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Misfiring, scan says MAP Sensor and Ignition Coil

Tiny
JC-842
  • MEMBER
  • 2007 DODGE CALIBER
  • 2.0L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 144,000 MILES
Repaired car after two weeks of trouble shooting Intake manifold and throttle body replaced, also intake runner control valve replacement. Car ran fine all lights out. Lightning bolt display is off engine light was off drove car ran fine. Upon putting the engine cowling back in place I had to move the wiring harness and immediately car started misfiring. Scan says MAP sensor and ignition coil. I also replaced the PCM/ECM.
So. Over $500.00 later turns out I still have a open wire some where.
Where do I start. Need help. Thanks JC.
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Tuesday, August 24th, 2021 AT 4:44 PM

9 Replies

Tiny
STEVE W.
  • MECHANIC
  • 13,003 POSTS
What are the codes the car currently has? I would remove the cover and look at any areas on the harness that are close to the engine block or heads, or the exhaust. All of those areas could be an issue. The codes should point at systems where you will be able to test the wiring to find a broken wire or shorted. A simple test light and test meter would be the test gear.
https://www.2carpros.com/articles/how-to-check-wiring
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Tuesday, August 24th, 2021 AT 7:08 PM
Tiny
JC-842
  • MEMBER
  • 181 POSTS
Test 3/4, no voltage or ohms per test instructions.
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Wednesday, August 25th, 2021 AT 7:10 AM
Tiny
STEVE W.
  • MECHANIC
  • 13,003 POSTS
What were you testing wire wise? There are multiple circuits involved in these items, that is why I asked for the codes, to pull up the relevant wiring diagrams for you and have you test the wires. The MAP can have multiple codes as can coils.
They don't appear to share any components other than the PCM and the engine grounding.
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Wednesday, August 25th, 2021 AT 9:36 AM
Tiny
JC-842
  • MEMBER
  • 181 POSTS
I'm sorry I wasn't thinking, Joe has sent me diagrams to trouble shoot some wiring issues concerning coils and my MAP sensor. I was referring to the voltage test on the MAP harness connector at pin 3 I believe. And then the ohms concerning that same connector. This is an ongoing problem
There's a short somewhere.
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Wednesday, August 25th, 2021 AT 9:43 AM
Tiny
STEVE W.
  • MECHANIC
  • 13,003 POSTS
MAP should have 5 volt bias, ground and signal out. Ground is through the PCM but you can tie it to chassis ground if it has an issue during testing as it is a simple pass through in the PCM.. The 5 volts on the brown wire with light green trace on pin 3 of the MAP is shared between the cam position, the MAP and the flow valve in the intake manifold. You said it had a misfire and running poor, if that 5 volts was shorted it could cause that. I would go to the MAP and check for voltage, then unplug the cam sensor and the manifold control. If one of those is shorted it can pull the 5 volts down.
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Wednesday, August 25th, 2021 AT 2:52 PM
Tiny
JC-842
  • MEMBER
  • 181 POSTS
Good info. I've found pulling on the harness where the fuel injectors and harness run across the valve cover seems to make the engine just really run really bad. I'm thinking about replacing the entire loom/wiring harness. From another Dodge Caliber.
Trouble shooting electrical problems
Is really expensive unfortunately I don't have the experience needed to do this myself. I spent the day with magnifier and looking for breaks in the wiring. Until I was cross-eyed. I've come to realize automotive electrical work is above my level. Hopefully I can replace the whole harness and solve the problem for $30.00 instead of hundreds. Thank you. JC
.
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Wednesday, August 25th, 2021 AT 7:47 PM
Tiny
STEVE W.
  • MECHANIC
  • 13,003 POSTS
Okay, if you found that pulling the harness caused issues, make the areas you move smaller. Take the harness between two hands about 3inches apart and tug on it, any change? Yes look at the wires in that area for hourglass marks in the insulation, it's possible for a pinhole to let in moisture and air over time and corrode the wire apart inside the insulation. No change, move farther down the harness. When you find the area you can remove any wire loom or tape around the harness and test each wire by giving it a good tug, a good wire will be fine, one that is corrode will pull apart and break, then you have the area to repair.
I would also check any connectors or connections that move when you move the harness. Chryslers are bad for poor grounds and corrosion in connectors. Reason I say this is that you know that most of your harness is okay, installing a used one could repair the issue but if it was one of the connections to the harness the problem would still be there.
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+1
Wednesday, August 25th, 2021 AT 7:59 PM
Tiny
JC-842
  • MEMBER
  • 181 POSTS
I'll try tomorrow and let you know what happens. Seems to be okay right now no check engine light on at least.
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Wednesday, August 25th, 2021 AT 8:05 PM
Tiny
STEVE W.
  • MECHANIC
  • 13,003 POSTS
No rush, We'll be here. Tracing a wiring fault can take some time.
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Wednesday, August 25th, 2021 AT 10:50 PM

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