Funky Hesitation Under Load... Help!
02-16-2011, 03:56 PM
#1
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Join Date: Dec 2009
Location: Florida
Posts: 100
Funky Hesitation Under Load... Help!
Here's my issue and I can't figure it out for the life of me...
When zooming along on the interstate, if I downshift and then step on it I get a really, really bad stutter and then it goes fine. It feels like the engine just stops for a moment. Or like you are taking off from a stop in first and don't give it enough gas and then floor it.
I can't figure it out. It is especially bad downshifting into third and mashing it exiting the interstate (I love zooming down the ramp).
It runs great otherwise, and it doesn't do it upshifting.
On a second note, will hitting the rev limiter do any damage? I assume that is why it is there, but I ran into it the other day (I've been driving an auto for a year and "forgot" to shift).
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2006 GT 5 speed with 15,000 miles.
When zooming along on the interstate, if I downshift and then step on it I get a really, really bad stutter and then it goes fine. It feels like the engine just stops for a moment. Or like you are taking off from a stop in first and don't give it enough gas and then floor it.
I can't figure it out. It is especially bad downshifting into third and mashing it exiting the interstate (I love zooming down the ramp).
It runs great otherwise, and it doesn't do it upshifting.
On a second note, will hitting the rev limiter do any damage? I assume that is why it is there, but I ran into it the other day (I've been driving an auto for a year and "forgot" to shift).
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2006 GT 5 speed with 15,000 miles.
Last edited by HeadonaStick; 02-16-2011 at 03:58 PM. Reason: Note car info
02-16-2011, 04:25 PM
#2
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Join Date: Jul 2006
Location: New Orleans
Posts: 4,491
Fuel pump TSB. Hesitation after cruise. http://www.themustangsource.com/gala...hesonaccel.pdf
Last edited by Diabolical!; 02-16-2011 at 04:28 PM.
02-16-2011, 05:00 PM
#4
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Join Date: Dec 2009
Location: Florida
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Well, that clears that up. How difficult would it be to replace the fuel pump? Right now it is under a 50/50 warranty but I'd prefer to do the work myself is possible.
As for the red line, that's about what I figured. I actually shift before red line but I was having a "spirited disagreement" with another car and took off - forgot about shifting (I know, it sounds stupid but hey, that's the truth) and was into the limited for probably 3-4 seconds trying to figure out why my car was acting goofy - and then felt like a fool. And then assumed my engine was one turn away from total failure...
Still came out on top of the spirited disagreement, but it wasn't nearly as tragic for the other guy as it should have been...
As for the red line, that's about what I figured. I actually shift before red line but I was having a "spirited disagreement" with another car and took off - forgot about shifting (I know, it sounds stupid but hey, that's the truth) and was into the limited for probably 3-4 seconds trying to figure out why my car was acting goofy - and then felt like a fool. And then assumed my engine was one turn away from total failure...
Still came out on top of the spirited disagreement, but it wasn't nearly as tragic for the other guy as it should have been...
02-16-2011, 05:46 PM
#6
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Join Date: Jul 2006
Location: New Orleans
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Worth a shot, but they probably won't cover you. In any case, changing the fuel pump is simple. You have to pull out the bottom portion of the back seat. If the new fuel pump does not come with a new lock ring and gasket for the fuel tank, then you will want to buy those as well (cheap stuff).
The fuel pump is located on the driver's side under the rear seat. There is a black rubber boot covering it. Remove it. Then remove the fuel line from the top of the fuel pump and remove the lock ring and gasket. Next, disconnect the line that is connected inside the tank (a bit tricky, but you'll get it). Install is reverse of removal.
The fuel pump is located on the driver's side under the rear seat. There is a black rubber boot covering it. Remove it. Then remove the fuel line from the top of the fuel pump and remove the lock ring and gasket. Next, disconnect the line that is connected inside the tank (a bit tricky, but you'll get it). Install is reverse of removal.
02-16-2011, 06:18 PM
#7
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Join Date: Dec 2009
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Thanks for the help... one last question: How do I relieve the pressure in the fuel lines, and do I need to prime the system when I'm finished or will the FI pressurize the system itself?
I'd prefer not to get a 91 octane shower
I'd prefer not to get a 91 octane shower
02-16-2011, 08:03 PM
#8
I would agree that it could most likely be the fuel pump TSB. Another idea could be DBW throttle lag if you're completely stock. The stock tune does not allow Full TB butterfly opening when floored, they open 85% and then slowly go to full open. You may be experiencing this.
02-16-2011, 08:14 PM
#9
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Join Date: Dec 2009
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I would agree that it could most likely be the fuel pump TSB. Another idea could be DBW throttle lag if you're completely stock. The stock tune does not allow Full TB butterfly opening when floored, they open 85% and then slowly go to full open. You may be experiencing this.
Still needs a tune - my 08 with a tune and CAI responded like a totally different car than this one. Gotta get it running right first though...
02-17-2011, 07:36 AM
#10
6th Gear Member
+1 on the fuel pump TSB. One other item that occasionally screws with going WOT and causes hesitation is the TCS. Turn it off. But I suspect your isssue is the fuel pump.