2002 GT - Jumpy 25-40 mph

[infidex]

I have a 2002 GT w/ auto trans. Lately the car has been jumpy, or I guess you could say it has the shudders while driving it 25-40mph, after you get over 40 it runs smooth. It has 78k on it, only mods are K&N filter and Borla Catbacks that were put on around 30k. I have changed the spark plugs around 60k, with the triple prong platinums, should I go back to factory type plugs? The car has always shifted into OD at low speeds like 30, so I always turn OD off, so I know it's not that. Any ideas? Going to replace spark plugs today figuring if one is fouled that may tell me I have a bad coil.

 

[ProCharger GT]

When did you first start noticing it being "jumpy"?

 

[ATRKalMt]

Might consider droping the trans pan and taking a peak. 30 mph is a little soon for overdrive to come on and the torque load at that speed is incredible. Possibly pulled through the "OD" clutches or cooked them along with the directs. At least pull the dipstick and smell the fluid. Also use a white paper towel to make the first wipe of the stick. Look to see that there is no black left on it. That indicates clutch,rubber,aluminum,iron particulates suspended in fluid to small for the filter to catch. Hope this is not the case however and good luck.

 

[twogts4us]

changed your fuel filter lately?

 

[infidex]

Changed fuel filter about 5 months ago, so that didn't help. I pulled the triple prong platinum plugs I put in at 60k, and put the factory motorcraft plugs in, and it runs tons better. I notice a tiny bit of jumpiness from time to time, but the problem is 98% of the time not there.

I know my battery is on its last legs, my needles sweep when I start my car, so I'm going to pick up a new one tonight, hoping to keep my car for another 5 years with no major problems, I only drive 5k a year these days.

 

[04YELLOWGT]

I was going to reccomend to look at your plugs because I had the same problem in my car except it was a 60-65 MPH and it would jerk. I looked at my plugs and three of them were toast so I put all new TR6s in and the car ran like a champ.

 

[BlackGT4.6]

you also may try cleaning your maf sensor. the oil from the k&n filter can cause all kinds of things. try using a little rubbing alchoal on it.

 

[SVT32VDOHC]

First of all....all of those triple and waud plugs are junk!!! They foul quickly. Nothing but problems in my dirt bikes, and many of my friends cars that believe their marketing crap!!!! I would change them back to Motorcraft and gap them at the recommended specs.

Next, if it is not the plugs.....it could be the trans. I had a 95 stang that ****tered, and I had a bad overdrive spring. The trans shop fixed it for 50 bucks. That helped alot. They also informed me my converter was not locking up and that caused the trans to run about 15-20* hotter....but I didn't fix that...I just added a trans cooler. It later got worse and shuttered again...I swapped converters and I had a smooth trans.

 

[infidex]

Got a new battery, runs a lot better. I know my old battery was causing the computer to reset every day, the gages would sweep, radio would be on AM station like it lost connection to the battery. So basically the trans and eng had to relearn the fuel/air mix and driving patterns over, so that probably contributed to the poor running/shuttering I was getting. I only drive 3 miles to work, so it never gets to relearn properly. I put the new battery in last night, went for a 20 mile drive, and it ran like a champ on the way to work this morning.

 

[BlackenedSVT]

Hopes its not a stator problem in the transmission.

How often do you change your auto trans fluid? At 78k miles on the car, you should have done it at LEAST once already