My 2007 GT (83K miles) has an interesting issue. After running errands for say half a day---multiple stops/starts--it develops a hesitation when I start it up. Can sometimes go away if I turn it off and restart..sometimes not.

I've had it tuned up recently..so new plugs (and coils are fine) and fuel filter is new....and I did have the throttle body replaced in the last 3K miles (because of this very issue).

I'm baffled Any suggestions? Someone mentioned the MAF (?)--but I not familar with this.

 

MAF sensor is in the intake snorkel. If you put in an odd filter or a CAI, then this would change how it 'felt' the air, if you will, and that will require a tune.

I assume, though, that your air filter and snorkel are stock.

Either way, it's a sensor that's mounted in the snorkel somewhere between the air filter and the throttle bodies. Only real way is to swap it and see.

Here's a picture from another website:
http://image.mustang50magazine.com/f...-for-s197s.jpg

And in it, near the cone filter, you see a protrusion from the 'rear' of the tube. That is the mass air flow sensor, and it looks like this if you take it out:
http://www.carpartswholesale.com/inc...dGFsbGF0aW9uLg==

They're about $150ish new.

You may also just need to clean it, and that's only $7 for a can of mass air cleaner, so I'd be tryin' that first.

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Given you've alread done the plugs, checked the coils, and have a newish throttle body, there's not much else than maybe the battery/alt isn't happy? And... then maybe... a pulley dragging or something...? Or a computer, which would suck a bit...

Hope that about the mass air helps, though, and it's what's ailin' ya so it's an easy fix!

 

Maybe the fuel pump? Most of the fuel pump problems were 05-06 but I have heard about some 07's having issues too.

 

Houtex...thank you for taking the time to respond to my message--and so thoroughly.
Yes, my engine is entirely stock.

Alternator was replaced in 2011 with EOM parts (dealership) so I'm hoping that's not the issue. I'll give the MAF sensor a peak when feeling brave--I'm not that mechanically inclined.

Hopefully, nothing serious. I'm a bit lucky in that I have a 100K mileage warranty through my insurance company which as come in handy lately. Although the deductible is a bit steep ($250)--it's saved my wallet on occasion.

The dealership was stumped as well---since it was impossible for them to duplicate the problem without driving the car all day. Also, it appears that its not throwing an codes and the engine check light does not come on.

If you have a suggestion on somewhere other than the dealership---I'm open to suggestions. My policy states that I can take my car anywhere...

05mustangsoa...I initially thought that as well..but checked out OK...or hasn't 'broken' severe enough for them to detect.

The plan is to purchase a '13 in the next two months, but I'm selling my car to a friend..and don't want to leave him hanging with this issue.

 

No problems, glad to try to help.

You don't need to be brave, just have a little common sense and the ability to turn a small rachet wrench or a screw driver. The MAF sensor just pops out with two screws/bolts, I just don't know which/how big. It bolts right back in. Only thing you could mess up, honestly, is the screw holes by over tightening, strippin' it out, being as it's plastic, and really, you can just not do that, right?

...maybe really bad gas that might've fouled up the injectors? Perhaps a little STP or Seafoam or something like that is in order, clean up the injectors a tad... but a clogged fuel filter, yeah, that could maybe do it.

Crud in the fuel tank too. Might could be fouling up the pickup, causing a starve...?

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Re: selling to a friend...

Only thing I can say is the last couple of times I did this... well, I hated to say "it worked for me, so..."

Thankfully, it did, right until I sold it. But it didn't stop them from questioning/blaming me about it.

All I'll say. It's your friend, just be prepared for teensy things to be blown up to zOMG proportions... because it'll happen, and it's just the way it is.

 

Sounds like coil or injector heat breakdown. I would start there

 

It sounds like some kind of heat soak ... I had a problem that was heat soak related and would only occur after driving on the interstate and then stopping at the market for 10 or 15 minutes. When I came out and started the car , my wide band a/f gauge would give an error and I at first thought was my O2 senor getting heat soak while I was in the store. The error the gauge was giving was for low voltage and after trying everything with the gauge and it's wiring , it turned out that the battery was going bad. After setting for a while the heat soak would drop it's power level enough that the gauge gave an error , that was the only indication that it was going bad ...