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HDGENE, Ford Senior Master/Diesel/Trans
Category: Ford
Satisfied Customers: 5647
Experience:  25 years Auto experience, Ford ,GM, Chrysler, Asian & European
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No one can fiugur out why my 2004 freestar hesitats. its

Customer Question

no one can fiugur out why my 2004 freestar hesitats. its only got 100000 miles. it will only hesitat under acceleration after its completly warm (15 miles driving) other than that there is no rhym or reason. some days it runs great all day. so far i took out very clogged fuel filter. which led to testing fuel pressure ( slightly sub-par) so changed pump. then i changed pcv then the pcv hose. had check engin light for mass air flow senser so i did that. there is only one thing i havent done and that the voltage light indicates alternator indicats alternator is sub-par but still charging (12.9 v instead of 13.9). i wont change it till the hesitation is gone. could this actually be causing extra electrical noise interfering with the pcm?
Submitted: 1 year ago.
Category: Ford
Expert:  HDGENE replied 1 year ago.

That is possible if the altenaotr is dropping out, no codes? If you disconnect the egr valve vacuum suply and plug it off does it still hesistate? At what speed is the hesisiation, take off from a stop or highway speeds? Feel like you are driving over a washboard road?

Customer: replied 1 year ago.
I only got code for low volts but still charging. if the alternator was cutting in and out the car would just run off battery. it was just at 55 mph but now it does under acceleration. sometimes its very slight and u think u hit a small bump but its actually the engine shaking from cutting in and out. but no not a washboard road but inbetween big hesitaitions are small ones that u can just feel the car shake a little. unless of course its in a good mood and runs great that day.
Expert:  HDGENE replied 1 year ago.

Ok yes it will run off the battery until it depletes the battery reserve power so need to adress any charging system concern first. Try unpluggint the egr valve and see if the concern continues. Certain model year applications had egr runner ports in the intake manifold if the egr valve is mounted to the side of the lower intake manifold. These ports would clog up and cause random misfire concerns when the egr valve is commanded on. So removing the egr vacuum supply would disable the valve operation to test if this is an issue

Customer: replied 1 year ago.
i disablesd erg vaccum and pluged up suction hose. ran same. studderded even harder. if you dont let go of gas peddle it surges on off real hard if u let off n throttle again u can work around it and keep it sublte. so yes the charging concern must be addressed as i have ordered alternator. i feel as if i should order the ignition coil pack as well or can we test this before i buy it?
Expert:  HDGENE replied 1 year ago.

Hello, coils are a common failure but they wont let you put it on before buying it, I have seen a lot of issues using aftermarket coils so I would recommend sending the money on a ford coil which will come with a 2 year unlimited mile warranty if it fails again own the road

Expert:  HDGENE replied 1 year ago.

How did you make out?

Expert:  HDGENE replied 1 year ago.

Hello, do you need more help with this concern?

Customer: replied 1 year ago.
was waiting on parts in the mail. got them installed. hesitation still persits. the alternator got replace along with coil pack and battery light is now off. how do i test the mapp sensor? I do have a code for evap system. looks like gas tank pressure sensor. from what i read this code and the evap system in general will not make your car run bad. true?
Expert:  HDGENE replied 1 year ago.

Hello, your vehicle doesnt use a MAP sensor it uses a mass air flow sensor which you replaced. The altenator could cause radio interference yes. Do you still have the hesitation? what code do you have for the evap system

Customer: replied 1 year ago.
I dont have the actual code number (sheet auto zone printed out) but anyway the code itself traslates to voltage out of parameters in the gas tank pressure sensor . Ofcoaurse they wanna sell me a gas tank sensor which is fine if i can fuiger this bigger problem out first since there is no evap situation that can cause this level of hesitation (when it happens). Which never has shown up in a code. I been clearing codes this whole time with the appropiate parts and new ones pop up like air flow sense voltage so i replaced part n cleared that code till this next one came up and none of these normal maintenece items (im at 10000 miles) have made any impact on the unpredictiable hesitaion. I even got a flashing engine light ( misfiring events) while the car would barly even run then check engine light quite flashing and car started runing alot better. So this was recently also as i also replaced the coil pack. Its odd so maney codes n parts needed all at once (inside few months). Sometimes i really gotta wonder about that pcm. do i got a crazy computer? weird enough to run the car good enough most days? sumetimes runs like a champ till its warmed up good and starts falling on its face. i back off and feather the throttle till i recover the engine (usually quickly).or the throttle position plate- sensor is worn- messed up? whats another good test ?
Expert:  HDGENE replied 1 year ago.

Yes you may have a water issue in the pcm connector as shown in this tsb attachment which kinda goes along the lines of your concern