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Car kicks/jerks arounf 30 mph

BE6Pony

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My 2015 Auto 5.0 does this too. It actually got really bad recently. Interestingly I took the sound tube off my CAI and capped it off and now it doesn’t seem to jerk much anymore.
I think the fuel cutoff thing you are talking about is in all of the cars. I’d bet it is coded into the ECU.
You should take a picture of the tube you capped interested so see if I do that if it would help.
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ChiTownStang26

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I think the sound tube is only on the GTs. Id love to know if one of you guys with an auto can watch the A/F and see if it goes to 20.0 simultaneously with the jerk. Wanna know if we're experiencing the same thing or if this is two separate things
 

Bluemustang

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I think the sound tube is only on the GTs. Id love to know if one of you guys with an auto can watch the A/F and see if it goes to 20.0 simultaneously with the jerk. Wanna know if we're experiencing the same thing or if this is two separate things
Ill try to check to see what you’re talking about. Mine would occur more when I’m in Sport (manual mode) - I get off the throttle and the AFR will stay at 14.0, meaning it continues to add fuel. In other words, instead of the car losing momentum with the engine braking, it actually gains or maintains momentum as the ECU is telling it to keep adding fuel. It’s almost like the ECU gets confused whether or not to go into full engine brake.

What most of you I think are talking about is just the transition from fuel cutoff to fuel adding. This I think- might be controllable in the tune and the throttle response. On a few Bama tunes I had, the transition between fuel cut off and throttle tip in which rather abrupt and displeasing. With my Lund tune it is much smoother and responsive of sorts.
 

888mustang

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Fuel cut

I am a auto tech 35+ years. All cars turn off the injectors after the car gets up to operating temp when you let off the gas,its called fuel cut. They do this for better mileage and also to give the cats a rest. If you have a manual you can feel it better if let off the gas in 2nd or 3rd gear and coast down you will feel the injectors turn on about 1200 RPMs.
 

ChiTownStang26

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[MENTION=13732]888mustang[/MENTION]

Awesome man lemme pick your brain for a min..

I see you drive manual too, do you experience the jerk also when you let off the gas and get back on it? Is it related to the fuel cut off? Or is it slop from the driveshaft? Thanks in advance
 

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s550v6

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So this may be a stupid answer/someone may have suggested it already but could it be the torque converter locking up causing the jerk? I always thought that’s what it was on my V6. I also have about an inch of play in my driveshaft that Ford refuses to fix which can make a slight jerk motion at slow speeds also. Put these 2 things together and my car is pretty dam jerky too FWIW!
 

888mustang

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No I dont get a jerk when on off the gas but there is a lot of drive line slop if your not shifting smooth.
 
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JohnnyBoy

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I'm gonna try to detune the car then put it back on and see if that'll help
 

whatdoyoufeedit?

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Um no... this is not "normal". Check your car for vacuum leaks and send your tuner a datalog to see what is really going on versus guessing.
 

BE6Pony

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Um no... this is not "normal". Check your car for vacuum leaks and send your tuner a datalog to see what is really going on versus guessing.
I find it hard to believe that it would be a tuning/vacuum issue since almost everyone that owns an S550 I have spoke to had the same issue.
 

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whatdoyoufeedit?

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I find it hard to believe that it would be a tuning/vacuum issue since almost everyone that owns an S550 I have spoke to had the same issue.
Nevermind, you're correct it was late and I read the post wrong. Yes the car just sounds like the converter kicking down (like many automatics do) to slow the vehicle down quicker upon deceleration just like it would jerk forward when downshifting a manual to slow the vehicle down.
 

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So is mine not normal? Or is it the same thing you guys are talking about with the converter kicking down when I try to accelerate?
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