Hesitation problem is back.

04GT · Aug 28, 2005

My problem with hesitation is back.

Problem is hesitation at WOT after driving 30+ miles it hot weather.

I thought I had fixed it a week or so ago. Replaced MAF and it seemed alot better. Today, it is pretty hot, like 90 degrees and it happened again. Not as bad as before though. Before, it would get so bad that I had to pull over. Then I would shut the engine off for a minute, start it back up, and it would run OK for awhile.

Temp gauge never shows it's overheating.

Before replacing the MAF, I replaced the plugs and one of the COPs trying to fix the same problem.

Anybody have any ideas about what else to check?

Is this something I'm just gonna have to live with?

Kilgore Trout · Aug 28, 2005

Hell no it is not something you are going to have to live with

How many miles are on the car? Did you replace the MAF with the stock part#?

04GT · Aug 28, 2005

Car has almost 39K on it. Replaced MAF with stock part#.

Check computer, too. No error codes reported.

Kilgore Trout · Aug 28, 2005

At that milage it is worth changing the fuel filter. I really think it is spark or fuel flow related. Have you checked your plug wells for liquid? If you silicone spray your rubber COP boots real good they will form a better seal and prevent liquid in the plug wells if it is there...

04GT · Aug 28, 2005

Fuel filter was changed @ 30K.

If it was the fuel filter, wouldn't it hesitate @ WOT all the time? Only does it when it's been drive 30+ miles at one time.

There was some kind of moisture or oil in some of the plug wells when I changed them.

Fat Tony · Aug 28, 2005

You might want to check out your TPS sensor, especially if you have a aftermarket throttle body. My buddies sensor went bad and he had a simular problem.

myponyrocks · Aug 28, 2005

maybe the MAF sensor moved a tad? Even a slight degreee can FUBAR the car.

forpit2000gt · Aug 28, 2005

now sounding more like the fuel pump. A mechanic with the right equipment can find this. They need to know the exact circumstance that makes it happen. The more detai;ed you can be the better.

04GT · Aug 29, 2005

Fat Tony said:
You might want to check out your TPS sensor, especially if you have a aftermarket throttle body. My buddies sensor went bad and he had a simular problem.

Can over-oiling your K&N foul out this sensor like it does the MAF?

If so, that may be it. This problem originally started after I did that, which was about 4 mos ago. I have since replaced the K&N with my CAI.

Looks like the TPS sensor is only about $35. Maybe I'll replace it and see it that's it. Certainly will cost less than taking it to Ford so they can tell me "can't recreate the problem"...again.

Kilgore Trout · Aug 29, 2005

The TPS is very difficult to remove because of thread lock. Make sure you have the right tools... Might want to do a search for tips on getting those screws out...

forpit2000gt · Aug 29, 2005

do you have the factory air tube and filter? if so, I would put it back to stock tyo start with. With the proper scan tool and information on when and how it happens, a mechanic can find the problem. Depending on the Ford dealer, they can find it as well.

04GT · Aug 29, 2005

I've been reading about the TPS. I'm gonna use my Predator to check some of the TPS parameters and see what it says. TP V parameter is supposed to show voltage and TP MODE is supposed to show partial throttle vs WOT.

hotdog71 · Aug 29, 2005

Hi All

I have a same problem with mine. I gave up taking to Ford I tried 2 different dealers and both found sweet FA, one did try changing the IAC which seemed to help a bit but the problem soon came back.
After I installed the Predator tune it is almost not noticable now two weeks on, so fingers crossed..

MGSTANG · Aug 29, 2005

Is it between 1000-2000 RPM. Car sorta feels like it's surging/bucking?

04GT · Aug 29, 2005

Logged some data with my Predator (which was kinda cool!). Drove the car about 40 miles before it started hesitating...or should I say misfiring according to this data. Got a really weird reading on the Trottle Position Sensor at misfire. 437V! Did they leave out a decimal point?! I was watch the TPS reading when I was driving and looked like it was only going as high as 4.63V. It stayed at .97V at idle.

Acronym Data Description
MFFRPM 4431RPM Engine RPM @ Time of Misfire
MFFLOAD 60.6% Engine Load @ Time of Misfire
MFFVS 23MPH Vehicle Speed @ Time of Misfire
MFFIAT 84F Intake Air Temp @ Time of Misfire
MFFSOAK 10MIN Engine-Off Soak Time @ Time of Misfire
MFFRNTM 247SEC Engine Running Time @ Time of Misfire
MFFTP 437V Throttle Position @ Time of Misfire
MFFTCNT 17# # of Drive Cycles @ Time of Misfire
02S12 0.77V TRACTION MTR TEMP
02S11 0.4V 02 SENS BANK 1 UPSTREAM
02S22 0.81V 02 SENS BANK 1 DNSTREAM
02S22SV 0.81V 02 SENS BANK 2 UPSTREAM
02S21 0.44V 02 SENS BANK 2 DNSTREAM
FRP 40psi FUEL RAIL PRES SENS
FRP V 2.78 FUEL RAIL PRES SENS-VOLT
FTP V 1.70V FUEL TANK PRES-VOLT
FTP 121.48H2O FUEL TANK PRES PURGE MONITOR
ECT 194F ENGINE COOLANT TEMP

Sorry if it's hard to read. Forum doesn't support HTML tables, I guess.

Any ideas after seeing data above?

04GT · Aug 29, 2005

MGSTANG said:
Is it between 1000-2000 RPM. Car sorta feels like it's surging/bucking?

Not really. It's at higher RPMs, more than 3K. Feels more like missing, but sometimes it does "buck".

timeless2 · Aug 29, 2005

Have you ruled out the IAC?

forpit2000gt · Aug 29, 2005

I stated earlier about the fuel pump. 40 psi is fine. what tune do you have in it. timing? I had surging/bucking when I had the timing to far advanced.Have you put the tune back to stock. If it does it with the stock tune, put the stock intake pipe and filter back on. get rid of the problem(fix it) then add a piece at a time untill you find the problem.

04GT · Aug 29, 2005

forpit2000gt said:
I stated earlier about the fuel pump. 40 psi is fine. what tune do you have in it. timing? I had surging/bucking when I had the timing to far advanced.Have you put the tune back to stock. If it does it with the stock tune, put the stock intake pipe and filter back on. get rid of the problem(fix it) then add a piece at a time untill you find the problem.

Tune is predator one. I think the timing is at 17. Haven't changed it. Kinda would hate to put the stock stuff back on. That Demolet intake is a PITA to install. Besides...the mods seemed to help the problem. It was worse with stock tune and 87 octane. But, that was before I replaced the MAF.

forpit2000gt · Aug 29, 2005

I had bucking at anything above 14 in the timing. Try taking out down to 12 or 13.
Mine went away with less timing.

Hesitation problem is back.

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