Uncommanded Acceleration
Discussion
Very interesting topic on Aston Owners.com
https://astonowners.com/Forum?p=post%2Funcommanded...
Looks like a defective wheel bearing could make the cars accelerate uncontrollably!!!
https://astonowners.com/Forum?p=post%2Funcommanded...
Looks like a defective wheel bearing could make the cars accelerate uncontrollably!!!
Already being discussed in this thread
https://www.pistonheads.com/gassing/topic.asp?h=0&...
DAE have even chipped in
By way of example example, any advice on PH is freely available to anyone with an internet connection, but if you want to post then you need to join, which is fair. Same with SwedeSpeed, Sixspeedonline, Aston36, Redpants, etc., etc.
https://www.pistonheads.com/gassing/topic.asp?h=0&...
DAE have even chipped in
paulrog1 said:
You don't need to pay to go on the forum, just need to sign up.
I've never paid any money.
Not the point. Information is the new oil - any community-minded group would make this sort of information freely available. I've never paid any money.
By way of example example, any advice on PH is freely available to anyone with an internet connection, but if you want to post then you need to join, which is fair. Same with SwedeSpeed, Sixspeedonline, Aston36, Redpants, etc., etc.
Same article popped up on Reddit, except there they transcribed into the free forum..
https://www.reddit.com/r/AstonMartin/s/Vm5EEYbx4Q
I had a strange issue earlier in the year on a Euro road trip…after long runs on the m/way and then hitting traffic / queues, the car started to creep forward at standstill requiring SIGNIFICANTLY more brake pressure than the normal ‘barely resting’ foot on the brake. At the time i thought it was related to brake fluid overheating as i previously had a seized piston causing a cyclical noise (audible at low speeds from the front right / drivers wheel) and assumed there was heat transfer through the brake assembly into the fluid. However i checked the reservoir and there didn’t appear to be any cloudiness.
The noise issue (cyclical noise, sounds like creaking almost) is still there but despite the brake assembly and wheel hub being striped by AM, no underlying issue has ben found…..wondering if this ‘Reluctor ring’ could be the culprit…?
https://www.reddit.com/r/AstonMartin/s/Vm5EEYbx4Q
I had a strange issue earlier in the year on a Euro road trip…after long runs on the m/way and then hitting traffic / queues, the car started to creep forward at standstill requiring SIGNIFICANTLY more brake pressure than the normal ‘barely resting’ foot on the brake. At the time i thought it was related to brake fluid overheating as i previously had a seized piston causing a cyclical noise (audible at low speeds from the front right / drivers wheel) and assumed there was heat transfer through the brake assembly into the fluid. However i checked the reservoir and there didn’t appear to be any cloudiness.
The noise issue (cyclical noise, sounds like creaking almost) is still there but despite the brake assembly and wheel hub being striped by AM, no underlying issue has ben found…..wondering if this ‘Reluctor ring’ could be the culprit…?
Aml21s said:
I tried to register to the forum each page mentioned PayPal even if you choose free membership it's so complex and confusing I couldn't finish. I m not surprised it's screw like this
Maybe Paulrog1 can help, he didn't seem to have a problem - I have paid to join as it is an excellent community. Don't think AMOC allows free access to their forums .
I recently bought a 2008 AM V8V 4.7L SS1 which had a decent PPI (Nothing major, just some wear and tear) with 37k miles. The previous owner said the clutch was changed at about 35k miles. So far it rides pretty well, except the car seems to like to jerk forward in 1st gear when the car is cold and hasn't sufficiently warmed up (Transmission oil?) between 6-10 km/hr at under 1k rpm.Keeping the revs at about 1k rpm or foot depressed on the brakes does seem to prevent this.
However, I had a scary dangerous sudden unintended acceleration (SUA) happen twice today. Once as I was heading out from the car park and another as I was slowing into a junction. I did the clutch learn as usual on start up, let the engine warm up for couple of mins before heading out. As I was slowing down at slow speed heading into a bend, the car suddenly decided it wanted to accelerate. Thankfully, my foot was already on the brake as this happened as I was slowing down towards a bend. The car just accelerated forward, and the harder I stepped on the brakes, the stronger it accelerated. This wasn't a gentle acceleration, it was fighting against the brakes and moved forward even when my foot on the brakes. I had to put my weight on brake pedal to fight to keep the car stationary until the car stalled. It wasn't pleasant!!
I was just thankful my foot was already on the brakes and could react in time. I could have slammed into other cars in the car park or into a wall or into a pedestrian at the zebra crossing if I didn't react in time. Drove really carefully for the rest of the trip especially as I'm slowing down on 1st gear, putting the car into N during idle. Found the article on Reddit and I'm astonished how AM hasn't put out a circular at on this, cars have been recalled for much lesser. I'm not even sure the local AM agent is aware of this issue here in Singapore, and I don't wanna be spending $$$ while they are learning on the job at my expense.
Hopefully, changing the wheel bearing sensors will solve the issue. I'll report back.
However, I had a scary dangerous sudden unintended acceleration (SUA) happen twice today. Once as I was heading out from the car park and another as I was slowing into a junction. I did the clutch learn as usual on start up, let the engine warm up for couple of mins before heading out. As I was slowing down at slow speed heading into a bend, the car suddenly decided it wanted to accelerate. Thankfully, my foot was already on the brake as this happened as I was slowing down towards a bend. The car just accelerated forward, and the harder I stepped on the brakes, the stronger it accelerated. This wasn't a gentle acceleration, it was fighting against the brakes and moved forward even when my foot on the brakes. I had to put my weight on brake pedal to fight to keep the car stationary until the car stalled. It wasn't pleasant!!
I was just thankful my foot was already on the brakes and could react in time. I could have slammed into other cars in the car park or into a wall or into a pedestrian at the zebra crossing if I didn't react in time. Drove really carefully for the rest of the trip especially as I'm slowing down on 1st gear, putting the car into N during idle. Found the article on Reddit and I'm astonished how AM hasn't put out a circular at on this, cars have been recalled for much lesser. I'm not even sure the local AM agent is aware of this issue here in Singapore, and I don't wanna be spending $$$ while they are learning on the job at my expense.
Hopefully, changing the wheel bearing sensors will solve the issue. I'll report back.
Very scary.
The reason why the car starts fighting you is because the car has an incorrect input from the ABS sensors, the car wants to keep all 4 wheels rotating the same but the car thinks one wheel is rotating slower so it increases engine speed because of broken/faulty wheel bearing rings.
I'm very surprised because I didn't think the brake control module would be programmed to do this, they should failsafe to limp mode and put the ABS light on the dash.
You may have issues with your wheel bearings.
Shown below is a hub that had uncommanded acceleration with broken bearing rings.
My car is currently in pieces on my 2 post lift, I replaced the rear bearings a few years ago but I've noticed the front bearings have corrosion on them so when putting my car together I'll wire brush them.
AM defo will not want to redesign the wheel hubs and replace them all on a safety recall, maybe an updated software patch to the brake module might fix this, fingers crossed nobody gets hurt.
The reason why the car starts fighting you is because the car has an incorrect input from the ABS sensors, the car wants to keep all 4 wheels rotating the same but the car thinks one wheel is rotating slower so it increases engine speed because of broken/faulty wheel bearing rings.
I'm very surprised because I didn't think the brake control module would be programmed to do this, they should failsafe to limp mode and put the ABS light on the dash.
You may have issues with your wheel bearings.
Shown below is a hub that had uncommanded acceleration with broken bearing rings.
My car is currently in pieces on my 2 post lift, I replaced the rear bearings a few years ago but I've noticed the front bearings have corrosion on them so when putting my car together I'll wire brush them.
AM defo will not want to redesign the wheel hubs and replace them all on a safety recall, maybe an updated software patch to the brake module might fix this, fingers crossed nobody gets hurt.
Edited by paulrog1 on Wednesday 18th February 10:35
Edited by paulrog1 on Wednesday 18th February 10:37
paulrog1 said:
Very scary.
The reason why the car starts fighting you is because the car has an incorrect input from the ABS sensors, the car wants to keep all 4 wheels rotating the same but the car thinks one wheel is rotating slower so it increases engine speed because of broken/faulty wheel bearing rings.
I'm very surprised because I didn't think the brake control module would be programmed to do this, they should failsafe to limp mode and put the ABS light on the dash.
You may have issues with your wheel bearings.
Shown below is a hub that had uncommanded acceleration with broken bearing rings.
My car is currently in pieces on my 2 post lift, I replaced the rear bearings a few years ago but I've noticed the front bearings have corrosion on them so when putting my car together I'll wire brush them.
AM defo will not want to redesign the wheel hubs and replace them all on a safety recall, maybe an updated software patch to the brake module might fix this, fingers crossed nobody gets hurt.
IMO there is no reason to redesign the hub, as bearings with in-built magnetic reluctor rings seem fairly common, particularly on Fords (what a surprise). The issue seems to be how the car is reacting to a signal outside of the normal parameters.The reason why the car starts fighting you is because the car has an incorrect input from the ABS sensors, the car wants to keep all 4 wheels rotating the same but the car thinks one wheel is rotating slower so it increases engine speed because of broken/faulty wheel bearing rings.
I'm very surprised because I didn't think the brake control module would be programmed to do this, they should failsafe to limp mode and put the ABS light on the dash.
You may have issues with your wheel bearings.
Shown below is a hub that had uncommanded acceleration with broken bearing rings.
My car is currently in pieces on my 2 post lift, I replaced the rear bearings a few years ago but I've noticed the front bearings have corrosion on them so when putting my car together I'll wire brush them.
AM defo will not want to redesign the wheel hubs and replace them all on a safety recall, maybe an updated software patch to the brake module might fix this, fingers crossed nobody gets hurt.
I don't think the ABS system would ever demand more power, so my uneducated guess is the lack of or slow signal from one wheel is messing with the stability system. Would I be right in guessing that the bearings with the broken reluctor rings are in the rear hubs?
Another possibility (that happened to me). I had check braked when in cruise - the car slowed a little, then accelerated. I braked and it did it again. Very disconcerting and disorientating. I later realised the the cruise control had not disengaged on pressing the brake pedal, and thus the car was accelerating back up to the cruise setting. I eventually disengaged cruise manually, but it was a close call with a slow moving artic.Couldn't find anything amis with the brake pedal switch, but changed it anyway.
Edited by Ryan john on Wednesday 18th February 17:11
Probably very unlikely, but if we do ever encounter these circumstances, hard braking would be the natural response, but would flicking the glass key out, stop the engine?
If so, then that is something to keep in our brains.
There is often not time to start thinking when any emergency occurs, so having pre-thought actions ready can be important.
Thanks for the replies lads.. If anything, it's always safer to brake or slow down gradually than to force an acceleration in any case, it should not work against that principle. In a way, this reminds me somewhat about the Boeing 787 Max anti stall feature where it overrides the pilots and points the nose down until it eventually crashes..
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