4.6L (1996-2004 Modular) Mustang Technical discussions on 1996-2004 4.6 Liter Modular Motors (2V and 4V) within.

Car Stutters Under Load

Old 03-21-2012, 02:36 PM
  #1  
hpwrestler220
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Default Car Stutters Under Load

Was in the car the other day with some friends and the car ran great. Drove all over the place and then came home. On the way home the car just randomly started sputtering when I would hit the gas. It does it all the time under any load and only during acceleration. Car revs fine in neutral.

Fuel Pump was replaced 4 months ago.
Spark plugs and Coils were replaced 2 years ago

For some reason I have a feeling that it's a bad fuel pump AGAIN...

Any thoughts?
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Old 03-21-2012, 02:43 PM
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Derf00
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Check your fuel pressure, Check the plugs for any cracks.

Hook up a scanner to the OBDII port so you can see what the engine is doing under load when it sputters. If you're fuel trim goes way up, that could be a symptom of low fuel pressure and the injectors staying open longer to get the required fuel into the cylinder. Timing going all wonky would be a cracked plug since or spark leak.
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Old 03-21-2012, 04:03 PM
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cliffyk
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What sort of plugs, how many miles on them?
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Old 03-21-2012, 04:08 PM
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EddyG
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Originally Posted by hpwrestler220
Was in the car the other day with some friends and the car ran great. Drove all over the place and then came home. On the way home the car just randomly started sputtering when I would hit the gas. It does it all the time under any load and only during acceleration. Car revs fine in neutral.

Fuel Pump was replaced 4 months ago.
Spark plugs and Coils were replaced 2 years ago

For some reason I have a feeling that it's a bad fuel pump AGAIN...

Any thoughts?
Change your spark plug wires.
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Old 03-21-2012, 04:21 PM
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cliffyk
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Originally Posted by EddyG
Change your spark plug wires.
It's a new-edge, no plug wires--COPs...
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Old 03-21-2012, 05:43 PM
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hpwrestler220
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Okay guys I just went to my mechanic. My Tuner wasn't throwing any codes so we used the $10,000 snap-on scanner instead LOL. Cylinders 5 & 6 were misfiring. I changed the COP's and it's all good now! Hopefully it stays that way because i ended up buying all new COP's a while back when I ruined my stock ones washing my engine bay. I re-used two of the OEM ones and it runs fine now so i'm guessing the stock ones i just put back in must not have fried from the engine wash 2 years ago.

Plugs are stock motorcraft replacements
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Old 03-21-2012, 08:01 PM
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Originally Posted by cliffyk
It's a new-edge, no plug wires--COPs...
Oh whoops didn't realize that it was a new edge.
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