Car bucking and check engine light came on

Tiny
JIMMY341
  • MEMBER
  • 2006 JEEP COMMANDER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 110,000 MILES
Okay, so my car started bucking at around 2 on the rpm while driving and the check engine light came on. I had it hooked up to the computer and it is saying a misfire on number six. So I did it all; replaced the plugs coils and in injector on number six and it is still doing at at the 2 rpm while driving. When this happens I can pull over and shut the car off and restart then drive without an issue. Sometimes it does and sometimes it does not. Seems like more in the mornings. I was told to try either the camshaft or crankshaft sensor. Any ideas on which one or maybe something else?
Friday, November 23rd, 2018 AT 8:59 AM

7 Replies

Tiny
STEVE W.
  • MECHANIC
  • 15,546 POSTS
Does temperature seem to effect it? Sounds like it may if it does it more in the AM after the engine get's cold. Can the tool you are using view live data, or is it just a code reader?
If it can see live data you could watch the data to see if either sensor is dropping out when you hit the 2,000 rpm mark. Being this is a 3.7 engine it could also be a bad valve seat or valve as well. They are known for having issues. For that a leak down test may show you some good information.
Another possibility would be a bad wire going to the coil. For that you would need to test the circuit with the engine running and see if it started to drop out when you hit 2,000. About the only reliable way to do that is with an oscilloscope however.
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Friday, November 23rd, 2018 AT 1:27 PM
Tiny
JIMMY341
  • MEMBER
  • 4 POSTS
Temperature does not seem to affect it. Had it checked again on the computer and the o2 sensor bank 2 shows up first running lean and again misfire on number six but after it was cleared this time it also showed a code for something like throttle body they told me. The idle is slightly rough but you really feel it now between 1.5 and 2 on the rpm after that it seems okay. Any chance it could be just the sensor? Some say yes and some say no. The garage is kind of giving me the run around.
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Thursday, November 29th, 2018 AT 5:29 PM
Tiny
STEVE W.
  • MECHANIC
  • 15,546 POSTS
Throttle body will not cause a single cylinder misfire. Sounds like you need to find a better shop, that is not easy these days. Have them run a compression test. That should show if it is a bottom end or valve issue.
Rough idle is a misfire, Jeep takes a bit to set a code if it vanishes off idle. The way to see that is with a misfire counter PID on a scan tool, you can watch it and count the times it registers a misfire. However to repair it takes some testing. The 3.7 can be a picky engine to work on if you do not see them often.
What general area are you in? Perhaps one of the folks here could point you to a better shop or a mobile diagnostics outfit.
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Thursday, November 29th, 2018 AT 6:38 PM
Tiny
JIMMY341
  • MEMBER
  • 4 POSTS
Thank you! I am in the 18643 zip code. Just outside of Wilkes Barre Pennsylvania.
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Thursday, November 29th, 2018 AT 6:40 PM
Tiny
STEVE W.
  • MECHANIC
  • 15,546 POSTS
I know of a couple but both are two hours away from you. Quite a drive with a bum Jeep.
One thing you said about shutting it off and sometimes it restarts and runs fine? That could be a short in a wire on the engine that moves just enough that it clears the problem. You could try running the engine and prodding the wiring harness to see if you can make it run okay, then look close at the area that made it run better.
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Friday, November 30th, 2018 AT 10:05 PM
Tiny
JIMMY341
  • MEMBER
  • 4 POSTS
So I took the jeep to a well know garage today. They did every test under the sun and traced every wire. Turns out it is the part of the ecm that controls the #6 injector. So here is where in need your opinion. A new ecm installed is 750 bucks but one of the guys at the garage told me on the side that the most common problem being that the solder breaks where the connector plugs in. Being the only problem is that one injector tells him that its that one connector and not the whole ecm.I checked out many videos on YouTube and this serms to be a common problem. Do you think its worth a shot to open it up carefully and check out the solder connection? Thank yoy
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Monday, December 3rd, 2018 AT 6:05 PM
Tiny
STEVE W.
  • MECHANIC
  • 15,546 POSTS
Well, you do not really have anything to lose. You might be able to repair it and save a bunch of money. Bad solder joints are one of the results of the use of lead free solder. This is one of the things I was thinking about with the temperature question.
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Monday, December 3rd, 2018 AT 7:05 PM

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