Car jerks when slowing to a stop

[powertorque]

Hi,

I'm currently driving a e46 325 cabrio (2002). Noticed that the car jerks whenever it is slowing down to stop. The jerk is brief but strong enough to be felt. A sound could be heard coming from the rear, like from the undercarriage. Was told by someone it's got something to do with the ECU programming. Anyone has a similar experience before and can advise what could be wrong? Intend to bring to PML for a check tomorrow but would like to hear from fellow forumers first.

Thanks

 

[ryan]

Hi,

I'm currently driving a e46 325 cabrio (2002). Noticed that the car jerks whenever it is slowing down to stop. The jerk is brief but strong enough to be felt. A sound could be heard coming from the rear, like from the undercarriage. Was told by someone it's got something to do with the ECU programming. Anyone has a similar experience before and can advise what could be wrong? Intend to bring to PML for a check tomorrow but would like to hear from fellow forumers first.

Thanks

Most likely it could be due to your rear transmission mountings being worn out.

ECU controls the engine mapping etc, and it's an electrical component, it's almost impossible that it's the ECU! Your problem is a physical component.

I had this problem and it was more like a soft "thud" sound when my ex- car downshifted from 3 to 2.

Is that it?

 

[powertorque]

Hi,

I'm currently driving a e46 325 cabrio (2002). Noticed that the car jerks whenever it is slowing down to stop. The jerk is brief but strong enough to be felt. A sound could be heard coming from the rear, like from the undercarriage. Was told by someone it's got something to do with the ECU programming. Anyone has a similar experience before and can advise what could be wrong? Intend to bring to PML for a check tomorrow but would like to hear from fellow forumers first.

Thanks

Most likely it could be due to your rear transmission mountings being worn out.

ECU controls the engine mapping etc, and it's an electrical component, it's almost impossible that it's the ECU! Your problem is a physical component.

I had this problem and it was more like a soft "thud" sound when my ex- car downshifted from 3 to 2.

Is that it?

Hi ryan,

yes, it is a thud sound when downshifting. I read in another post titled "Unique problems on E39" in this forum that it's got to do with programming.....maybe there're more than one cause to the problem.....anyway, is it costly to replace the rear trans mounting?

Thanks!

 

[russo]

Don't panic. Its the ECU. Just go down pml, get them to recode the ECU to the latest software and your 'clonk' when downshifting will be very much reduced.

 

[powertorque]

Sent car to PML last week and they did a reprogramming. Seemed to do the trick. No more "clonk" sound and jerk. Yipppeeee!!

 

[ryan]

Sent car to PML last week and they did a reprogramming. Seemed to do the trick. No more "clonk" sound and jerk. Yipppeeee!!

Congrats on the fix and ...do you have any ideas how this is related to the ECU?

Russo, could you explain? Haha..i would really like to know. No ill feelings involved.

Cheers!

 

[powertorque]

Russo,

Yes, can you please explain how the old software caused the car to go "clonk"? I'm very curious and hope to learn something as well.

 

[eaurouge_spa]

powertorque,

Its to do with the EGS or electronic gearshift software. Previously, when coming to a stop, the car downshifts from fifth directly to second gear rather abruptly, thus you get that "clonk". With the new software, it goes from fifth to third to second gear, thus smoothening the downshift.

 

[powertorque]

eaurouge_spa,

Thanks for the explanation!
Fifth to second? Gosh, how could anyone write a program like that and the bug not discovered before rollout!?!?!
I wonder if any damage is done to the mechanical parts of the car since this problem is rectified only recently.....the CSA at PML did ask me to book an appt to check the rear transmission (?? no sure if i'm using the right term here). I was thinking of not doing it since the problem appears to be resolved.

 

[0000]

Re: Car jerks when slowing to a stop

tink i have this same problem too.. Can u guys tell me how much it cost for the software upgrade? Mine's a 92 320 auto e36 coupe

 

[Racebred]

Re: Car jerks when slowing to a stop

while on throttle-off deceleration, the new EGS also hangs on a higher gear (like 5th gear) longer than usual so there isnt any unnecessary downshifts (hence no clonks) if you should be coming to a complete stop. The downshift is done much later when engine+transmission+wheel speeds are much lower.

 

[beem]

Re: Car jerks when slowing to a stop

I have this slight clonk sound but after the EGS programming, its not that often but sometimes still got lah, but very much softer and infrequent...HOW?

So...what's with the transmission bushings?