missfiring/stumbling on a 3.8L mustang

crm318

New Member
Nov 27, 2006
2
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San Marcos, TX
recently my 2002 mustang with a 3.8L has been missfiring/stumbling. it occurs when i am accelerating around 1700-2000 rpms at the end of a gear. the car will jerk a few times before it shifts. the car only has 35k miles on it. i was thinking of a spark plug change but it only has 35k on it. could i go to autozone for a diagnostic? what do you guys think?
 
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Definately do a diagnostic to pull any codes firing. Also check your fuel filter, spark plugs, wires, oil, transmission fluids, and it wouldn't hurt to sea foam your car too. Just did mine and it runs GREAT now.

Doc
 
...and it wouldn't hurt to sea foam your car too. Just did mine and it runs GREAT now.

How does one do that? I'm afraid my '99 (with 130,000 miles on it) needs a re-build (the people who had it before me didn't take too good of care of it).

I'm considering getting a re-built short block assembly (since I'll only have two days at my friend's garage to do it), and cleaning my intake, heads, etc, and throwing them on the newer block before installing the engine (though I'm not entirely convinced this is necessary). How can I determine if the engine needs such a re-build, and if not, what should I do? The engine stumbles, the fuel economy is shot to Hell.....
 
My car is doing the exact same thing. I'm just waiting for it to blow so I'll finally have the motivation to rebuild the engine with a 2 cylinder upgrade; and I'm too cheap to take it to the dealer for a code read since I can't find any other place that reads odb ii ;). I'm not sure what the problem is, but I think it could be a bad coil pack. During idle, I can hear the engine missing. And it has plugs and wires that are maybe 6 months old.

As doc said, definitely check your trans fluid level. If its too high or too low, it'll shift weird.
 
I'm not sure what the problem is, but I think it could be a bad coil pack. During idle, I can hear the engine missing. And it has plugs and wires that are maybe 6 months old.

This is exactly what I was thinking. I had my #1 coil go bad on my '01 at around 70K miles.

AutoZone can't pull codes from the 1994-95 mustangs. Only 96+.

Or so I've been told.

Your ODB II is identical to '96+ V6 Mustangs. There should be no reason for them not to be able to pull the code.

Hell, they can even read ODB I codes. You just have to find a guy that knows what he's doing.
When I took my '95 in, the first guy I asked said they couldn't, but he wasn't even wearing a uniform(still in training I guess). I asked him if he was sure, and he asked another employee who also said they couldn't. So I then asked one of the managers and he grabbed the ODBI reader and helped me.

I think they just train their people to say, "No" to anyone with a pre-'96 car, without even asking what kind of car it is. The manager that helped me actually asked what kind of car I had and he knew he could pull ODBI from a '95 Mustang GT. The same guy probably would've known the '95 V6 Mustang would have ODB II.