Rare problem: 5th/6th gear bucking/surging and cruise control not working

[arsenalrocks]

do you have the "brake" switch part number? if so could you please share it?

Agreed. Mine was more of just a hesitation and never a surge. As if the ECU was confused with seeming random brake application (due to faulty brake pedal switch). Again, only the wrench was shown on dash with 'See Owners Manual' and no trouble code.
The Ford tech discovered the problem when doing a ride along while monitoring the car with his laptop connected, that being unexplained pedal engagement. I'm told from others that those switches, even though very critical, are oftentimes found to be faulty.

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[pbrmeasap]

do you have the "brake" switch part number? if so could you please share it?

Not sure as Max just replaced. Looks like might be FL3Z-13480-A but would get that confirmed.

 

[pbrmeasap]

Not sure as Max just replaced. Looks like might be FL3Z-13480-A but would get that confirmed.

Here is another thread that seems related. Black Boss is a respected Ford authority and also had pedal switch failure. I'll see him at Daytona in December so will be sure to bring up this problem to see if he has any additional insight.
https://trackmustangsonline.com/threads/wrench-warning-light.15109/

 

[arsenalrocks]

Black Boss wrote " I had a Wrench light and Hill Start assist caused by a Stop light switch failure (turns out the switch has two switches/circuits, one used for brake lights, the other for Hill Start/Cruise, only the latter had failed). "

that is interesting, b/c when I was cruising on the highway, it does feel like someone is feathering with the brake on/off. will talk to my shop foreman and see what he says.

 

[526 HRSE]

I spoke too soon. Definitely have cruise control working intermittently.

 

[526 HRSE]

Mine also does not have the surging. Just the hesitation. Feels like a miss or clogged fuel line. I had almost run all the e85 out and everything seemed to be ok. I just stopped and filled up with e85 again and it's very noticeable. I'll have to run this out, remove the Proflex and see if it continues. More info on the brake switch would be appreciated. Here's a photo of what the cruise does on its own when it stutters.

 

[526 HRSE]

And just like that, Check engine light goes out, cruise and A/C work again.

 

[arsenalrocks]

what fixed it?

 

[526 HRSE]

what fixed it?

no idea. I'm sure this ain't over...

 

[pbrmeasap]

Ok, am hoping I've finally and fully solved the hesitation issue, although came at a price.
Was running the car at this year's Audi Club event at Daytona Dec 11-13. 2nd session of first day. As was going through start/finish at full throttle in 5th (as normal), felt something in the drivetrain give and then a vibration begin.
Took the car straight to Ford and they eventually diagnosed as a failed clutch that then damaged the flywheel. Both were replaced under warranty. The tech also suspects that this was causing my ongoing hesitation issue. Only way to really know is when pushing it in 5th to the max, which is really only at Daytona. Will be running their again in April - so will know for sure then.
Shout out once again to Bozard Ford service for resolving the problem, all under warranty. The cost was then the lost entry fees, etc. for a 3 day event that got cut way too short.

 

[MikeR397]

Wow, well I just had a failed clutch/flywheel and trans as well to accompany the surging issue. Shitty Ford did not cover my failed clutch and gave me a bill for $2900 (I did get the parts for under half that at least). https://www.mustang6g.com/forums/th...r-clutch-in-pieces.148866/page-8#post-3096196

It’s winter in MI so I’ve only done 50 or so miles, but my car is not surging like it was before in 5th and 6th. I won’t know for sure until I can do a track day in the spring.

really pissed to hear of the unequal treatment when clutches fail. Said another way, it really grinds my gears...

 

[nordique14]

Ok, am hoping I've finally and fully solved the hesitation issue, although came at a price.
Was running the car at this year's Audi Club event at Daytona Dec 11-13. 2nd session of first day. As was going through start/finish at full throttle in 5th (as normal), felt something in the drivetrain give and then a vibration begin.
Took the car straight to Ford and they eventually diagnosed as a failed clutch that then damaged the flywheel. Both were replaced under warranty. The tech also suspects that this was causing my ongoing hesitation issue. Only way to really know is when pushing it in 5th to the max, which is really only at Daytona. Will be running their again in April - so will know for sure then.
Shout out once again to Bozard Ford service for resolving the problem, all under warranty. The cost was then the lost entry fees, etc. for a 3 day event that got cut way too short.

I would be interested to know how they diagnosed a bad clutched just based on those symptoms. I have the same symptoms. As you said, they cannot be easily reproduced and the clutch feels fine around town. So his did they figure out it was bad?

 

[pbrmeasap]

I would be interested to know how they diagnosed a bad clutched just based on those symptoms. I have the same symptoms. As you said, they cannot be easily reproduced and the clutch feels fine around town. So his did they figure out it was bad?

The drive train vibration was noticeable in all situations, even at idle. I believe they diagnosed through process of elimination (removed accessory belt to rule out ac compressor, etc.). The tech only said that he believed the clutch started coming apart, which threw the dual mass flywheel off center. Hence, they replaced both (& slave cylinder). Vibration is gone, so fingers crossed...

 

[pbrmeasap]

Quick update to report this problem continues. Have tried to run at Daytona now three separate events and all result in the hesitation problem, including check engine light flashing and then staying on with misfire codes. Ford repair attempts now include spark plugs, coil packs, crank speed sensor, tsb 18-2322. Add this to the previous brake light switch, flywheel & clutch. Have gotten the local field service engineer involved as am desperate for a resolution.

 

[MikeR397]

Wow, well I just had a failed clutch/flywheel and trans as well to accompany the surging issue. Shitty Ford did not cover my failed clutch and gave me a bill for $2900 (I did get the parts for under half that at least). https://www.mustang6g.com/forums/th...r-clutch-in-pieces.148866/page-8#post-3096196

It’s winter in MI so I’ve only done 50 or so miles, but my car is not surging like it was before in 5th and 6th. I won’t know for sure until I can do a track day in the spring.

really pissed to hear of the unequal treatment when clutches fail. Said another way, it really grinds my gears...

Have done 1,000 miles now and 4 track days since my clutch and trans were replaced. My surging issues I’ve detailed lots of places has completely vanished. No other repairs to the car, so it has to have been something in the clutch or trans causing it.

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