Sometimes when braking it feels like it is jumping

OLIVERERIC423

MEMBER
2013 DODGE CARAVAN
6 CYL
2WD
AUTOMATIC
150,000 MILES

I recently purchased the van listed above. Not long after getting it, about a quarter of the time we would brake, it would feel as though the car was jumping when we got to a complete stop, like it was trying to go but couldn't because it was braked, but when we pressed all the way on the brakes it would stop. It went on for a few days and now when it happens and we press further on the brakes, the car acts as though it shuts off and we have to restart it to get it to go again. We got a check engine light today but all that popped up for it was a code for the Emission System Integrity Motor. It has been changed but the jumping still occurs. I know nothing about vehicles, so any help is greatly appreciated.

Sunday, July 3rd, 2022 AT 2:33 PM

3 Replies

JACOBANDNICKOLAS

MECHANIC
110,126 POSTS

Hi,

By chance, could the jumping be caused by the engine nearly stalling? Is the ABS or brake light on?

I ask because I'm questioning if there is a vacuum leak at the power brake booster. Have you ever noticed a whooshing sound when applying the brakes?

Do me a favor and try this. Turn the engine off. Pump the brake pedal until it gets hard to push. When that happens, hold pressure on it and start the vehicle. Does the pedal smoothly drop lower?

Also, the vacuum brake booster is located under the hood. If you open the hood, the booster will be on the driver's side of the firewall behind the brake master cylinder.

I attached a pic of the booster below. I highlighted the booster and circled where the engine vacuum hose would attach. The arrow in the pic indicates the front of the vehicle.

Let me know what you find.

Take care and Happy 4th of July.

Joe

Image (Click to make bigger)

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Sunday, July 3rd, 2022 AT 10:28 PM

OLIVERERIC423

MEMBER
20 POSTS

I don't think it's the engine about to stall but I've never had one stall on me so I can't say for sure. As for the lights, I do not have any brake or ABS light. I have never noticed a whooshing sound, but I do normally have my music playing so it could be and me not notice it. I followed your instructions, and the brake pedal went down smoothly after starting the car. I did however notice the car seems like it hesitates very slightly to accelerate after I stop, and it jumps whenever it doesn't cut the car off completely. I'm just hoping it's not a transmission issue and if it is, I get it figured out while my vehicle is still under warranty. Thanks for your help! And happy 4th to you as well!

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Monday, July 4th, 2022 AT 2:41 AM

JACOBANDNICKOLAS

MECHANIC
110,126 POSTS

Hi,

Okay, the power brake booster is supplying assistance, so that is good news. By chance, have you checked for engine vacuum leaks? If not, that can cause an idle issue as well. Take a look through this link and let me know if you are comfortable performing the tests:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

If you don't feel comfortable or if you find no leaks, what I'm going to suggest is to have the can-bus scanned for codes.

CAN stands for controller area network. Basically, all the different computers/modules are tied together via a few wires so they can communicate with each other. If there is a code stored, this will retrieve it regardless of the module storing it. Here is a link that shows how it's done. It really isn't difficult, but it does require a scan tool that can perform the procedure.

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Let me know your thoughts.

Take care,

Joe

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Monday, July 4th, 2022 AT 9:06 PM