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engine stumbling

Has anyone had an issue with acceleration stumble from 1st to 2nd gear at mid range rpm? Engine seems to go flat, then catch and go......but intermittently. Also, on the highway at 70 mph without cruise, take foot off gas to slow for traffic or downhill, then when pushing back on gas pedal, engine lurches momentarily.....does NOT occur when using cruise control under similar conditions!
Could this be a dead spot in gas pedal rheostat? I've not had a check engine light come on in either case. Hate to take to dealer with no c/e light.
Any feedback would be helpful.
Thanks,
Ron :-\
 

TMSBOSS

Spending my pension on car parts and track fees.
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bullitt said:
Has anyone had an issue with acceleration stumble from 1st to 2nd gear at mid range rpm? Engine seems to go flat, then catch and go......but intermittently. Also, on the highway at 70 mph without cruise, take foot off gas to slow for traffic or downhill, then when pushing back on gas pedal, engine lurches momentarily.....does NOT occur when using cruise control under similar conditions!
Could this be a dead spot in gas pedal rheostat? I've not had a check engine light come on in either case. Hate to take to dealer with no c/e light.
Any feedback would be helpful.
Thanks,
Ron :-\

If you have not modded the engine the issues should be covered under warranty.

Several people have stated that Dealers are the last place they want to take their car. During the warranty period they are the first place we should consider. If for nothing else, to document the issue.

Good luck with your troubleshooting.
 

steveespo

Lord knows I'm a Voodoo Child
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I agree with TMS, take it to the dealer. If you have done a tune/CAI switch back to stock to check for problems with that mod. If that doesn't cure it the dealer mechanics will be better able to run the Ford diagnostic protocols without worrying about changed parameters in the tune or aftermarket intakes messing with the MAF readings. If the car comes back clean from that then you could reinstall mods and tune to ensure there are no vacuum leaks etc.
Steve
 
The only mods are the factory track key and the side exhaust electric cutouts, so it has to be a factory warranty issue. Being intermittent, it's hard to duplicate, so maybe a scan may show something.
 
Mine will surge/lurch if I start driving before allowing the engine to warm up for at least 1 minute. Some glitch in the part of the program that raises the idle rpms on startup is my suspicion. She will lurch forward when I start to brake while in gear. Scary for me and the pedestrians I was stopping for one of the times it happened.... But that problem is consistent and easy to reproduce and avoid.

Ford is proving to have crap software engineers recently (don't get me started on my Focus), and your engine is completely fly-by-wire now... If your problem is unrelated to software then I will stop giving advice completely.
 

Justin

Save the dawn for your dishes!!!
Maybe you are referring to the "trailer hitching" feeling most of us noticed with ford factory tunes. If so this is normal. Cure is a tune from AED :)
 
bullitt said:
Has anyone had an issue with acceleration stumble from 1st to 2nd gear at mid range rpm? Engine seems to go flat, then catch and go......but intermittently. Also, on the highway at 70 mph without cruise, take foot off gas to slow for traffic or downhill, then when pushing back on gas pedal, engine lurches momentarily.....does NOT occur when using cruise control under similar conditions!
Could this be a dead spot in gas pedal rheostat? I've not had a check engine light come on in either case. Hate to take to dealer with no c/e light.
Any feedback would be helpful.
Thanks,
Ron :-\

FWIW, initially I had intermittent stumbles when shifting from 1 to 2 at roughly 3750-4000 rpm. Then the issue started to occur at different rpm's and gears. There were no codes stored. In my case the dealership had to hook up the VCM II flight recorder and drive the car more than 5-10 minutes to "capture" what was occurring. They were able to pin-point the throttle body as the culprit and replaced the T.B. under warranty. This solved my issue.

My 2012 boss was and still is stock.
 
Mine does this too. I am going to take mine in soon to be looked at as well.

OP if you figure out what your issue is, please keep us updated. I'd love to have mine fixed.
 
Thanks to all for feedback! Will get into dealer for wring-out soon. Never had an issue with our GT500 or '03 T-Bird, as far as drivability issues are concerned. 8)
 
Had stumbling issue checked at dealer -- could not duplicate and flight recorder showed zip,nada.....! That was couple weeks ago and car has run perfectly until yesterday -- on Telegraph Rd. cruise! Pulled away from a turnaround and got some revs up, engine hesitated on 1-2 shift again, then fine rest of day! Plan to take in again soon.....the saga continues!
 
I've had stumbling issues since day one. Took it back in a couple of weeks ago, and had the drivability expert road test it with the laptop....told me that there is a very small amount of misfire.....but that it is within acceptable range. Something called a mode 6 diagnostic. The service manager and writer were completely useless. I need to elevate my complaint to corporate.
 
I got a call from dealer today to bring car in again. They must not have liked my survey answer! We'll see what transpires....will keep you all informed!
 
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3
Oddly and probably wont make sense, but I have noticed this too. But if I take off advancetrak by pressing on the brake and holding the advancetrak button down for 5 seconds, it seems to dissapear. I know they are unrelated but it seems it never occurs with advancetrak off.
 

Tucson 302

2013 Black LS #439
johna said:
Oddly and probably wont make sense, but I have noticed this too. But if I take off advancetrak by pressing on the brake and holding the advancetrak button down for 5 seconds, it seems to dissapear. I know they are unrelated but it seems it never occurs with advancetrak off.

Avancetrac is an evil thing! Have it tuned out ASAP!!
 
johna said:
Oddly and probably wont make sense, but I have noticed this too. But if I take off advancetrak by pressing on the brake and holding the advancetrak button down for 5 seconds, it seems to dissapear. I know they are unrelated but it seems it never occurs with advancetrak off.

Seems to make sense since it can mess with throttle.
 
??? 8)Took Boss back to dealer today.....they called ME to bring for a second attempt at correction! As of 4:00 PM, they have tried twice to repeat issue, one with tech & once with svc. mgr., with no stumble. Ford Tech line was called and they are waiting for reply.....keeping car indoors overnight!
When I get Boss back, will try disabling advance-trac. Have not noticed when using track key, but have used very little, and issue is intermittent:(. Will keep you all posted!
8)
 
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0
One thing I did notice is hesitation on acceleration in higher gear, usually 5th gear. When I am driving and want to accelerate, the car momentarily has a rumbling feeling as if the car is resisting power being put down but then it goes away. Almost sounds like a rear-end rumble/grind. I have noticed this in 4th 5th and 6th, but mostly in 5th. This is during regular driving and not WOT.
 

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