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Hey guys this is my first post here. Hope everything is going well for everybody.

Here's my problem... My mother's 2001 Impala is lugging at low RPM when in 4th gear and I cannot for the life of me figure out why. It's been doing this for quite awhile. The car has a 3.4 with 142K miles on it. I replaced the plugs and wires at about 137K.

The problem is very noticeable under light acceleration around 45-60 mph. Once up to highway speeds, the lugging isn't as as bad but is still sometimes present, especially when going uphill. If you punch the gas and make the transmission downshift (or downshift into 3rd manually) the shaking goes away. Also, if you put the car into 3rd at around 30-35 the car will lug as well.

I really have no clue what to do. No CEL. I've done most of the cheap stuff - new air and fuel filters, injection cleaner, PCV valve. 20,000 miles since last transmission flush. On a side note, the sending unit for the fuel tank is a little flaky, especially when below a half tank. It's probably a long shot, but I'm wondering if this can be related to a fuel pump issue?

Any and all advice is appreciated! Please help me make this headache go away :)
 

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Do yourself a favor and have someone check to see if there are codes in the system. They might not set off a check engine light. Also what kind of plugs did you put in your car? A/C Delco plugs are the only ones that run right in these cars.
 

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Yeah I put in AC Delco's last fall. I replaced the originals with Bosch plugs at 100K, but they weren't holding up. I actually got a CEL which came back as a misfire on number 5, which is what prompted me to put in the Delco's. That went away with the new plugs, but the lugging did not.

Anyway, I'll take it down to Autozone and see what they say.
 

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2001 impala misfires under low rpm

Hey guys this is my first post here. Hope everything is going well for everybody.

Here's my problem... My mother's 2001 Impala is lugging at low RPM when in 4th gear and I cannot for the life of me figure out why. It's been doing this for quite awhile. The car has a 3.4 with 142K miles on it. I replaced the plugs and wires at about 137K.

The problem is very noticeable under light acceleration around 45-60 mph. Once up to highway speeds, the lugging isn't as as bad but is still sometimes present, especially when going uphill. If you punch the gas and make the transmission downshift (or downshift into 3rd manually) the shaking goes away. Also, if you put the car into 3rd at around 30-35 the car will lug as well.

I really have no clue what to do. No CEL. I've done most of the cheap stuff - new air and fuel filters, injection cleaner, PCV valve. 20,000 miles since last transmission flush. On a side note, the sending unit for the fuel tank is a little flaky, especially when below a half tank. It's probably a long shot, but I'm wondering if this can be related to a fuel pump issue?

Any and all advice is appreciated! Please help me make this headache go away :)
Hey, this is also my first post.
I am having the same problem with my 2001 Impala, except it's a 3.8L.
My Impala misfires at low RPM (under 3000) and only under Load.

I was reading a misfire on cylinder 3.
Changed the spark plugs and wires - no change.

Replaced 5 injectors with used ones (I only had 5) - Misfire on cylinder 6.
Switched the injectors around 6 with 4 - no change Misfire on cyl 6.

Changed fuel filter. Checked Fuel pressure - It's OK.
Switched the coils around - no change.

Disconnected all sensors one after the other - no change even with engine operating on only one sensor connected (map or maf).

The only difference I noticed is that my fuel economy improved after all these changes.

When I connect my obdII tester I notice that both fuel trims go all the way up to 16 or even 20 when the misfires happen for a long time.
Otherwise the fuel trims are usually between -3 and +3.


Did you end up fixing your problem. Please let me know I am out of ideas.
 
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