2018 Transit 2.5L Misfires P0300 reason unknown

Robert Diagnostician Florida Posted   Latest   Edited  
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2018 Ford Transit Connect XL 2.5L (7 CNG) 6-spd (6F35) — NM0LS7E70J1349948
P0300 — Random/Multiple Cylinder Misfire Detected
Vehicle Misfires At Cruise Under Light Acceleration

scan P0300 mode $06 shows misfires in all cylinder we did find #4 spark plug an ignition boot carbon tracking. Replaced coil and spark plugs still misfiring on several cylinder in mode $06 cylinder #2 and #3 shows more. When driving the vehicle it feels kinda like the torque converter is turning on and off randomly at 40-40 mph. However when the "Feeling" happens the misfire PID records another misfire each time. We did some in cylinder testing and leak down testing and found there was something appearing to be going on where the exhaust valve opens and the intake valve closes. Still learning this way of diagnosis so a little insight would be helpful. I have included the test for #1 cylinder ( #4 cylinder is the same ) and #2 cylinder in question and #3 cylinder looks just like #2 in the area of concern. We also did cylinder leakage test and cranking test compression test. Cylinder #1 175psi cylinder #2 160 psi cylinder #3 160 psi and cylinder #4 178 psi . Leak down test showed all 4 cylinders with almost no leakage.

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Dave Mobile Technician
Ohio
Dave Default
 

Did you try a crank profile relearn? This can cause weird running concerns on a Ford.

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Robert Diagnostician
Florida
Robert Default
 

yes i did and I have cleared the KAM prior to doing it as well.

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Ray Diagnostician
Ontario
Ray Default
 

Robert, your running compression degree Rulers are set for one 360 degree crankshaft revolution. The Rulers should mark the 4 piston stokes of 2 crankshaft revolutions or 720 degrees between compression stokes. You could try the transducer in the intake and in the exhaust while cranking to check for any valve issues.

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Robert Diagnostician
Florida
Robert Default
 

yes thanks i see I did that on one of them :0) When i get this vehicle back I will check that Ray thanks for your input.

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Stephen Technician
Tennessee
Stephen Default
 

- I see the exhaust, all 4 cyl's, opening at about 20*BBDC. Usually the exhaust opens at about 45* BBDC. The intake is closing at about 60ABDC. That is usual. So, it looks to me that the exhaust is retarded about 20 degrees. The late opening also gives a late closing but with the intake at normal it effectively creates an extra 20 degrees of overlap. I think that that is the feature that you saw…

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Robert Diagnostician
Florida
Robert Default
 

i did not have the exhaust camshaft actuator unplugged when i did this however i wouldn't think it would be commanded at idle. I also dont see a spec for the actual exhaust valve opening which means i would need a known good one to compare. Anyone have a know good waveform for this vehicle by chance?

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Ray Diagnostician
Ontario
Ray Default
 

The scan data should have Desired and Actual VCT pids. Graph them at idle and while cruising, but I think the PCM would set some VCT codes if there was a problem.

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Robert Diagnostician
Florida
Robert Default
 

I will also look at that Ray i have alldata and it does not show cam shaft opening and closing events in mechanical specs would you happen to have that in your system ?

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Ray Diagnostician
Ontario
Ray Default
 

I don't have the specs. Can you force the misfires to occur during a brake torque in reverse near 1500 rpm? If the COPs have only 2 wires, you can scope the control side of the COPs and compare the burn voltages on the non misfiring cylinders with the misfiring cylinders, to check for lean or rich injectors. On this 01 Infinity, I ran one strip of aluminum tape on top of the 3 front COPs. I…

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Robert Diagnostician
Florida
Robert Default
 

i am unable to get it to misfire in the bay brake torque when i get it back i will check primary on all 4 cylinders at cruise where it does it and have a look. it may be a week or so before i get it back. Its a fleet vehicle and they dont feel its bad enough to chase just yet. Thanks so much for your input and suggestions.

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Ray Diagnostician
Ontario
Ray Default
   

Hi Stephen, this known good capture is from am 08 Nissan Rogue 2.5 and the EVO 8.3 deg BBDC The PSD file shows the EVO 6.8 deg BBDC

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Stephen Technician
Tennessee
Stephen Default
 

Thanks Ray, I reviewed John Thorton’s In-cylinder Pressure Transducer course today. None of the references sited in the course allowed for anything under 30 degrees. I have not seen any other reference or case study show that. It seems you have to have a known good or technical data before making any assertions.

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