Misfire That I cannot seem to Fix. I TRIED! Also lunging RPMs.

[plymouth383]

so here is the situation. I own a 2011 Ford Flex Ecoboost. It has 130k miles on it. It has been great up to this point. I have had hardly any problems with it. I am a mechanic by trade and do all my own work on vehicles. this one has me puzzled though.

It is tuned from Torrie at Unleashed.
It has a 3 bar Map Sensor
180 degree thermostat

About 6 months ago it began to misfire. I have experienced the misfires before and usually it indicates plug time on these. also a few days later it started this fun little lunging thing where the rpms rise up and down while going down the road.

1. I ordered up a set of the sp534s and installed them at .030. thought all was well until a couple days later it started to misfire again. figured maybe it was a bad plug I got. so bought another set reinstalled still no help. 

2. figuring the mileage was high i did some research and came to the conclusion that possibly my intake valves are all coked up and needed to be cleaned. I pulled the intake apart and shot some walnut shells at the valves. The only ones that were truly really bad were the front two cylinders where the air tends to not hit directly. Got them all nice and clean.

3. I installed a brand new set of OEM injectors. I replaced all six. Figured while i have everything apart. old injectors looked good nothing to indicate a problem.

After reassembling everything I took it out for a test drive. Still misfiring. also still lunging. Now I was getting confused.

I have done a couple of datalogs after this to try and confirm if anything else was reading off and causing the misfire. Everything reads normal. The car misfires under high load lower rpm sessions. Say accelerating from a yield sign at about 15mph up to 40 with about 25 percent throttle. It will just continuously misfire until you tip into it and get it to downshift and accelerate. The only thing that is evidenced in the logs is the RPM change from the misfire. It runs very strong otherwise with plenty of power. it only does this is this range nowhere else. Also around the 25-45mph if you hold the throttle steady the RPMs will fluctuate up and down about 150-200 RPM. It does this constantly. The Throttle angle actual reflects this on the log as well. You can see it rise up and down with no change from the pedal, only the change from the PCM commanded throttle. It will move as much as 2 degrees on perfectly flat unchanged road. Even with the cruise control on it will not stop the lunging. I do not see anything else moving with this except for boost going up and down maybe. I am using the SCT software to datalog and I have to say the program is a little buggy. but the data doesnt seem compromised just hard to view.

So after doing some more reading and research I figured out that the TIP has a big play in the way that everything works. I know these are Speed Density so there is no MAF or anything like that to skew readings.

4. I loaded up the Stock Tune and then reinstalled the 2 bar map sensor. Went for a test drive and everything seemed ok. then a day later it came back. same things. Misfire and lunging.

5. I took the 3 bar map sensor I had for the tune and placed it in the TIP position. Same part number and everything. No change still misfiring and lunging.

really confused now I am just grabbing at strings.

6. I installed a brand new throttle body with new TPS and Motor. No change still lunging and misfiring

7. I installed 2 fresh wideband OEM Bosch O2 sensors. Runs smoother up top now but still no stopping of the misfire or lunging.

8. I verified and double checked the knock sensor wires even though there is no evidence in the log of them being an issue and the loom is in great shape. no chafing at all.

9. I installed 6 new OEM coils and 6 new spark plugs gapped at .30 then .28. Still misfiring and lunging.

I am just really frustrated at this point as usually I am not this clumsy or lost on a problem like this. I have tried to figure out how the system works and cannot think of anything else causing this issue. There has been NOT ONE check engine light or code set. The PCM thinks everything is peachy. Usually I diagnose and work it out step by step to reasonably determine the underlying cause but I finally am at a loss on this one.

The only variable that has been truly determined is that if you disconnect the battery or do a KAM reset that the problems soften and the progressively get worse. The misfire happens at any time. The fluctuating lunging rpm thing happens worse when it is cold and then gets better as it warms up. like 300 rpm in the morning but then when near work maybe 150rpm. you can almost always get it to misfire in the same speed rpm load range as stated above. Short of replacing the PCM i think I have covered everything that could be related to these instances.

This morning on a whim I disconnected the TIP sensor. It stopped doing the lunging but I could not determine the misfire bit really because of the Limp Mode and wrench light. Plugged it all back in and just went to lunch this afternoon and misfired right out of work and was lunging. It is really annoying to drive at times now. if you punch it while it does this is downshifts and takes off like a bat out of hell. it is powerful and doesn't feel mechanically weak.

PLEASE HELP! I am out of ideas for now. I can post some logs if requested tonight when I get home. Thanks for any help.

[F150Eco]

Sounds like a doosey. I want to tag along.

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[SHOdded]

Three thoughts I had:  engine, PCM, torque converter.  Engine seems to be an UHOH with the Flex for some reason.  You noticed change after KAM reset, that means the adapations are not working, either because there is something wrong with the engine/control system, or the PCM is at fault.  Torque converter because if it has issues, it will keep locking/unlocking with no change in load/throttle input whatsover.

No codes being set COULD point to a faulty PCM, has happened with prev Gen SHOs, so still a possibility here.

What oil/filter are you using?  What gas?  Any oil leaks in the plug wells or deposits on the plugs?  Valve cover gasket leaks do happen, and can cause misfiring symptoms.

Are you monitoring lambda/afr?  Any fuel smell out the exhaust, any smoke?  Checked the intercooler and turbo piping for pooling oil?  How much boost are you seeing?

Def post logs.  Our membership may be able to figure out what's off ...

[hawkeye93]

Off the top of my head, maybe a throttle position sensor?

[plymouth383]

Three thoughts I had:  engine, PCM, torque converter.  Engine seems to be an UHOH with the Flex for some reason.  You noticed change after KAM reset, that means the adapations are not working, either because there is something wrong with the engine/control system, or the PCM is at fault.  Torque converter because if it has issues, it will keep locking/unlocking with no change in load/throttle input whatsover.

No codes being set COULD point to a faulty PCM, has happened with prev Gen SHOs, so still a possibility here.

What oil/filter are you using?  What gas?  Any oil leaks in the plug wells or deposits on the plugs?  Valve cover gasket leaks do happen, and can cause misfiring symptoms.

Are you monitoring lambda/afr?  Any fuel smell out the exhaust, any smoke?  Checked the intercooler and turbo piping for pooling oil?  How much boost are you seeing?

Def post logs.  Our membership may be able to figure out what's off ...

The engine seems to be in great health. I use a Motorcraft filter with Amsoil signature series oil. It has always had a synthetic it whole life. It hardly uses any oil. I mean in 5000 miles I usually use less than 1/4 to 1/2 a quart. It runs very strong and clean. hell when I pulled the intake the valves had some gunk on them but honestly not enough to block any sort of airflow. No smoke or foul odors except the stupid PTU vent which is common on the heavy flexes. I installed a drain plug in this and routinely flush it out. It gets 93 octane from known good sources. I have a CTS-V that I drive the Flex is my wifes. I take very good care of my vehicles. This has had the coolant flushed and replaced at 80k, and the transmission fluid changed every 50k. I have the fluid on the shelf to try the transmission again and may give this a whirl. I would figure though that if the torque converter was unlocking that the input and output speed sensors would then be throwing a trans code for this issue. I do know that it is similar in feel to the 4r100s and 4r70ws that had some old fluid in it and unlocked and locked the converter really quickly. I would say this would be it for this if it was doing it at say 45-55mph steady cruise with a sudden throttle tip in. I am not sure how the lockup is on the ecoboost though.

every time that I have pulled the plugs the wells are bone dry and very clean. I check every time to verify. I do monitor the Lambda on the logs. I have not seen anything on this that points out of the ordinary at least to me. I am no professional on that but I do understand Lambda and how it relates to fueling. I will try and pay a little closer attention to the values and see if possibly it is leaning out when the misfires occur. The only other fuel item I can think of is the HPFP but it seems to be outputting a good amount of pressure. I will verify the max boost again on the way home.

CAC tubes look good. There is some light oil in there but nothing serious. I don't think it is chugging a bunch but then again maybe the intercooler could stand to be removed and cleaned.

I feel that the problem is prevalent and serious enough that a code should be flashing. Which is funny that the PCM thinks it is within normal operating range. The PCM is commanding the change in throttle position for the lunging. you can see that on the log. I am just not sure why it is commanding that and if that is related to the misfire.

[plymouth383]

Off the top of my head, maybe a throttle position sensor?

Oh how I wish it was that easy. I though that myself because of the commanded throttle position from the PCM. I replaced the entire throttle body to include the throttle position sensors and the motor. Did not change a thing but gave me a shiny part lol.

[SHOdded]

Ok, well, time for datalogs  

[pmezo33]

I'd think torque converter with the jumping rpm's, but you wouldn't be getting misfires like you are.  Which cylinders are misfiring?  Always the same ones?  Any other codes besides the misfire codes?

[plymouth383]

I'd think torque converter with the jumping rpm's, but you wouldn't be getting misfires like you are.  Which cylinders are misfiring?  Always the same ones?  Any other codes besides the misfire codes?

The problem is there are absolutely no codes. None for misfire or anything. I feel the misfire and hesitation as well as lunging

[F150Eco]

I'd think torque converter with the jumping rpm's, but you wouldn't be getting misfires like you are.  Which cylinders are misfiring?  Always the same ones?  Any other codes besides the misfire codes?

The problem is there are absolutely no codes. None for misfire or anything. I feel the misfire and hesitation as well as lunging

That gets frustrating.

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[glock-coma]

Maybe a compression check to confirm everything internal is ok.

[pmezo33]

I'd think torque converter with the jumping rpm's, but you wouldn't be getting misfires like you are.  Which cylinders are misfiring?  Always the same ones?  Any other codes besides the misfire codes?

The problem is there are absolutely no codes. None for misfire or anything. I feel the misfire and hesitation as well as lunging

No codes when it's misfiring?  Are you 100% sure that it's actually misfiring?  Is that even possible? 

No engine codes and surging rpm's, plus the fact that you've done plugs/coils/injectors, makes me think you've got a transmission problem here.

[dubcitySHO]

Does your datalog config monitor misfire? 

I'm on the torque converter band wagon as well, as your symptoms are very similar to my own when I needed a new converter.  Hesitation/jumping RPM/stuttering, but only when under partial lockup.  If I accelerated even at say ~35% throttle, the symptoms would disappear.

[66 Galaxie]

I'm on the torque converter bandwagon too.  Have you tried looking at requested vs actual torque converter slip data when the shudder occurs?

[plymouth383]

I'd think torque converter with the jumping rpm's, but you wouldn't be getting misfires like you are.  Which cylinders are misfiring?  Always the same ones?  Any other codes besides the misfire codes?

The problem is there are absolutely no codes. None for misfire or anything. I feel the misfire and hesitation as well as lunging

No codes when it's misfiring?  Are you 100% sure that it's actually misfiring?  Is that even possible? 

No engine codes and surging rpm's, plus the fact that you've done plugs/coils/injectors, makes me think you've got a transmission problem here.

I may be leaning towards that. It does happen to feel like it does not want to downshift sometimes. but really nothing to extreme feeling other then the lunging and what feels like a misfire.