GEN 2 Engine stumble under light boost on freeway - code P0301

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91Eunos

91Eunos

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Swap coils with another cylinder and see if misfire moves to other cylinder. if it does it is the coil that's bad , if not could be a injector .
Yup, that was going to be my next step if I couldn’t find one in stock reasonably close by. A 1.5 hour drive each direction, but got the only one in San Antonio this afternoon… so much for reloading some 6.8 cases, and maybe even getting out to the range to enjoy this awesome weather we’re having today :-/

Regardless, removal of the old coil and installation of the new one went without a hitch, and the truck is running as smooth as ever.

Took me as long to get the engine cover off as it did to swap the coil, LoL.

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Will see how it runs the rest of the week…. No news will = gtg!
 

pavendort

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I had this problem about a week after buying my 17 used. Apparently "a rat chewed through a wire harness on the back of the engine" was their official cause. I believe it was an injector harness. Extended warranty refused to pay for it due to it being from animal damage, but the dealership ended up eating the cost as it was already damaged when I bought the truck.
 

Gen1TillDeath

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2 different schools of thought I guess… but in that case, i would rather deal with swapping plugs earlier, rather dealing with a seized one later.
 

Ellison3

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Everything you described sounds exactly like what happened to me. What I ended up finding to be my issue was a MAP sensor covered in an oily/ watery substance.

Cleaned it off, and performance returned to normal; for about a week. Next, I tapped a small hole in my intercooler. I got at least a 1/4 cup of dirty oil/water mixture that leaked out.

Originally installed a Full Race oil catch can which fixed this issue. Can caught that contaminated mixture before it got to the intake. Then, replaced the OEM intercooler for Full Race’s Freak-O-Boost kit. When I removed the OEM intercooler it had oil residue one side and water/ gas residue on the other (see attachments). The TurboSmart BOV took care of the contaminant issue; took the catch can off as it wasn’t collecting anything at this point (nothing drained in over year after BOV installed).

Still have the catch can and CAI if anyone is interested. Had it in my Expedition, but meant for you F-150 guys. Works great with stock system. Have no complaints. Once I upgraded the intercooler and BOV it remedied the issue before the catch can could do it’s job. Figured I’d take it out the PCV loop to prevent the added flow space from becoming a point of PCV pressure failure.

Maybe try pulling that sensor (on top of your intake manifold) to check for residue. It’s easy to check. Spray some MAF sensor cleaner on it if it’s dirty and take the truck for a spin. See if it makes a difference. Made all the difference in the world when I did it. The sensor, and throttle body were nasty. ***Disclaimer: Do not actuate the throttle body butterfly manually when still connected to the vehicle harness!!! Remove the throttle body harness before manually moving the butterfly. Failure to do so could cause failure of the throttle body. Vehicle will lose ability to read position, thus causing a “limp mode”/ CEL response due to loss of throttle body/ accelerator calibration, or movement synchronization.
 

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hingedthinker

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Glad I found this thread. I have new to me 2018 Rap for four days. Love the truck and no issues except the one described here in OP. On WOT from stop or highway at 80 to WOT I get a very noticeable engine shudder, almost like the ecu cutting fuel on/off quickly. This morning I tested and replicated again. Noticed transmission stayed in 7th gear but still shuddered. Feels like the engine not the transmission.

Ellison fixes seem reasonable other than the costs of those parts. Does my description sound familiar?

thinking i will start with new plugs, boots and coils. then catch can, new thermostat.
 

Ellison3

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Yes… very familiar. That’s when I experienced my issue; at WOT on the interstate. Normal driving, that is to say, gradual acceleration would not render the stumbling results. But, as soon as I would put it to the floor… bam!!! She’d **** all over herself. CEL, limp mode, etc.

As far as the plugs I wouldn’t change them; at least not until you’ve remedied the oil blow-by issue. You’ll just end up ruining the new plugs; almost immediately. Do the other stuff first, then get the plugs taken care of. Just my opinion. Feel like you’ll be wasting time, and money.

Check those sensors… especially the MAP sensor. If it’s nasty you know you’ve got condensation in the intercooler being through. Being four days old I’m 100% sure the previous owner experienced the same issue.

If you don’t want to spend a lot of money I’d suggest cleaning the sensor, tapping the intercooler to drain the fluid. At which point you’d want to get a catch can to prevent it from happening again. Which catch can you go with would be up for debate.

As I stated before I went with the Full Race setup. Absolutely loved it as it did a great job, and looked good doing it. It is pricey in comparison to others. When I did the Full Race intercooler with the TurboSmart BOV it made that catch can null and void as the BOV remedied the issue before reaching the catch can.

I haven’t had any further issues of that nature after the mod. Good luck with your fix.
 
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