jerky behaviour

drb11

I am having a serious issue. Hope somebody can help me out.
On the following scenario:
1. If I don't press gas and brakes and let car roll to a stop, it drops speed abrupty (could feel resistance) and then jerks several times to stop. Although this is not noticeable in speedometer, but very nicely felt.

2. Above jerks happens if I lightly press the brakes and try to stop.

3. Lot of brake dust in front wheel rims but none in back wheels.

4. Everyday morning when I reverse the car for the first time to work, I hear a very squealing noise and disappears. WIll not happen rest of the day. Noise happens only during reverse, first time of day.

Today I took to dealer, he said brake pads collecting powder and interfering with brake drums, causing some resistance. He asked me brake (sudden) few times and also use hand brake to clear up brake pads and drum. This has to be done once in 2 weeks or so to keep everything clean.

It didn't help much.

PLease help.

drb

dclurker

Can't help you with the first two. Number 3 is normal because the front brakes do most of the work. Number 4 is a common trait with Mazda 5s (including my own). I don't know of any cure. If it really embarrases you, I suppose you could back into your parking place each night

vicenac

Number one is caused by the car downshifting into the first gear hence engine braking. Try shifting manually to reproduce the effect. Look at the RPM.
Same for number two.
Now engine control is not the best in the world at Mazda. When hot outside you may notice the engine changing idle speeds between almost chocked and enthusiastic. At low speeds it can cause some jerks. Watch out when maneuvering the supermarket parking lot.

larry8061

How about some details?

A: Is this a manual or an automatic?

B: How many miles?

Let's start there.....

Larry

wwest

1. You're describing the coastdown fuel cut technique now being used to improve FE. During throttle off coastdown periods the engine fuel flow is cut off COMPLETELY and the roadspeed is then used to prevent the engine from "stalling". Given a high enough "entry" speed the transaxle is downshifted again and again as roadspeed declines and then once you reach a roadspeed too low to sustain engine RPM above idle the trnasaxle is upshifted. Now as you come to a final FULL stop the transaxle will downshift into first.