New battery cures clatter?

I’ve owned a 99 Taurus for about 4 1/2 years. It’s always had a clatter acceleration. Like the kind you get with bad fuel, or out of whack timing. I’ve been thru the car over and over, and had mechanics look at it. Only answer I could get was “use premium gas, or a better gas station”. Premium did help a bit, but my car doesn’t need it. About a week ago, my battery bit the dust. Since I replaced it, the clatter is gone. Completely! Also fuel mileage slightly improved, and the car seems to want to “go” now! No hesitation. Been thru a few fill ups, so it’s not “better” fuel. I’m having a hard time believing that just a new battery fixed it! Could it really have? And how?

It sounds like you have “pining” or pre-ignition in your engine. Your old battery probably did not cause the pinging, but the engine timing may have been out and the new battery may have cause the system to reset itself.

Disconnecting the battery probably changed something. Possibly your monitors are relearning everything and are not yet in ready status. Maybe you went on the highway and accelerated hard and blew the carbon out of your cylinders.

When you remove the battery it causes the engine computer to reboot in some cars. It sets all the engine control parameters back to what they were when the car was new. Over time these parameters change b/c of gunk accumulating in the throttle body and other changes happening to the engine due to age and use. So if this theory is correct the pinging may return over the course of a few weeks or months of driving. Two common causes of pinging are spark plug gaps too wide, and the knock sensor on the fritz.

Bad/poor batteries have been related to many curious conditions, I chalk this up as another one, but it would not have been on the radar given your symptoms. The engine learning reset is also a possibility, but that would not be on the top ten list of cures either. could be a poor battery and poor connection or low voltage to a sensor combo! Thanks for the info!

Here’s the twist though. I also thought it was a timing, or fuel air issue. So about 3 months ago I decided to disconnect the battery long enough to kill any memory back up. So that the computer would have to re learn timing, fuel, and air readings. I completely disconnected the battery. Ground and positive. Not touching anything. It sat for 3 days, and didn’t change anything. Still clattered. When I changed out the battery, it was only disconnected for a few minutes…So…I’m still confused. Also, it’s still running awesome!

Modern computerized cars needs a healthy battery and a strong 12VDC to run properly. Disconnecting the battery that’s not up to par will fix nothing. You found that out.

The electronics of computers (etc.) runs on 5 (or less) volts (the lower the voltage, the less power needed). One powers them by applying an input voltage of 7.5 or more volts to a voltage regulator (not the car’s regulator). As long as the input voltage stays above 7.5 and below the maximum the regulator can tolerate (typically 37 for a 5 V supply) the computer works the same.

I think what you did OP was a good experiment and proved the clatter wasn’t caused by resetting the computer when the battery got replaced. And it seems unlikely clatter would be caused by a slightly discharged battery. The voltage available to run the car when the engine is running is well over the normal 12.5 volt battery voltage, usually 13.6 volts or more.

So it remains a mystery why changing the battery got rid of whatever was causing the clattering.

The only thing I can come up with is the battery terminals were corroded, and that was causing the ECM (computer) to hick-up when a large current spike went through the battery. Either that or the old battery was loading down the alternator and making it put out voltage spikes, which was confusing the ECM. I doubt the above theory is the whole story though, there must be something missing not yet discovered.

I suggest you have the alternator checked to see if it is generating excessive ripple voltage due to some bad diodes inside it. The new battery may have lowered the excessive output level so the DC voltage runs a little cleaner, less noise riding on the DC.