Rough idling slow pick up

Tiny
SIALE
  • MEMBER
  • 2002 MERCEDES BENZ CLK430
  • 4.3L
  • 200,000 MILES
When I start the car runs rough when I'm driving the vibration goes through the car when I put my foot down and slowly picks up. I checked all vacuum hoses I read the codes it says 1, 3, 5, and 6 misfiring. Change 8 spark plugs and it still says number one is misfiring but I changed it. I put a new intake manifold on it MAF sensor and injectors. Appreciate if you can tell me what's wrong. Thank you
Sunday, August 4th, 2019 AT 5:18 AM

7 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Hello,

Did the problem begin after the repair work or did you do the intake to try and fix the problem? Next, can you please give me the code numbers. here is a guide to help:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Next I would do a compression test to see if we have a engine at is mechanically sound. here is a guide:

https://www.2carpros.com/articles/how-to-test-engine-compression

Please run down this guide and report back.
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Monday, August 5th, 2019 AT 1:47 PM
Tiny
SIALE
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When injector wasn't working I tested them all. Would that caused the problem? I'm going to change the other a spark plugs tomorrow. So I let you know what happened. But would that one injector cause multiple misfires?
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Wednesday, August 7th, 2019 AT 1:41 AM
Tiny
KEN L
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It can because the mixture is trying to correct itself. When you remove the plugs keep them in order and check the color this will help us see which cylinder is misbehaving.
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Wednesday, August 7th, 2019 AT 5:38 PM
Tiny
SIALE
  • MEMBER
  • 13 POSTS
Yeah, I got 3 5 and 6 misfiring only I've changed all the spark plugs now and there's 3 5 and 6 misfiring. It's running a lot better though. What would be be causing this 134 5 6 7 and 8 misfiring? Now it's only 3 5 and 6. What else could cause this? How do I check the coil pack and how do I check the mass air flow sensor? If it's faulty if I unplug it when the car is running and it shuts off is it working or if it keeps running is it working?
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Sunday, August 11th, 2019 AT 6:19 PM
Tiny
KEN L
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Checking the coil pack is not too bad this guide will help you:

https://www.2carpros.com/articles/how-to-test-an-ignition-system

As far as the MAF sensor that is more difficult to test because you would need a new sensor to check the difference in values. The MAF is a normal wear item and should be replaced after 100,k here is a video that shows the job being done on a similar car with diagrams below to show you on your car.

https://youtu.be/QOMiXhx2hbI

Check out the diagrams (below). Please let us know what happens.
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Monday, August 12th, 2019 AT 11:20 AM
Tiny
SIALE
  • MEMBER
  • 13 POSTS
I replaced it with the new Mass air flow sensor and is running a lot better but 3 5 and 6 is still is misfiring and there's still got like a vibration going through the car. When I put in first gear you can feel the rough idling. Still I don't know what it would be. Anything would be appreciated that I can check.
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Tuesday, August 13th, 2019 AT 5:37 PM
Tiny
KEN L
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Can you please shoot a quick video with your phone so we can see what's going on? That would be great. You can upload it here with your response. I need to see the engine running. Also, I need to see the engine cranking over that way I can tell how the compression is.
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Wednesday, August 14th, 2019 AT 11:03 AM

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