[nfashfield133]

Why is my car feeling hesitant at times? I am hoping someone here has had similar issues, and can weigh in on this.

Just a quick run through of all the mods I have:
1. Pypes Axle Back Bomb Exhaust
2. Ford Performance 3.73 rear end
3. Ford Performance Traction-LOK Limited Slip Differential w/ Carbon Discs - 31 Spline 8.8 in.
4. Ford Performance Aluminum One Piece Driveshaft
5. iTSX Bluetooth Tuner ( car is currently stock however it has a 91 and 93 octane tune )

102,000 Miles on the car. Never changed spark plugs or anything in the engine. Only cleaned K&N Air Filter.

I would say it is about a 50/50 split as to how reliable the car feels under acceleration. (car does this whether the tune is on stock, 91, or 93 tune) Upon acceleration the car feels like it loses a decent bit of torque. and just does not feel 100% healthy. It is a bit hard to explain, because other times the car feels like it takes off like a rocketship at low rpm's with a decent bit of throttle.

Example: today going around a corner, I kept the car in second gear and held the throttle steady going around the corner, when it started to straighten up, I floored it as per usual. There was about a split second delay where the car hesitated then went full throttle. Keep in mind this is when the car is stock, not tuned. So I do not think the tune is at fault at all.

What is typically the direction to look when having issues like this? I have never done any engine work, and the car is over 100k miles now so I know many things could be the culprit. Just want to know where I should look first before I spend money in the wrong areas.

 

[Bullitt95]

The obvious thing to do is to replace the spark plugs. You should replace the fuel filter as well if that's the original.

 

[JBert]

yeah might be some basic maintenance needed . . .

or, it might be the traction control kicking in. If you are getting a little bit of wheel spin under some conditions, then the system could be sensing that and cutting power, because that's how it works. Try turning traction control off as a routine and see if it still does it.

 

[Beechkid]

and if after all the above there are still issues, dump the K&N filter and replace all the intake sensors and MAF...likely an oil contamination related issue (well known for decades). Although some do have success cleaning them, just as many do not and given the age of the vehicle, probably should replace anyway.

 

[kevstang]

Also clean the throttle body. I saw that mentioned on here a few years ago and I tried it on the 07 GT I had
at the time with about 45,000 miles and it took care of my hesitation problem.

 

[marylandGT]

So you're saying it does this weather it's the stock tune or the other octane tunes. Correct?
The 05-09 4.6s have been known to have that lag while running stock tunes because it's no longer drive by wire. There's a sensor from the gas pedal that talks to the throttle body.
A good tune should eliminate that.
All your mods are for underneath your car. Maybe these guys are right about getting your engine squared away.
Start with your air intake. Clean the filter. Clean the maf, with the correct spray. Clean the throttle body, with the correct spray. Check the plugs.
Btw, are you the original owner? You say 102k miles and never changed plugs or anything else.

 

[nfashfield133]

So you're saying it does this weather it's the stock tune or the other octane tunes. Correct?
The 05-09 4.6s have been known to have that lag while running stock tunes because it's no longer drive by wire. There's a sensor from the gas pedal that talks to the throttle body.
A good tune should eliminate that.
All your mods are for underneath your car. Maybe these guys are right about getting your engine squared away.
Start with your air intake. Clean the filter. Clean the maf, with the correct spray. Clean the throttle body, with the correct spray. Check the plugs.
Btw, are you the original owner? You say 102k miles and never changed plugs or anything else.

Yes it is the same if it is tuned or stock. I think it is most likely my plugs or a dirty throttle body because I have never touched them.

I got the car when it had like 55k miles. Not sure what work was previously done.

 

[JKrew]

You should definitely change your plugs. Even if that wasn't causing the issue, it is time for them to be replace. I had similar symptoms when one of my spark plugs went bad, so that could be the issue for you too. Like Bullitt95 said, change your fuel filter if you have not done that lately as that's another easy replacement.