Studdering under load/acceleration (not fuel filter)

kirkyg

Founding Member

Jun 14, 2002

3,568

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Beaumont, TX

May 11, 2008

#1

• May 11, 2008

• #1

I recently noticed my car studdering under acceleration especially when putting it in higher gears (4th, 5th) and pressing the pedal down a good bit at lower rpms. After reading around about this I came to the conclusion it was most likely just a clogged fuel filter so I changed that this weekend. I took it out for a spin and still at lower rpm's and it studders under load.

What's the next step to diagnosing? Any ideas on what else might be wrong. Honestly, I have a baby on the way and want to get the car tuned up and sell it so I need to get the little things resolved quickly.

I don't see any check engine lights and no other signs of problems. Could it be a bad coil pack? Thanks for any help in advance.

Kirk

 

the98stang

Active Member

Aug 12, 2005

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47

Clovis, CA

May 12, 2008

#2

• May 12, 2008

• #2

kirkyg said:

I recently noticed my car studdering under acceleration especially when putting it in higher gears (4th, 5th) and pressing the pedal down a good bit at lower rpms. After reading around about this I came to the conclusion it was most likely just a clogged fuel filter so I changed that this weekend. I took it out for a spin and still at lower rpm's and it studders under load.

What's the next step to diagnosing? Any ideas on what else might be wrong. Honestly, I have a baby on the way and want to get the car tuned up and sell it so I need to get the little things resolved quickly.

I don't see any check engine lights and no other signs of problems. Could it be a bad coil pack? Thanks for any help in advance.

Kirk

Click to expand...

Pull each COP one at a time and see if any of the cylinders are causing the problem. If it's not the spark plugs it could be a vacuum leak.

 

B

blubullett

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Jun 22, 2006

535

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18

Modesto, CA

May 12, 2008

#3

• May 12, 2008

• #3

How old are your spark plugs? Maybeits time for some new ones.

 

CTGrey02

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May 22, 2002

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Bristol, CT

May 12, 2008

#4

• May 12, 2008

• #4

Start pulling the plugs Kirk. See what they all look like. After that start checking the coils as stated above. Sounds like a miss-fire more so than a fuel problem. Unless the cars underwater I think you got enough air.

 

kirkyg

Founding Member

Jun 14, 2002

3,568

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Beaumont, TX

May 13, 2008

#5

• May 13, 2008

• #5

Well, the car has 81k miles on it and the spark plugs have never been changed. I guess ill be doing that this weekend. Should I just stay with the stock platinum plugs or go with another set?? What is stock spark plug gap for a 2002 gt (I haven't looked that up yet)?

Also, if it was a COP how would I know when pulling them off there was a problem. With plugs atleast I can see they are worn on the tips or have deposit on them...

Thanks,

Kirk

 

astronut1885

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Jan 31, 2002

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Assonet, MA

May 13, 2008

#6

• May 13, 2008

• #6

Sounds like tune up time to me. New plugs, some seafoam, a little Lucas fuel treatment, and some new oil, and you should no longer have a problem. 81k on stock plugs....I wonder what those electrodes look like.

 

W

wohorsy2002

New Member

Apr 2, 2008

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May 13, 2008

#7

• May 13, 2008

• #7

like someone said above... pull each coil pack one at a time and see which one doesnt change the way the car runs.... now you know the cylinder. pull the pack and check for any moisture. Then pull plug and check for it to be soaked in gas which will not allow for it to fire. If so try replacing the plugs. If this does not work then get a stethoscope and listen to injector and make sure it is pulsing.

Hope this helps good luck

 

kirkyg

Founding Member

Jun 14, 2002

3,568

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Beaumont, TX

May 13, 2008

#8

• May 13, 2008

• #8

It would be hard to see a change in how the motor is running with this problem because it only occurs while driving under load at lower rpms. I'm going to change the plugs this weekend. Let me know if there are any tricks with changing them on the stang

 

astronut1885

Founding Member

Jan 31, 2002

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Assonet, MA

May 13, 2008

#9

• May 13, 2008

• #9

Go slow, torque to 13 ftlbs, take your time. If you goof it up, the motor can spit a plug and you'll have a whole world of problems.

 

kirkyg

Founding Member

Jun 14, 2002

3,568

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56

Beaumont, TX

May 31, 2008

#10

• May 31, 2008

• #10

So i replaced my spark plugs looked over everything carefully. I believe that the PCV is ok but I did not pull it out because I believe 2001 models you have to unbolt the valve cover which is a little too intense for me to take on right now.

I did notice after alot of looking over the engine that on the drivers side there is a hose that goes into the top of that valve cover. The grommet or seal around it looks like it has let some oil residue out and one of the spark plugs on that side of the engine had a little oil residue as well.

What is this part and how easy is it to replace? Could this be my problem?

Kirk

 

Hardtop68

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Aug 23, 1999

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Wherever they need me

Jun 8, 2008

#11

• Jun 8, 2008

• #11

I had the same problem... it started only at high RPMs... I checked the spark plugs, all OK... I checked the impedance on all coils, all OK...

Last week it started to happen at low RPM's as well but only when my gas tank was below 3/4 full...

I replaced the fuel pump... the suction strainer was plugged. I could had changed the strainer only but I replaced the whole fuel pump instead because of the mileage (131,000 miles.)

Fuel pump replacement is an afternoon job.

Cheers, Ric.

 

kirkyg

Founding Member

Jun 14, 2002

3,568

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56

Beaumont, TX

Jun 9, 2008

#12

• Jun 9, 2008

• #12

Hardtop68 said:

I had the same problem... it started only at high RPMs... I checked the spark plugs, all OK... I checked the impedance on all coils, all OK...

Last week it started to happen at low RPM's as well but only when my gas tank was below 3/4 full...

I replaced the fuel pump... the suction strainer was plugged. I could had changed the strainer only but I replaced the whole fuel pump instead because of the mileage (131,000 miles.)

Fuel pump replacement is an afternoon job.

Cheers, Ric.

Click to expand...

I was able to resolve my problem. I paid 65 bucks to have my car hooked up to ODBII to tell me whats wrong though

one of my ignition coil's were bad. 66.99 on top of that Ouch.

Oh well, it beats the hell out of having a leaking pile of an engine which is always a possibility at higher miles.

Kirk