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Challenger Lost Power and Brake Pedal Went to the Floor

11K views 24 replies 13 participants last post by  KDodge75 
#1 ·
I remember reading a few threads a while back about challengers stalling. I found and read a few but haven't found any answers that fit.

I have a 2011 R/T Classic Green with Envy. I had just finished going down a 2 mile long windy road I've been on several times before. I had about 1/8 of a tank of gas. When I got to the end, I was braking normally then ran through some potholes. All of a sudden, I lost power and the brake pedal went to the floor. Luckily I didn't roll out into traffic. I pumped the brakes a few times but they still went to the floor. All of a sudden, RPMs came back up and the pedal went back to normal position. I have just over 30,000 miles on it and have never had this happen before.

I'm not sure if this was a combination of the low gas, windy road and potholes or just low gas coupled with windy road caused air in the fuel line.

Any ideas from anyone?
 
#2 ·
Have you bled the brakes? The fluid needs to be flushed/bled every 2 years. It can (make that will) collect moisture and under severe (prolonged) braking the brake fluid can get hot enough to boil. (The presence of water lowers the fluid's boiling point.) This boiling of the brake fluid can result in spongy brakes or even a loss of braking. Most often this is experienced with someone driving on a road course but that winding road may have been close enough to cause the brakes to get hot and the behavior to occur.

(I can tell you with my Boxster experience which has a hydraulic system that has the clutch and brake systems sharing fluid that even after just 2.5 years of "neglect" (failure to bleed the brake/clutch system) the deteriorating fluid was affecting clutch behavior. After the brake and clutch systems were flushed and bled the clutch behavior was once again just fine. While at no time did I notice any braking issues I never pushed the brakes that much, got them hot, but I'm convinced had I the brakes would have let me know the fluid was past its flush/bleed time.)
 
#3 ·
if you were down that low, you probably had fuel starvation and that killed the engine.

Once you depleted vacuum reserve, no more power assist. Brake pedal will travel much further and will require lot more pressure (you're trying to operate 4 disc brakes = lots of fluid displacement).

Once the engine was running, you once again had vacuum in the brake booster and it worked under power assist again.
 
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#4 ·
Did you get wheel hop when you went through the potholes? If you did, the antilock brakes may have kicked in and backed the brakes off trying to keep the wheels from locking. That would cause the loss of brakes. I have had this happen to me a few times with different cars on washboard country roads.
 
#6 ·
No but about a month ago, I had a box truck pull out into an intersection in front of me on a red. I had a green. The road was wet so there was so stopping. I hit the brakes hard and antilock kicked in. He stopped and I swerved hard left to avoid him then hard right to not hit the sign in the median. After than, my brake pedal was very low. Tried pumping the brakes with the car running but the problem was not resolved. I finally pumped the brakes several times with the engine off and they finally returned to normal height and firmness.
 
#5 · (Edited)
I forgot to mention I have an M6. Didn't do much braking, just downshifting before the curves. I have not flushed the brake fluid. The owner's manual makes no mention of brake fluid changes being necessary.

No wheel hop. Just the front tires hit the holes when I was almost fully stopped.

I'm leaning toward fuel starvation. Here's what I think happened. In the M6, fuel delivery turns off when you are in gear, not on the throttle and your RPMs drop below a certain level (1100 RPMs or so). It has a name but I can't recall what dodge calls it. I seem to recall that the problem occurred just a 1/2 second after I pushed in the clutch pedal. I think at that point, there was air in the fuel line just enough to where when fuel delivery turned back on but there was no fuel reaching the injectors. When fuel did finally reach, the engine fired back up and everything returned to normal. I filled it up with gas this evening and it took almost 18 gallons out of 19.5 gallon capacity so it was pretty low.

Another thing I have had happen is I've parked in my driveway with about the same fuel level and the next morning, I could not start it. I've had to grab the gas can from the garage and put about a gallon in it so I could start it.
 
#7 ·
I forgot to mention I have an M6. Didn't do much braking, just downshifting before the curves. I have not flushed the brake fluid. The owner's manual makes no mention of brake fluid changes being necessary.

...
Neither does mine, but it should be done either by mileage or time passed (30K/24 months) to ensure optimum brake performance the life of the car.

I’m sure it’s possible to go several years and 100K miles without replacing the brake fluid, but holy crap it sure would be ill-advised to do so, IMHO.

I have a Chiltons manual for 2005-2010 LX cars, and here’s what it recommends:
Font
 
#8 ·
Intelligent Deceleration Fuel Shut-Off (iDFSO) is the technology that turns off fuel flow when off the throttle and over a certain RPM. If you are ever off the throttle and slowing down somewhere just below the 1100 RPM mark you'll feel a surge and the car feels like it picks up speed just a bit. This is the fuel supply turning back on the the engine firing. I think the automatics also use the same technology.
 
#11 ·
I just has this happen again. Similar situation but full tank of fuel.

This time, I was traveling on a level road but I was accelerating purposely then had to brake a little harder than normal a the end of the road. Just as I hit the brake and pressed the clutch, I hit 2 pretty good holes in the road where they paved around small water cutoff access pipes and the brake went almost to the floor and lost power for a half second.

I can't find anything about these cars having inertia switches so I'm not sure what's causing it. It's really hard for me to avoid holes in the road as they've planned for about 10 years to expand the main road where my house is but still haven't started. Instead, they just keep patching the holes. The are supposed to finally start work soon.
 
#13 ·
I can't find anything about these cars having inertia switches so I'm not sure what's causing it.
There is, not sure where or how it works exactly, but there is such a safety system on these cars.

It kills the fuel pump and on the newer cars also unlocks the doors and turns on the 4-way flashers.




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#12 ·
I think you really need to get your brakes checked and change the fluid. It is an 8 year old car and you report having lost your brakes several times with the pedal going to the floor. It is really unwise to use the car until you solve the issue.
 
#16 ·
I believe your brake issue is related to the engine stall. when the engine stalls, or perhaps with the drive by wire opening the throttle during even a "stumble" (I am not sure of this) there is zero vacuum. the "power" in power brakes comes from a vacuum booster. When you have NO vacuum you have NO boost. I had a throttle get stuck once, years ago. I calmly switched off the engine but was surprised to fine I had nearly NO brakes. It took both feet to get it stopped. The issue was, at FULL THROTTLE, there was NO vacuum to boost the system. I do not think your issue as anything to do with the hydraulis side of your braking system.
 
#18 ·
I've had this happen a couple more times. Same sequence of events, braking, clutch in hit bump, pedal drops lose power but no stall. I've had a couple other strange electrical things happen as well. I've had a couple stalls for no apparent reason.

Today, after grabbing breakfast, I went to start the Challenger and power goes off then every second of so, you could hear clicking in the trunk and the dash lights would flicker. I'm stranded at the restaurant waiting for my wife to bring my truck to jump start it. I could get enough power to keep everything on but never could get enough juice to turn over the engine.

Drove a couple blocks down the road to the auto parts and picked up an AGM battery. So far, everything seems good since installing the new battery. I did hit some unavoidable potholes while braking on the way home with no issues.

Looks like the problem may have all been from a dying, 7 year old battery.
 
#19 ·
I have seen a loose post in an old/aging battery act up intermittently like that. Not a loose cable mind you, but the actual lead post in the battery case can start to detach from its mooring and act crazy on and off.

Not a common battery failure, but a remote possibility in old or mistreated batteries for sure.
 
#20 ·
I was researching Z28's last year and they have something called "Ice mode" might be a google search topic. Same thing your experiencing.


Funny but sad thing is they post im thinking of the young guy totaled his car on his own street in Miami Fl....ice mode.

I now I am a sour puss on here but Canbus on a car is the biggest mistake automakers ever ever made.

I would really think of pushing for a FCA buy back. I dont think they can fix the problem. They bought one of my siblings car back for shutting off in traffic and highway speeds.

Sorry If I had posted this here before.
 
#22 ·
5 years later that this is still happening. It's the ABS kicking in momentarily and when it does, the pedal stays almost to the floor. Happened today while pulling into a neighborhood where there was a 4" drop in pavement depth. I can usually get it to reset by turning off the vehicle and pumping the brakes but this time, I haven't had any luck. I don't think it's the master cylinder. I believe this is something with the ABS hydraulic unit. Looks like I have a project for tomorrow.
 
#23 ·
.... 😳

5 years later that this is still happening. It's the ABS kicking in momentarily and when it does, the pedal stays almost to the floor. Happened today while pulling into a neighborhood where there was a 4" drop in pavement depth. I can usually get it to reset by turning off the vehicle and pumping the brakes but this time, I haven't had any luck. I don't think it's the master cylinder. I believe this is something with the ABS hydraulic unit. Looks like I have a project for tomorrow.
... 😭
 
#25 ·
The original brake fluid tested out with 0% water content but was changed anyway even though I knew it wasn't going to make any difference. This issue has occurred even with fresh brake fluid. Between my last post in 2018 and now, this has occurred at least 50 times. Most of these occurrences are in a particular shopping center roadway where the pavement drops 3" about 30' from the stop sign. It's spaced just right to where I always hit the brake just a fraction of a second before the drop-off when approaching the intersection. This causes ABS to kick in every single time and every time, the pedal goes to the floor. Sometimes, I remember to lift my foot from the brake before the drop-off or I don't touch the brake until after. This keeps ABS from triggering since the brake is not being applied.

I did manage to get the brake pedal firmed up so we're good to go again until something triggers ABS again.

I've found several mentions of this same issue occurring in Chrysler vehicles and other makes and models that use hydraulic abs units from the same manufacturer. They'd replace the master cylinder but the problem was still there or would come back. They ended up solving the issue by replacing the hydraulic abs unit. I don't know if it's rebuildable or not but I may pick up a used one at some point.
 
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