Got 99 problems and my Gen 1 is 1

[2011reptar]

Have you looked at the IAC?

I looked at the throttle body and cleaned it. Throttle % in Forscan looks stable as well. Figures.

 

[Guardrail]

Have you checked for a cracked exhaust manifold or broken stud? My truck did weird stuff like that when I had a crack between the Number 6 and 7 cylinders.

 

[2011reptar]

Well, compression looks fine…

 

[2011reptar]

Have you checked for a cracked exhaust manifold or broken stud? My truck did weird stuff like that when I had a crack between the Number 6 and 7 cylinders.

I haven’t, but I will. I’m starting to think it’s exhaust related, also because that’s basically all that’s left aside from the ECU. It is hard to believe an exhaust issue would only affect one cylinder… but maybe the misfires I’m seeing are a red herring to the idle problem anyway. Could maybe be a slightly weaker valve spring on that cylinder or something so it’s the one showing misfires, I have no idea. It’s odd it doesn’t produce misfires at a high rate, even when replicating the shudder. 5-10 per minute is still well within normal spec.

I’m out of ideas though. I’m gonna try to get the 02 sensors off and replace them as well as bore scope the catalytic converters.

 

[MTF]

Just a little FYI, early 2011 had cam shaft issues and would start galling between lobes and rockers.

But like most suggest. unmetered air and/or exhaust leak, dirty MAF sensor and weak O2 sensors, weak battery, bad fuel and/or water in the tank, low octane, etc... will produce misfires.

A proper smoke test will expose any leaks once and for all.
I had it done when chasing down a too lean/rich condition, once the tech wiggled the Canister purge valve, smoke was detected.
The valve itself was good, but the O rings were not.

 

[pat247]

I haven’t, but I will. I’m starting to think it’s exhaust related, also because that’s basically all that’s left aside from the ECU. It is hard to believe an exhaust issue would only affect one cylinder… but maybe the misfires I’m seeing are a red herring to the idle problem anyway. Could maybe be a slightly weaker valve spring on that cylinder or something so it’s the one showing misfires, I have no idea. It’s odd it doesn’t produce misfires at a high rate, even when replicating the shudder. 5-10 per minute is still well within normal spec.

I’m out of ideas though. I’m gonna try to get the 02 sensors off and replace them as well as bore scope the catalytic converters.

It sounds like you have replaced most/all components that could cause this problem. That said, I would do the complete idle relearn process to see if it corrects the problem. The relearn process takes 15-30 minutes and should not be rushed. This is how I do this procedure, turn off all accessories such as headlights, HAVAC and radio. Then disconnect the negative battery cable for at least 1 hour but over night is better. Reconnect the negative battery cable and start the truck without touching the throttle, let idle for 5-10 minutes then foot on brake put in gear(R) and hold for a minute then release brake and move a few feet brake shift to N wait a few seconds and shift to D release brake and move a few feet and brake again and shift into P. Repeat a few times then turn on accessories and make sure the AC is on max and repeat a few more times. Go for a short test drive and you're done.

If still having issues I would recomend a fuel system cleaner such as BG 44K. Good luck

 

[Canuck714]

I have never liked the low rpm idle from the factory. When running bigger tires like 37's it puts way too much strain on the power steering pump to be at 500 rpm.
I always bump mine to 750 rpm. Try that and see if the issue goes away.

 

[2011reptar]

Thanks for all the info and suggestions to everyone who replied.

Today I replaced the upstream 02 sensors, and the remaining 4 injectors as well as soaked the cylinders with sea foam. It smoked up a lot of carbon, but still runs the same.

Following the compression test, I did use a bore scope and the cylinders look good, still has a lot of cross hatching. I actually got lucky and had shut the engine off right when a valve was open so I got to see it as well and it’s the same as the piston head, a little dirty but no pitting or damage.

At this point, the only thing left could be a weak valve spring that isn’t broken yet, a slightly bent valve, or the ecu itself. When I had the valve cover off, everything including the cam looked basically new. I’m pretty tried and broke from the parts cannon the last week or so, so I’m just gonna roll with it for now as much as I hate to.

If it truly is just carbon, the seafoam in the oil should take care of that in another 100 miles or so.

I’ll keep the thread updated if anything changes. I’ll also look into a tune to raise the rpm, could just be the can profile after 110k miles, I have no idea. I am getting about 12mpg city and 18mpg highway, and it’ll chirp new 35” K02s in 2nd gear, so I’m gonna cross my fingers and hope for the best for now.

 

[MTF]

I want to add some more things for you to check.
Check for corrosion of the pins in the connections for the Throttle body and......
Most importantly check the three PCM connections and I mean both sides of the plugs.
While the pins may look good, you need to open the back of the plugs and check the wires going into the pins.
Somebody on here had this problem and did a little write up on how to open check in there.

Ford does a real crappy job of taping up the loom to the plugs!!!

I would also check the starter terminal cables. there could be corrosion between the cable eye ends.

 

[2011reptar]

I want to add some more things for you to check.
Check for corrosion of the pins in the connections for the Throttle body and......
Most importantly check the three PCM connections and I mean both sides of the plugs.
While the pins may look good, you need to open the back of the plugs and check the wires going into the pins.
Somebody on here had this problem and did a little write up on how to open check in there.

Ford does a real crappy job of taping up the loom to the plugs!!!

I would also check the starter terminal cables. there could be corrosion between the cable eye ends.

Thank you! I’ll check all of these tomorrow. I did have an older 06 4.6 f150 that had a failing PCM from corrosion, could definitely be an issue again.

 

[Canuck714]

Check all the grounds... there are a ton of them..
Worst offender is under passenger side door where it goes from frame to body. Them look at all the grounds in engine bay and also on the BCM in kick panel.

 

[OrangeRap1]

I had a ford 351 doing what you described and it was the timing chain tensioner.