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Discussion Starter #1
I briefly mentioned this in a seperate thread (http://www.smartcarofamerica.com/forums/f25/coolant-loss-dilemma-44388/index25.html#post521150) after I had completed an engine swap. Tonight however, I was changing the oil in my other smart car and checked the same wire harness for damage. Guess what I found??? You got it! Wire harness damage where the upstream O2 sensor wire harness and the air injection pump hose cross each other. They've been rubbing together causing wear into the wiring harness. I sealed off the exposed wire and reinforced that part of the harness with plastic wire loom.
Air Injection Pump Hose


Pull the Air Injection Pump Hose back and inspect the wire harness below it.


Both my cars have 50K miles and both had this damage.
 

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Can you post a pic from farther away so we can better see where this wire/hose crossing is located in the engne bay? Is this to the right of the oil filler cap?
 

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Discussion Starter #5
Can you post a pic from farther away so we can better see where this wire/hose crossing is located in the engne bay? Is this to the right of the oil filler cap?
It is to the right of the oil fill cap. The air injection hose is a very distinct looking curved hose (origninal top picture). If you pull the hose back toward you, the wire harness is directly underneath the hose.
 

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Discussion Starter #6
I just checked my friends 08 with 63K miles. His was wearing in the same place although the damage wasn't as bad as mine. He didn't have exposed copper showing yet but it would eventually if left untreated.
 

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so I assume that if that wire actually shorted against something or wore completely through you'd get a CEL and subsequent code re: faulty O2 sensor. But if the problem only went so far as to change the resistance in that circuit slightly, would that effect fuel mixture and if so would it result in a lean or rich condition?

just thinking
 

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Discussion Starter #10 (Edited)
so I assume that if that wire actually shorted against something or wore completely through you'd get a CEL and subsequent code re: faulty O2 sensor. But if the problem only went so far as to change the resistance in that circuit slightly, would that effect fuel mixture and if so would it result in a lean or rich condition?

just thinking
It depends on which wire inside the bundle is damaged. There appears to be six wires within the bundle so it's hard to say exactly what symptoms one would experience.
 

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Bad enough we may have coolant hoses rubbing the frame now we have rubber hoses chaffing wire looms... What's next?? :rolleyes:
 

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ditto - good find- just checked mine, the plastic harness covering was worn through enough that the insulation of the yellow wire is visible but the wire was intact. this at 20K miles

does anyone know if the smart uses UEGO type sensors?

if so these are pretty high tech, self heating and quick responding units that not only help regulate mixture but also current to the fuel pump

doubtful that bare wiring would enhance the efficiency of such a component
 

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Good one Chief...

Ya don't suppose the fact this little motor can rock so much has anything to do with all these rubbing issues, do ya?? :rolleyes:
 

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Ya don't suppose the fact this little motor can rock so much has anything to do with all these rubbing issues, do ya??
I suspect the primary contributing factor is the extremely confined engine compartment and the need for highly compact packaging of the ancillary components, wiring, and hoses.
 

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I suspect the primary contributing factor is the extremely confined engine compartment and the need for highly compact packaging of the ancillary components, wiring, and hoses.

That and a lack in engineering and quality control that has been pointed out...:rolleyes:

With todays computer modeling all aspects of routing and movement can be traced...
 
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