2015 Transit 350 Misfire question

Sam Mobile Technician Michigan Posted   Latest   Edited  
2015 Ford Transit-350 3.5L (G 99G) 6-spd (6R80) — 1FTSW2CG5FKA17756
P0300 — Random/Multiple Cylinder Misfire Detected

What I have here is a transit 350 100K miles that has a miss under load cylinder 6. Sometimes cylinder 1 varies other times. I started with a coil amp test hoping for direction. The shop has replaced coils and plugs and several attempts at decarboning the intake valves. This van will be driven to a jobsite and idles all day. I did in cylinder in 3 cylinders and am returning today to get some more tests. I see differences in these tests and am starting to think stretched chains. Cam crank correlation, other 3 in cylinders and intake vacuum tests will be done today at minimum. This is the spare van for a fleet so it sets more than the rest. Just wondering if anybody has any suggestions of other tests that should be performed. More than likely it will get an entire engine due to its idle time. I havent worked on many of these. Usually the F150 I do diagnosis on need chains so bad they are noisy. 

Update: The customer has elected to put a replacement engine in due to idle time. A cam crank correlation with the pico did show some stretching in the timing chain. Not enough to merit replacement in my opinion. One of the struggles as a mobile guy you never know the resolution. This is a company van that they cannot afford to have sitting. 

Walter Owner/Technician
South Carolina
Walter Default

Sam does cyl 3 drop out on power balance under load driving too?? i recently worked on one where the cat was partially restricted And caused the condition I experienced And did not effect the other two cylinders on that bank???? replaced the cat and problem solved. Chased it for a bit also with same similar test you have shared. Hope this helps. Buzz

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Carlos Mobile Technician
Puerto Rico
Carlos Default

According to walter​.​Ihave also passed your concern

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Albin Diagnostician
Albin Default

What are the fuel trims doing? Can you get a FRTD on one trim capture, and another at an extended idle?

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Ray Diagnostician
Ray Default

We need to know the bank to bank FTs under load and at idle. Post a capture of the pressure transducer in the intake and in the exhaust while cranking. The GIFs show the differences of where the EVC/IVO occur between cyl 2 and cyl 6

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Geoff Diagnostician
Geoff Default

IDS captures of the Histograph for VCT Variance should help with any stretch or phaser suspicions.

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