'98 Taurus AT question

[K-Man]

After disconnecting the battery for safety while (finally) installing an aftermarket stereo head unit (radio, cassette, CD), the Taurus seems to slow down much more rapidly during deceleration (taking foot off loud pedal) or shutting off cruise control than before.

In fact, before it would readily "coast" under deceleration or adjusting cruise control; deceleration was much more gradual. The deceleration now is striking and took me by surprise today when I had the car on the highway for the first time since the stereo installation.

I assume that this is probably from some setting in the ECU that was changed when the battery was disconnected and now must be "relearned". The car otherwise performs and accelerates as well as before, and I don't think the transaxle has any mechanical issues. But is this change anything I should worry about? Is there some related dealer reflash that this car needs since the battery disconnection?

 

[punisher]

Always a good idea to reset idle strategy after disconnecting the battery. I have run into strange symptoms on certain vehicles after minor work requiring battery disconnection.

 

[mstrjon32]

I don't think an idle re-learn would cause such symptoms, but it can't hurt anyway. Are you sure you didn't mess with any shift linkages or what not while installing that stereo? It sounds to me like you're driving around in 3rd instead of 4th.

 

[K-Man]

Did not mess with anything to do with shift linkages. Engine rpm is ~ 2400 rpm as usual at around 60 mph, so the transaxle is in 4th gear. (With O/D off and the transaxle kept in 3d gear, it would be at over 4000 rpm at the same road speed.)

All work was in the rear of the car to connect a new purpose-made wiring harness to the existing radio connectors and then in the hole in the dash where the original radio and HVAC controls were mounted.

The problem seems to be slowly getting better, but I'm keeping a close eye on it. I'm positive now that disconnecting the battery reset something that now causes this more abrupt deceleration. It's especially noticeable when going down a grade with the cruise control on and the car reduces speed to compensate, but again it seems to be starting to get better.

 

[oilboy123]

It is normal. I have had my batt disconnected a bunch of times as well as my Daughters 96 Taurus.
There is a TSB for the concern of it feeling like it freewheels down hills. I don't know what the TSB# is.

I would not worry about it. The PCM should go thru the drive cycles and it should revert to normal.

 

[oilboy123]

Forgot to mention I did my stereo install about 2001 and helped my Daughter do hers at Christmas.

Fun are they not?

 

[K-Man]

Yep, stereo installation is fun. Especially after troubleshooting electrical problems after the installation (traced to one of the new connectors, had a pin pushed out). But all ended well and the new head unit works great.

 

[K-Man]

Forgot to mention: the deceleration problem is definitely getting better.

Funny side note: I could not find any straight petroleum jelly to put on the battery terminals after cleaning them before reconnecting the battery, so I made do with a little triple antibiotic ointment. It's mostly mineral oil and petroleum jelly anyway, and now I don't have to worry about the battery getting infected. (Also used those anticorrosion felt donuts too.)

 

[shoz123]

On my car I tune it for rather drastic deceleration. There are tables in the PCM programming I manipulate called Coasting Fuel Shut Off where the fuel injectors are actually turned off and the Idle Air Control valve is set to a minimum to get the maximum amount of deceleration. I also keep the torque converter locked for even more engine braking.

This is done for road racing when manually down shifting.