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2013 MP7 Over fueling problem


steeler
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Hopefully somebody can lead me in the right direction here. I'm working on a 2013 Mph that is black smoking and throwing codes for cylinder #4 cylinder balance, and cylinder #4 misfire.

I replaced #4 injector, that didn't help at all. I've ran compression test which all cylinders checked perfect. When I do the cylinder balance test with tech tool, #4 is way overfueling. 

Cylinders 1 and 5 are near zero in the balance test, 2 and 6 are about -17, and #4 is climbing pretty fast at +56. #3 is -25.

Not sure where to go other than throwing 5 more injectors at it, but that would be a pricey strikeout!

 

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I remember having lots of issues with a certain emission year group of MP7’s. I believe it was around the 14-15 year models. Engines would have lots of injector codes and not running smoothly. The wiring harness was rubbing the top front of the air compressor. Mack sent out a bulletin it at the time. It’s worth a shot,  I remember using a long pry bar to lift up the harness and a mirror to look under it for bare wires , it was hard to reach .

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29 minutes ago, Mackpro said:

I remember having lots of issues with a certain emission year group of MP7’s. I believe it was around the 14-15 year models. Engines would have lots of injector codes and not running smoothly. The wiring harness was rubbing the top front of the air compressor. Mack sent out a bulletin it at the time. It’s worth a shot,  I remember using a long pry bar to lift up the harness and a mirror to look under it for bare wires , it was hard to reach .

Yup, I've changed many harnesses for that problem. Never had one at like this, but I'll definitely be checking that.

Another thing I thought was strange was that the suspect cylinder had a different part number injector, but it crossed to the same part, except it showed as a new injector and not a reman. None of them looked like they had been replaced recently though.

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Problem found! Long story short is original complaint was low power and black smoke. After replacing the injector I found 4 intake manifold bolts broken and cracked manifold. That didn't help the smoking.

Went ahead and pulled dpf and found it completely melted out. O don't have any idea how this thing regened normally and didn't have a single dpf code in it. But oh well!

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