SemiSmartGuy

2011 Mustang, about 4500 miles on it. This has now happened twice...

Car has been sitting for about 45 minutes, I get in and roll out to a main street and then just jump on it. Car accelerates nice and hard, everything is good and then all of a sudden it acts as though the ABS engaged. Thumping noise, almost like a tire is off the wheel, I brake but the pedal doesn't feel right, it pushing back. This is really weird! I pull over, check it out, everything looks fine. Nothing is loose, no smells or anything. I get back in and pull back onto the road and it is still grabbing and acting strange. One more stop to check everything and than back to the road, now it's back to normal, drives fine. I can't think of anything other than ABS that could cause this (at no time did the rear tires break loose), I can't see TC causing this because it's all in the front end.

This is the second time it has happened. Much worse this time. Ford dealers have no clue (I took it in the first time, they found nothing). I'll be taking it in Monday but I'm just wondering if anybody else has had anything like this happen.

Again, both times the car was warm but had been sitting for 45 minutes or so, drive for just a minute or so to get to a main street and then floor it. The car had just shifted from low (automatic) when this event occurred.

Anybody????

67mustang302

Does it only happen when you're hard in the throttle?

If I'm reading right it starts when you get hard in the throttle, but then even after when driving normally for a bit it seems to still be engaged?

A couple things, the TC could engage the front. If you accelerate hard while turning and have the right slip angle and start to understeer the car, the wheel speed sensors may detect different front wheel speeds as a result and the TC will engage the ABS valve.

Also, it could be a sticky brake caliper in the front, ABS engages and then one brake doesn't back off correctly, so there's a constant difference in wheel speed and it keeps the ABS engaged.

Could be an ABS valve or wheel speed sensor issue, or even something with the TC/ABS software or wiring.

Honestly though, I wouldn't even drive it like that if you suspect something involving the ABS system. Have the dealer tow it. If you have the ABS come on in the front while making a turn in traffic, you can understeer right into another car, or a telephone pole etc.

Also, are there any bulges in the tire? How does the tread wear look?

SemiSmartGuy

Yes, only when under hard acceleration. Car is going dead straight and the brake pedal is not being touched. I'm an old street racer and have never been a two-foot driver. It just engages on its own, for no reason.

It is severe enough to be a little unsettling, no doubt about that. However, this car is pure...really pure in all circumstances. Just twice, in similar situations, has it exhibited this strange behavior. I have cornered hard many times and I had to brake pretty hard one time, she has been true blue in every circumstance, could not ask for more really (it's a premium with one of the handling upgrades and one of the suspension upgrades and really a pleasure to drive).

67mustang302

So only when under hard accel? As soon as you let off it stops?

Does it do it when you turn the t/c off?

SemiSmartGuy

No, it does not stop when I let off...once it starts doing it, I just have to wait it out. I pull over almost immediately and it keeps doing it as I'm pulling to a stop. This second time it happened it lasted longer, took a couple of stops for it to go away.

I have not tried driving with TC off...but I will if the dealer doesn't find anything this time. I hate this being intermittent, Ford won't do anything, they won't change a sensor or try anything because any repair counts against the lemon-law counter. Nice law and everything, but now they won't try anything. I'm asking the service manager...so if this happens while you're driving it, what would you fix? What would you try? Well...try that now, I'm telling you it happened! Waste of time, they won't "try" anything.

67mustang302

And the car is bone stock, nothing was changed?

If your state has a better business bureau or something similar and they refuse to fix it, you could try to get a resolution through them.

Chipster

Same thing just happened to me this morning. 2013 GT. Had to pull over a wait it out. Very weird. I will disable the Traction Controll and Advanced Trac if it happens again to see if that clears it.

Have you resolved it?

SemiSmartGuy

The bad news...No I have not resolved it. The good news is it has only happened once in the last several months. Still very disconcerting, but it is rare and only happens at low speeds (for whatever reason). Good thing, with the BAMA tune and the new .355 gears that little V6 is twitchy! :-)

Report it for sure and maybe a report to the NHTSA (they do recalls). Your dealer will probably tell you that if they can't duplicate the event, they won't record it. That's crap, but that's what they do (every reported problem goes against the "lemon law" record for your vehicle, so they won't record it). I'm sure it's the same for all manufactures. The lemon law is supposed to protect us but it actually just causes the dealers to be less helpful.

I will look into reporting it to the NHTSA too, we don't have any other options as far as I can figure.

Good luck,
mike

Chipster

Good info. It's only happened to be the one time, and it was after the first real hard cold front. Let's see what happens when the next cold front hits.