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Cannot brake in drive and no acceleration

Tiny
ZOMORU
  • MEMBER
  • 2008 KIA SEDONA
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 155,000 MILES
I have the confirmed engine code P0300, P0302, P0304, and P0018. Also P0306 and P0022 for pending code. I was trying to diagnose my brother’s car and I notice after driving a few feet to a stop, I no longer could accelerate thereafter. The brake was also not working(became very stiff) I had to put it to neutral(allow me to brake and rev up the engine) I put the car back in gear and there’s no rev, it’s slowly creeping forward since I couldn’t brake. I have only checked two spark plug and it was dry and black (running rich?).
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Friday, October 11th, 2019 AT 8:13 PM

11 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
Welcome to 2CarPros.

Black on the plugs does usually indicate a rich fuel mixture. However, based on your description of the stiff brake pedal, I suspect there is a major vacuum leak to the brake booster causing all the problems.

Do me a favor. Check the vacuum supply to the brake booster for damage and make sure it is connected. If everything appears good, remove the vacuum supply hose and plug it. Then confirm there are no vacuum leaks on that hose.

When it's plugged, does the engine run any differently? Please keep in mind, you will have no brake assist with the hose removed, so the pedal will be hard to push. (just in case you drive it)

I attached a picture of the booster and the hose I'm referring to. Check that and let me know what you find. Also, if everything checks good, then check to see if there are any other major vacuum leaks. Make sure the PCV is connected, the vacuum supply has no leaks, and make sure the valve is not stuck open.

Here is a link to help find a vacuum leak:

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

As far as the codes you indicated, two are related to timing. One is the oil control valve to the VVT and the other the camshaft position sensor. This too can be causing the misfiring codes, but shouldn't be causing brake issues.

Let me know what you find.

Take care,
Joe
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Friday, October 11th, 2019 AT 8:34 PM
Tiny
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  • MEMBER
  • 12 POSTS
I haven’t checked the brake yet, but I found a huge cut in the air intake hose. I’ll replace that and see what’s up.
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Saturday, October 12th, 2019 AT 4:14 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
Welcome back:

That certainly can cause issues. Let me know the results.

Take care,
Joe
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Saturday, October 12th, 2019 AT 7:14 PM
Tiny
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  • MEMBER
  • 12 POSTS
Well, the brake problem is fix and I can now drive it, but it’s still misfiring in multiple cylinders. I’m not sure but I think I also hear engine knocking a few time.
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Thursday, October 17th, 2019 AT 5:25 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
Welcome back:

One job fixed. Now, can you provide me with the diagnostic trouble codes that are present? If you clear the codes, which ones return?

Also, since there was one major vacuum leak, chances are there are more. Do me a favor, if you have a live data scanner, go to fuel trims and upload a picture of the STFT for me to see. That will help me determine if there are additional vacuum leaks or even a fuel pressure related issue.

I will watch for your reply.
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Thursday, October 17th, 2019 AT 7:17 PM
Tiny
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  • MEMBER
  • 12 POSTS
After I clearer the code and went for a little drive, P0300 came back as confirmed and P0300, P0302, and P0304 came back as pending.
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Thursday, October 17th, 2019 AT 8:25 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
Welcome back:

The P0300 still leads me to believe there is a vacuum leak. I can't read the image you included. Is that of the fuel trims? Also, have did you check for other vacuum leaks?

Let me know.

Joe
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Thursday, October 17th, 2019 AT 9:29 PM
Tiny
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  • MEMBER
  • 12 POSTS
The STFT for bank 1 average out to 20, bank 2 average out to about -25. I honestly didn't check for vacuum leak. I replaced just the air intake. Checked the filter and it's okay. I also have a carburetor and MAF sensor cleaner. What should I be checking?
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Friday, October 18th, 2019 AT 9:12 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
Interestingly, the fuel trims are way off. A +20 indicates a lean fuel mixture with the computer trying to add fuel to compensate and the -25 indicates the opposite. Since both banks are that far off, I suspect somehow air is getting into the system before the converter. Are there any exhaust leaks? Also, follow the link attached above for testing for a leak. One last thing. Has anything been done with the oxygen sensors?

Let me know.

Joe
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Friday, October 18th, 2019 AT 7:49 PM
Tiny
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  • MEMBER
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Okay, I found an exhaust leak. I don't think anything was done to the O2 sensor, but yeah. I guess I'll just have to get the car to the shop. Thanks a lot for the help.
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Saturday, October 19th, 2019 AT 5:03 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
Welcome back:

Let me know what they find. If you have a leak, chances are that is allowing air into the system before the converter and 02 sensor and creating a lean mixture. The computer is trying to adjust the fuel mixture to compensate.

Let me know, Your response may help others too.

Joe
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Saturday, October 19th, 2019 AT 6:19 PM

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