2015 F150 3.5 Ecoboost misfire

Robert Owner/Technician Mississauga, Ontario Posted   Latest  
Unsolved
Driveability
2015 Ford F-150 XLT 3.5L (G) 6-spd (6R80)
Misfire

Hello there,

INFO ON ATTACHED FILE - attached file was taken after a KAM reset, so the fuel trims would have a change to adapt; - I started the engine up after the KAM reset - engine run time in the attached file is about 3.5 minutes

BACKGROUND INFO - Working on 2015 Ford F150 with a 3.5L Ecoboost. - Customer purchased this vehicle used with about 85,000 miles (US vehicle - so miles on the odometer) on the odometer. - The vehicle has no trouble codes - you can feel a misfire at idle only. Come off throttle, the misfire goes away. Further, the misfire is only felt when sitting in the driver's seat - you can not feel this misfire when placing your hand on the radiator support and/or engine. Also, the misfire comes and goes - you might feel it for 15 minutes while the truck is running in the bay and then the misfire will go away for 10 minutes and come back - Did the basic diag stuff - VE test and engine breaths well on throttle and vehicle accelerates great. Based on the attached file, you can see Bank 2 (i.e. cylinders 4, 5, 6) is running rich so I checked for proper voltage delivery to Bank 2 ignition coils when the circuit was load for all ignition coil - battery voltage at coils = all is well. Fuel pressure does seem to be an issue based upon the information from the rear O2 sensors as per the attached file. - used the Ford IDS to check for misfires - no misfires - used the Ford IDS to do a power balance test - the loss of contribution from all cylinder was about 15% (from what I remember) - used the Ford IDS to shut down injectors - again, loss of contribution was at an even number for all 6 cylinders - customer brought the vehicle to a Ford dealership and the dealership said there was a torque converter clutch lockup issue in gears 5 & 6 when driving. This was the misfire issue according to Ford - customer had torque converter replaced as per Ford's recommendation and customer says there is no more misfiring

SOME OBSERVATIONS - I am clueless how a malfunctioning torque converter would cause a misfire/bank 2 to run richer then Bank 1 - "replacing the torque converter" story from the Ford dealership I thought was "smoke & mirrors" for fixing something on the crank sensor as this crank sensor is mounted behind the left turbo charger and picks up the signal from the ring gear

MILLION DOLLAR QUESTION - how the heck does a malfunctioning crank sensor (if that was indeed the problem) affect one bank to run rich while the other bank runs normal - wouldn't both banks run rich as the crank sensor input affects every cylinder for timing of the injector and ignition?

Thoughts appreciated - thanks in advance.

+1
Interesting
Saifullah Diagnostician
Ottawa, Ontario
Saifullah Default
 

I call this "a failure within parameter". The PCM did not recognize a misfire because the defect of the torque converter clutch was not great enough to flag a misfire code. But it was great enough that the driver could feel the misfire.

0
Default Ð Bounty Awarded
Anthony Technical Support Specialist
Kirkwood, Pennsylvania
Anthony Default
 

Hi Robert: A 10-15 RPM drop in a cylinder is enough to feel it in your ass. I agree with your thought process on the CKP as far as affecting both banks. I'm not sure if it would be rich or lean though. I have 2 questions. 1: Is there any chance that the catalytic converter was replaced and not the torque converter? 2: Any reason that you're using a histograph for that data instead of a line…

0
Default Ð Bounty Awarded
John Owner/Technician
Prospect Park, Pennsylvania
John Default
 

Ford has misfire counter diagnostic are you able to look on IDS or another scan tool to see misfire counts . This to either eliminate non missing cylinders or pinpoint missing cylinder. It has to be less than 1 miss per every 250 revolutions or it would kick a CEL. This would lead me to believe an inconsistency such as cracked coil boot more electrical and less fuel or vacuum.

0
Default Ð Bounty Awarded
Michael Diagnostician
Irving, Texas
Michael Default
   

It's called Power Balance in IDS, Sorry meant Misfire Test.

0
Default Ð Bounty Awarded
Geoff Diagnostician
Lahaina, Hawaii
Geoff Default
 

What makes you think the fuel trim is any different now than it was before he had it fixed? With the LT at 0% and the ST both within ±10% I don't think those numbers were ever indictitive of the issue at all. It may have exactly the same numbers now. Just my opinion, but I see no reason to distrust the dealer on this one. If they know about a TC issue and it fixed the "in your butt"…

+1
Default Ð Bounty Awarded
Agree
Albin Diagnostician
Leavenworth, Washington
Albin Default
 

What did your power balance histography look like before the repairs were made? Does this engine use a dual mass flywheel? If so, I have seen some rather harsh misfires felt by a failing dual mass flywheel, mostly in diesels. In looking over your fuel trims, I don't see anything waving a red flag here.

0
Default Ð Bounty Awarded
Michael Diagnostician
Irving, Texas
Michael Default
 

Repairs require relearning Misfire Monitor Neutral Profile Correction to prevent misfire (was something repaired before the vehicle was sold). If they replaced the torque convertor, they would have performed the relearn. I wonder if they had performed the relearn first, if that would have had resolved the problem. Do you know what the fuel trims are like now?

0
Default Ð Bounty Awarded
Michael Mobile Technician
Clinton, Utah
Michael Default
 

I purchased my 2015 F-150 Ecoboost new in 2015. It has always had what felt like a misfire at idle. In talking to others I am told it is a problem inherent to this model. I now have 214K miles, it still does it at an idle. I guess I just got used to it. I did have at about 100K a real misfire at startup and idle. It had deposits on the intake valves. After walnut blasting and adding a catch can…

+2
Default Ð Bounty Awarded
Albin Diagnostician
Leavenworth, Washington
Albin Default
 

In the last month, I have had 2 of these 3.5 ecoboost F150's in with a misfire under load. They both had close to 100 K miles, and both had a carbon tracked spark plugs. Both had original spark plugs.

+3
Default Ð Bounty Awarded
Helpful
Tanner Instructor
Wellford, South Carolina
Tanner Default
 

The fuel trims that you saw were actually probably “normal” so far every f150 eco boost I have encountered had fuel trims that I would consider to be off. They seem to have fuel control issues from the factory. If you search through Some of the fb groups there is also a lot of talk about drilling a very small hole in the bottom of the inter coolers to allow water and oil to drain out. Apparently…

0
Default Ð Bounty Awarded