Stutter while driving

[coffee_hound]

I have an 04 EB Expy with a 5.4. While driving i get an occasional bump or stutter, it doesn't happen while accelerating, or while idling. only while driving at a steady speed on flat ground. if i give it more gas it stops, i replaced the spark plugs (Motorcraft platinum) checked the coils with an ohm meter, changed the oil & filter, trans filter, fuel filter & cleaned the throttle body. It's as if it is trying to down shift from OD but then doesn't.Has anyone seen this? any ideas?

CH

 

[JUST4FUN]

if you turn off the od does it still do it. mabey the coverter is locking and unlocking. take it to a trans shop an ask them to pull the trans codes

 

[coffee_hound]

Is that the same as reading the codes from the plug under the dash?, the check engine light isn't coming on.

 

[JUST4FUN]

yes BUT the trans will not set the light, trans codes are stored in the puter. i think you need the trans software to read

 

[coffee_hound]

Oh, ok. I went to the auto parts store (AutoZone), they read codes for free, they said it was clear. will a normal code reader read what you're talking about? I'll ask them if they have one that will read trans codes.

 

[coffee_hound]

I haven't found a place to read my transmission codes yet, i did try driving around with the od off and it still does it, i listened carefully and tried pushing the gas while holding the brake and got a weird vibration. I went back home and started looking at my coil packs. I started at #1 and went up the line with my ohm meter. #1 .8 ohms, #2 .9 ohms, #3 .8 ohms, #4 1.4 ohms. I took #4 out and measured it again and it went down to .7 ohms. I tapped it with a screwdriver handle and it changed each time. i went and bought a new one and now so far all is well in the jungle.

 

[mustangswan]

Most of the time it is a coil that is going bad(changing the plugs will not fix it, but if you replace the coil, replace the plug). The best way to find out is to get in to the MODE 6 data, of the OBD II data and find what cylinder is misfiring. This is what keeps track of misfires to turn on the Check Engine light. It takes a really good scan tool to access this info. Also the trans codes are stored in the PCM, so if their was a trans code it would have come up when they scanned it. Hope this is helpful.