Slight surge after letting up on throttle

[tw557]

I just picked up this ecoboost about a month ago. I have noticed that at low to mid rpms when I let up on the throttle the car slightly surges or more so hangs for about a half second or a little more then starts to decelerate. Is this just normal? I didn't notice this on my other turbo Audi car. The car came with magnaflow exhaust, Catted downpipe (can't tell what brand), and MAP CAI. I have since put back on the stock air box with no change other then a whole lot quieter. Thanks.

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[cthomas5714]

I feel like there is always a little slop in the driveline with certain cars in specific gears. My car will only do that when I have it in sport mode and I let off the gas sitting in first or second gear though.

 

[Nick@JDM]

I just picked up this ecoboost about a month ago. I have noticed that at low to mid rpms when I let up on the throttle the car slightly surges or more so hangs for about a half second or a little more then starts to decelerate. Is this just normal? I didn't notice this on my other turbo Audi car. The car came with magnaflow exhaust, Catted downpipe (can't tell what brand), and MAP CAI. I have since put back on the stock air box with no change other then a whole lot quieter. Thanks.

There is usually a programmed delay as the car enters coasting fuel shutoff and begins to decelerate. This is done to make the transition less noticeable to the driver and or to smooth the the transfer from quick on/off throttle conditions. There is also usually a torque ramp out rate to control how quickly power comes off as well as how quickly the car decelerates.

I speak loosely about this since I have not looked at an Ecoboost Mustang file in depth but have so with the twin turbo F150s.

All of this can be tailored in a custom tune to your liking and I am sure Adam at Tune + can help you with more info on this.

 

[tw557]

I so want a custom tune and the cost would be fine but i had to go and buy a CPO MUSTANG and just can't bring myself to throw the drivetrain warranty out the window especially since used engines and transmissions are not too cheap yet. My audi before this had a custom tune and it was incredible. The surge is a little annoying though.

 

[Nick@JDM]

I so want a custom tune and the cost would be fine but i had to go and buy a CPO MUSTANG and just can't bring myself to throw the drivetrain warranty out the window especially since used engines and transmissions are not too cheap yet. My audi before this had a custom tune and it was incredible. The surge is a little annoying though.

Completely understand. Are you sure that he car doesn't already have some sort of flash on it already?

If I found a car hat already had those modifications to it I would be suspicious that is was tuned or once had a tune in it and was returned to stock before it was sold.

 

[tw557]

I was suspicious of the tune also and mentioned my concern to the dealership when purchasing. They assured me that it would not have been certified if a tune was present. I then also have an email from them stating that during the certifying they replaced a coil and updated the computer to fords latest program for the car so that it is definitely stock. I drove other cars during my search and didn't detect any performance gain with this car and if anything I thought it ran slightly worse then the stock ones. Hearing all the turbo hissing and blowing and the exhaust resonance that just didn't sound smooth could have been my imagination of performance loss though. But thinking back I don't remember the comparison related to the little surge I am talking about hear.

 

[sauerkraut]

Hold on, it has an aftermarket downpipe, but a stock tune.

The dealership should have known better....or they are lying. Have any CEL's popped up?

 

[tw557]

It is a catted downpipe but no CEL's. I'm certain there is no tune now as I don't see high boost and nothing feels too strong and in the Ford system it shows that the latest ford program was uploaded during the certifying process.

 

[DUNDEM]

I was suspicious of the tune also and mentioned my concern to the dealership when purchasing. They assured me that it would not have been certified if a tune was present. I then also have an email from them stating that during the certifying they replaced a coil and updated the computer to fords latest program for the car so that it is definitely stock. I drove other cars during my search and didn't detect any performance gain with this car and if anything I thought it ran slightly worse then the stock ones. Hearing all the turbo hissing and blowing and the exhaust resonance that just didn't sound smooth could have been my imagination of performance loss though. But thinking back I don't remember the comparison related to the little surge I am talking about hear.

Glad you got the the letter. I guess a catted downpipe doesn't need a a tune. I thought down pipes required a tune. Maybe Ford flashed it stock then sold it.

 

[DUNDEM]

I get the thud as well by the way. Going to change the gear oil for piece of mine soon.

 

[tw557]

Actually luckily I get no thud or noise at all. It just has the feeling of no reduction in speed for a half second after leaving off the gas. Mostly at lower to mid rpm. Almost in sync with the blowoff I heard thru the loud MAP intake.

 

[RubyRedBoost]

Ford wont certify a car with aftermarket modifications. I would look for your warranty paperwork. Sounds way too sketchy to be legit. A lot of dealerships claim vehicles are certified pre owned but never pay for the certification through Ford. Or include such paperwork with the vehicle.

 

[tw557]

I was thinking the same thing but they assured me that they can. I have lots of paperwork with certified pre owed info. I also emailed ford corporate and got this partial response
The installation or use of any aftermarket product will not necessarily void the New Vehicle Limited Warranty or Ford Certified Pre-Owned Program (CPO) warranties. However, if the aftermarket product fails or causes a Ford Motor Company part to fail, the cost of the repair and any related damage(s) are not covered by your Ford Motor Company warranty.

I wouldn't doubt they missed the downpipe. It is a very large dealership.

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