volts, period, or the car simplye would not run. So undervoltage situations do all kinds of wierd **** to stuff like starters, fuel injectors, fuel pumps, etc.
My corvette runs right at 14 volts when the car is running. 20 years ago I would have thought that too high, but it seems to like it there so I'm not too concerned at this point.
I'd simpley suggest making sure your alternater is up to snuff and doing what it's supposed to so you don't wind up replacing it along with another battery and possibly starter this winter.
Low volts = high amp draw which burns motors up real fast.
good luck.
When I was turning a wrench for a living I came across a vehicle, toyota I believe, that was fuel injected. The electrical system had to have 11.6 volts, period, or the car simplye would not run. So undervoltage situations do all kinds of wierd **** to stuff like starters, fuel injectors, fuel pumps, etc.
My corvette runs right at 14 volts when the car is running. 20 years ago I would have thought that too high, but it seems to like it there so I'm not too concerned at this point.
I'd simpley suggest making sure your alternater is up to snuff and doing what it's supposed to so you don't wind up replacing it along with another battery and possibly starter this winter.
Low volts = high amp draw which burns motors up real fast.
good luck.
