Got 99 problems and my Gen 1 is 1

[2011reptar]

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 shake 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?

4. No misfire counts on Forscan at idle or under normal driving conditions, but can produce a small misfire count of 10-15 per minute in Forscan primarily on Cyl 6 when holding idle at 13-1400 Rpm. Can feel the misses and hear it happening in correlation to the count increasing. Feels like the idle issue but obviously higher frequency with the increased RPMs.

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

2. Forscan showing long term fuel trims of -2, to -3 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, 4 injectors on cyl 5-8, MAF Sensor, purge canister, PCV Valve, air filter. Cleaned throttle body, 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 or cracks in the intake and all looks great.

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.

Time for a compression test maybe? It’s weird that only 1 cylinder seems to be having the issue. I am largely assuming it’s also causing the rest of the symptoms.

 

[rschap1]

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.

 

[dj30417]

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]

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.

 

[2011reptar]

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.

 

[2011reptar]

This is what I see after a 5 mile drive and idling for about 15 mins.



And this is what I see after holding the idle at 1300Rpm for about 3 mins. Nothing close to setting off a light, but clearly missing more on cyl 6. I have swapped plugs, coils and wires twice and nothing new. Lt Fuel trims as low as -8.

 

[2011reptar]

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.

 

[CleverGirl_]

@FordTechOne want to check out this data?

Mine idles funny but I keep telling myself it’s normal.