Got 99 problems and my Gen 1 is 1

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2011reptar

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*Updated 11/12/24*

Hello everyone! I’m Jay. Apologies for the very long first post. My Raptor is a 2011 6.2 with 110k. Bought from the original owner with full service records showing 6k oil change intervals and all suggested maintenance performed. Literally does not have a single scratch on it.

I am having an issue that I just can’t figure out. I have Forscan and am somewhat mechanically inclined having built 351W and LS motors in the past.

Symptoms:
1. W/ AC off. Non steady idle in park. Can see tach needle moving and Forscan shows 575-635rpm fluctuation and can feel the cab shudder like it’s missing.

2. Idle dips to 450rpm about every other time when put in park, almost stalls, then goes back to an unsteady 600rpm. To be clear, not when coming to a stop, specifically when putting it in park after a stop.

3. Can hear occasional popping sound from driver side exhaust area when driving or at idle. Maybe excess unburnt fuel?

Data:
1. Forscan showing RPMs fluctuate between 580-640 at idle.

2. Forscan showing long term fuel trims of -2, to -5 at idle.

3. No DTC or other irregular info that I can see.

What has been done so far:
Fired the parts cannon full blast, all OEM parts from dealer. Changed 16 plugs, 8 coils, 8 wires, 8 injectors, MAF Sensor, purge canister, PCV Valve, air filter, throttle body, up stream 02 sensors. Put seafoam in crank case, used can of spray gumout foaming cleaner on intake for valves. Pulled valve cover to inspect valve springs and guides, checked for vacuum leaks and cracks in the intake and all looks great. Compression check turned out great, PCM relearn process performed a few times. Scoped cylinders, all looks fine.

Additional information:
No engine lights, no performance issues. Fuse 27 relocated. No MPG decreases. No ticking or knocking. I run 91 octane. Brought to two shops, first said it’s normal for the “aggressive cam profile of the Raptor,” the second said maybe dirty valves but they’re unsure.

Need some help please!
 

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rschap1

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Been to the dealer and they aren't coming up with "fixes"??
With so many common repairs already done, my next guess might be taking a look at #6 valve spring(s).
Only other common issue I can think of hearing about that hasn't been addressed already.


Sorry just read closer and see that you already looked under the valve covers.
 
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dj30417

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I’m not a mechanic.

Unfortunately, there are a lot of bad parts and any one or several that you have just done could be bad.
Also, look at the O2 sensors as just one more easily replaceable part.
Good luck and keep us updated.
 

smurfslayer

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do you have a what seems like a flat spot off idle?

I had an older Mustang that had a -relatively- rough idle. Smooth by old car standards, but definitely not right for a 1997. And there was a flat spot off idle through about 1800-1900 rpms. after that it seemed fine.

After much delay, the problem turned out to be a defective cam chain tensioner. Replaced and ran as good as new.
 
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2011reptar

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do you have a what seems like a flat spot off idle?

I had an older Mustang that had a -relatively- rough idle. Smooth by old car standards, but definitely not right for a 1997. And there was a flat spot off idle through about 1800-1900 rpms. after that it seemed fine.

After much delay, the problem turned out to be a defective cam chain tensioner. Replaced and ran as good as new.
Sorta. When it idles, it’ll idle normally and every half second or so it’ll shudder. It is reproducible up to about 2000rpm and increased with rpm. Some shudders aren’t very noticeable and some feel like it’s about to die. When I monitor the RPM, it doesn’t really seem to dip much when it does it. But it does when I put it in park.
 
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2011reptar

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Something I noted today is when idling in drive, the idle seems to level out a lot. Not perfect, but less shaking, less shuddering and on Forscan the fluctuation changes to about 585-605. When put back into park, shuddering increases and idle fluctuation increases and again goes down to about 450rpm every 2-3 times it’s put into park.
 
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rschap1

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Was going to say vacuum leak(s)? But see you already checked that too.
I am all out of "easy" ideas to throw out.
Good luck and I am curious to know what you find too.
Mine has a little "lump" now and then sitting at lights, but not enough of anything for me to worry over.
 
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