Misfire only 6th gear.

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jg1337

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2012 Roush charged and loving it!

Only problem is I experienced a huge misfire in 6th gear when getting on the highway, if I manual shift the trans above 2200 RPM no issues, if in full auto mode and in sixth gear it will violently shake and misfire. The check engine light will come on and Fash but as soon as I drop the trans in M and kick it down a few gears everything clears ups the check engine light turns off. I tried to run the code with my cheapo scanner however it shows Zero codes (assuming the codes don't get stored, or the Scanner can see stored codes). I just purchased MAF cleaner and figured its due for plugs/coils and wires at this point. The gas tank was 3/4 when this happened, and I've since refueled and put a bottle of dry gas in it. As a precaution I purchased a valve spring, figuring ill pull the valve covers off when I do the spark plugs/ wires and coils and inspect for any damage.

any experience or impute on this from long time owners??
 

FordTechOne

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High load/low RPM misfires are usually ignition related. The flashing check engine light means it’s a catalyst damaging misfire, so you don’t want to continue driving it in that condition.
 
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jg1337

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When it happened, I was in heavy traffic and attempted to limp it into the BDL, by the time the BDL opened up the misfire had cleared, and the light was off so I just continued home with no further issues (Trans remaining in M).

Do you think I should keep driving the truck in M? or deadline the truck all together?

I also contacted a tuner to dyno the truck once I change out the Plugs/wires/coils.
 

FordTechOne

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I would avoid driving it if possible. But if you have to, try and avoid the conditions that cause it to start misfiring. Be sure to get Motorcraft coil/plugs/wires.
 

Marlboroman

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All my older f1shittys displayed the exact thing. Classic case of ford plug/packs being worn out or damaged. Fortunately ford got the plug threads right on the 6.2 I’ve never had an issue changing them.
 
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jg1337

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Update:
I've cleaned the MAF sensor and replaced 14 out of 16 sparkplugs (6510) and gapped them all to .030 I also replaced 14/16 coil (NKG) packs and wires (MSD) however I could not access the top sparkplugs on the #5 & 7 cylinders. Does anyone have any tips on removing the intake runner to the TB on the Roush r2300 supercharger.

The forward two most bolts I was able to loosen however I could not get to the rear???

The plugs I removed were gaped to .045 or so and were in very rough shape.

The problems I've been experiencing seem to be gone!

**Also, to everyone who posted the How-To on sparkplug replacement. I am 100% great full!!!**
 
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jg1337

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Does anyone have any tips on removing the intake runner to the TB on the Roush r2300 supercharger.
Anyone?
 

roush_14

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Remove 2 forward bolts. Use 1/4 drive swivel socket and short extension, and swivel head 1/4 rachet to get at back ones , you only have to loosen them about half way, the holes are slotted on the back 2 mounts on throttle body elbow it will slide forward. And a lot of patience.
 

Canuck714

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The elbow is a PITA, but follow roush_14's instructions, you don't need to completely remove the back bolt.

My 14 Roush was literally a month old when it did something similar. Got a JDM tune and presto...Ran 120,000 miles without it ever doing it again!!
Get a tune from JDM, run good gas and I bet you will not see that issue under the same circumstances.

This is problematic with a Roush tune as Roush does not re-write the trans tune to go with their ridiculously over fueled/over timed ECU tune.
So what happens is the trans refuses to be in the correct gear while you are building boost and fueling the shit out of it at low RPM. This creates tremendous cylinder pressures and the ignition cant keep up.
Did it still have the factory spark plugs in it when you swapped to the cooler 6510? Roush doesn't bother to swap those stock heat range plugs out either and is a bad idea for a boosted application.
You may have experienced pre-detonation more so than a misfire if still on stock plugs/stock tune.

Hope you get it all sorted out, once they are dialed they work really good and are reliable. I pounded on mine and never had any issues once i set it up right.
 
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jg1337

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Canuck, it did have the 6510's when I swapped them out, they were however gapped at .045 or so, they looked as if they really needed to be changed. The previous owner stated that he changed them at 150k or so, current milage is 190k but he said that the truck sat for a few months (and is shows).

Roush14, just so I'm getting this right, an 8mm then a swivel, small extension and then another swivel all in 1/4 drive?

Thanks again for all the replies!
 
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