Problems after a tune-up. Need help.

[GT Fanatic]

So, if I drive the 2000 expedition for 1/2 an hour, it will start to sputter. More at higher speeds and seems to be on inclines. Previous computer diagnostic said there was a misfire in 3. Replaced coil pack in 3 and it's still doing it. Can a brand new spark plug be defective? It is some cheap ass auto zone shit. I'm going to go have codes checked again tomorrow. I like to figure this out before Friday, so my sister can drive it to Texas for Christmas.

TIA for any and all help.

It doesn't sputter unless driven for a while. Nothing will happen in 15 minutes. About how long it takers her to drive to work.

[JordanFiveOh]

Maybe your porcelain's cracked. Pull the plug.

[Greenster95]

bad Intake manifold gasket or vacum leak can make it misefire.

[CRASH]

Did it do the same thing before AND after the coil pack was swapped ?

Did you change ANYTHING else, other than the #3 coil pack ? Spark plug ?

Did you replace the plug only on #3 cylinder ? If so, did you gap it to factory specs ?

How many miles are on this vehicle ?

-Aaron

[GT Fanatic]

Did you change ANYTHING else, other than the #3 coil pack ? Nope Spark plug ? Nope

Did you replace the plug only on #3 cylinder ? If so, did you gap it to factory specs ? Yes, if I recall it was .54

How many miles are on this vehicle ?129k I believe.

The first cylinder on the drivers side closest to the radiator we got a new fuel injector for.

Fixing to go to Autozone to check for codes.

[CRASH]

Did you change ANYTHING else, other than the #3 coil pack ? Nope Spark plug ? Nope

Did you replace the plug only on #3 cylinder ? If so, did you gap it to factory specs ? Yes, if I recall it was .54

How many miles are on this vehicle ?129k I believe.

The first cylinder on the drivers side closest to the radiator we got a new fuel injector for.

Fixing to go to Autozone to check for codes.

You lost me there. So you DID change one plug ? You also said you've got a new fuel injector for one cylinder....has it been installed yet ?

Do you know if all of the plugs and wires/coil packs have ever been changed on this vehicle yet ?

-Aaron

[GT Fanatic]

You lost me there. So you DID change one plug ? You also said you've got a new fuel injector for one cylinder....has it been installed yet ?

Do you know if all of the plugs and wires/coil packs have ever been changed on this vehicle yet ?

-Aaron

Sorry, I changed all the spark plugs and gapped them. I got a new fuel injector cause the boot/seal/fitting at the bottom of the old one cracked and no one sold replacement boots. I did install it as well.

Since the sputtering started I have no replaced the new plug I installed.

[majorownage]

Isn't .54 a bit wide?

[90GT50]

Isn't .54 a bit wide?

.054, hopefully. But, even then.

[majorownage]

.054, hopefully. But, even then.

Exactly.

[krazy kris]

should be somewhere between .052 to .056