2002 surging when braking at lights.

[Rodles]

My 2002 base has had a history of surging when I brake approaching lights or slowed traffic. Very dangerous and revving up to 5,000 rpm when I got it into neutral. Had the dealer check the vacuum system and no problems found. The problem turned out to be a bad battery - evidently the computer is non functional unless it is getting the full 12 volts.

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[biddle]

My 2002 base has had a history of surging when I brake approaching lights or slowed traffic. Very dangerous and revving up to 5,000 rpm when I got it into neutral. Had the dealer check the vacuum system and no problems found. The problem turned out to be a bad battery - evidently the computer is non functional unless it is getting the full 12 volts.

What was the date on the battery? I try to warn People against waiting until the battery totally dies to replace.

 

[medurham]

Huh, interesting, we’ve had our 2002 for 2 months now, the only surging happened after sitting at the paint shop for a week, I had pulled out into a center merge lane and there were a few surges but it settled down. I guess I should see how old the battery is since we are heading into colder months.

 

[Bond007]

Many people inadvertently put their foot on the brake and accelerator at the same time. You need to be careful as they are close together.

 

[medurham]

We are new to the car so that certainly is a possibility as checking the battery it is a new Motorcraft.

 

[Matteo2002]

Many people inadvertently put their foot on the brake and accelerator at the same time. You need to be careful as they are close together.

Agreed...I've done it more than once. Those pedals are almost "dangerously" too close together for my men's size 12 foot.

 

[Frankie the Fink]

The "double pedal push" gets my vote. Most modern car electronics have voltage regulators in key circuits (heck, most old cars do too). And most cars operate on closer to 14V when running and the alternator is working.. 12V is the ambient battery electrical potential.

 

[Many Cars]

Check your AC refrigerant charge. If your AC or defrost is turned on and your AC charge is too low, the AC compressor will engage momentarily and then disengage. This cycle will continue indefinitely. When the compressor starts, the engine idle is boosted. When the compressor stops, the engine idle is lowered. The easy check is to let the engine idle with both the AC and defroster turned off. If the surging disappears, you have your diagnosis.

 

[56special]

What was the date on the battery? I try to warn People against waiting until the battery totally dies to replace.

@biddle, Do you have a battery recommendation?

 

[edward301]

One other thought is the idle control valve, not sure it can rev up to that high of an RPM,
but it can add a thousand RPM or so.

 

[Matteo2002]

@biddle, Do you have a battery recommendation?

Yes...I just purchased a Motorcraft BXT-66-750. It has the proper vent tube connection at the top. You don't want to install a battery that does not vent to the outside as gasses can build causing corrosion and a potential explosive situation, especially while connecting and disconnecting trickle chargers.