I have a few hundred miles on my 2014 Mustang GT Premium (w/ Track Pack) manual transmission and when I'm driving between 20 to 40 MPH on a flat or slightly downhill street it’s difficult to hold it at an even speed - the engine bucks or surges. It’s like if you press on the throttle then off throttle over and over again. It’s getting annoying. I read one post about cleaning the MAF with special spray - which I did, but still surges around that speed. I've also tested it at different RPM's (ie 2200 thru 3500). When I'm stopped at idle it sits right at 800 RPM or if I'm constantly pressing on the gas its fine. Its when trying to hold it at an even speed around 20 thru 40 MPH that it surges.

>> Any ideas or thoughts?

 

Hmmm this is the first I've heard of this. Is the cruise control engaged when you see this? Or is this actually happening when you are trying to maintain a constant speed with the gas pedal?

 

I have felt something similar when trying to stay around 3k, I also talked to a few guys who feel something similar. I wouldn't consider it a surging but it somewhat feels like the cam timing is trying to change back and forth.

 

Nope Cruise Control is not on at all.

>> I think this might be related to manual transmissions, because it is like when your on the gas pedal the gears and clutch and engine are on power or torque - but at a certain speed it toggles or see/saws back and forth with engine torque.

 

Use a low gear and keep the rev's up when going slow it stops the cam from adjusting back and forth or 6th and cruise on.

Sounds silly but I have numerous school zones and residential streets with 20 MPH restrictions and it's a pain to keep within that speed unless I either let the engine rev and keep it in 4th or cruise control in 6th and just let it "chug" along.

 

Are you driving too slow for the gear you are in and maybe lugging the engine?

 

I wouldn't think cleaning the MAF would be necessary with only a few hundred miles on it. Are you referring to "a slight surge" or "massive bucking" where you feel and hear the definite on and off again?

I have felt some slight surging but, like you, I only have 255 miles on the car. I get a surge or stumble starting in 1st gear from a stop. Car bucks just as clutch is nearly out all the way, but it might be me getting use to it..not sure. I am going for a ride today so I will pay more attention and post a note here.

 

Hey guys,

I recommend you bring your vehicles in to your Ford dealers and have them check it out. Then, PM me with your VIN, dealer, mileage, full name, and best daytime number so I can escalate this to the customer service manager for your area.

Deysha

 

Deysha, Thank you either Saturday or Monday I'll take it into the Dealership and PM you with the info. Plus, I wanted to reach out to "The Mustang Source" community and see if others had simular situations or solutions....

 

No problem! I'll be waiting on the info.

Deysha

 

Just returned from a ride and tried to duplicate the problem you are having. While I did notice very slight surge it wasn't terrible. I might not have noticed it if I hadn't been trying to duplicate it. There are a lot of variables though, speed, gear etc.

 

Noticed it once in my Track Pack tonight. Engine was still cold... Just left the house. Shifting from first to second around 3000 RPM. The car lurched once. I attributed it to letting off the throttle too long before pressing in the clutch. Would not have noticed at all if not for this thread. My passenger (A Tech) did not notice at all. Think it is normal... But may not have experienced exactly what you have occurring.

 

I have had this problem a couple of times but mostly due to the car being cold and the clutch and driveline "give" due to the two piece driveshaft. If feels like the car is bouncing back and forth within the give. Pushing the clutch in and then using much more gas usually does the trick. Never had it happen when just cruising along. Just when I am just getting going and not using much gas.

 

I think both of you 14Glassback & Stevedotmil are describing the same issue I've felt. The surge occurs when your trying to keep a slow speed but your on and off the gas and/or the tourque of the engine. I've tried shifting gears up or down with different RPM's but it continues. Also I live up on a hill and drive 15 minutes on a slight downhill on city streets (40 MPH) to get to the freeway. This is the perfect condition to expeirance the surge.

 

Hi guys,

I recommend you all make an appointment with your dealers to get them checked out. Then, PM me with your VIN, dealer, full name, mileage, and best daytime number so I can escalate this to the customer service manager of your areas.

Deysha

 

For what it is worth, my 2010 F-150 will do the exact same thing around 30 MPH. 4.6 3 valve engine. Done it since new. The dealership could not figure it out. Not really bad, just noticeable. You can see the tach move up and down slightly with the gas pedal held steady. The mustangs in the past I have had, I did not notice it.

 

I get this "surging" to often going around 10mph in first gear. The car bucks a bit but once i get moving its fine. I believe this was due to the engine not being fully warmed up and me driving wayyy slow and kind of giving it to much gas then letting off then more gas etc creating a rise is rpms then decrease. I havent noticed in any other gear or at higher speeds above about 10 mph. I have 3.73s btw so 1st gear is almost non existent lol.

 

I've had this issue with both my 2011 5.0 and now my 2014 roush s2. The dealer tells me that it is normal
The surge that is not being explained here is ;
No matter cold or hot the engine will surge between 2k -2500 rpm as you level out no matter what gear mine has the MT82 trans but it feels as if (like on an automatic) goes in an out of overdrive.

Other issue is tick after first oil change done by dealer dealer says this is normal(sounds like a lifter taping or clutch disk damping springs be loose in their cage). Thanks.

Edit. Im to the point to where I will say forget the dealer and make the repairs myself. Fed up with the run around of in competent techs (parts replacers)

 

Now that I'm off my rant. Lol
It seams that there is no solution for the issues we are having.

Is there a chance that the trouble maybe the electronic throttle tolerances in the gear within the housing having to much play?

 

With 2500 miles on my 2014 now, this condition you all describe has been there since it rolled off the dealers lot. ( The stumble at the end of the clutch engagement in first gear, lurching in the lower gears at low rpm, etc ). I realize I will draw some fire over this statement, but I'm convinced this is all a result of throttle by wire calibration thru the ECU from the factory. The on again, off again throttle response at lower speeds seems to indicate that the computer can't seem to properly regulate the amount of fuel flow needed for a particular situation. To compensate, as suggested by others here, keeping the rpms up in a lower gear is what we are going to have to live with. Others on this site have indicated that a proper tune will help this issue considerably. If so, that tends to reinforce my thoughts on the factory calibration of fuel flow mapping. Just one man's opinion.