2001 Chevy Impala Hesitation under medium to heavy throttle

Tiny
CAVERMAN
  • MEMBER
  • 2001 CHEVROLET IMPALA
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 96,000 MILES
My Impala recently started sputtering/hesitating (like no fuel or spark) under medium to heavy throttle. If I drive with slow to medium - easy throttle around town I have no problems. About 9 mths ago I changed the spark plugs, wires, new intake gasket, fuel filter, and catalytic converter. I'm not getting any kind of check engine light when this happens.

Some suggestions are:
-catalytic converter (recently changed - shouldn't be it)
-fuel regulator
-fuel pump
-EGR (I think that was what was suggested)

So I put a fuel pressure guage on the fuel regulator and started the car. It immediately jumps to about 60psi and then starts to settle down to 44 - 46 psi (I read somewhere that it should be 46psi). The guage had a slight leak so after I turned off the engine I lost all pressure pretty quick but that could've just been the guage.

No one seems to know what it is and all of the above suggestions aren't cheap. Regulator ($90), Pump ($330).

Any ideas on what it could be or how I can narrow the issue down?
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Tuesday, May 12th, 2009 AT 11:27 PM

7 Replies

Tiny
RHALL77
  • MEMBER
Try disconnecting your mass air flow sensor and test driving it. This may help. Also you can try disconnecting your cat converter and see if you hae power. Do you know how much fuel volume you have. If the the pressure is fine and your volume is low it can also cause this.
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Wednesday, May 13th, 2009 AT 9:53 AM
Tiny
CAVERMAN
  • MEMBER
I'll see about the Mass Air Flow sensor. The Cat was just replaced about 9 mths ago so I don't think (at least hope not) that's the issue.

I'm thinking about just replacing the Fuel Pump because I heard that they are only good for about 100k (I have 96k) and it seems like alot of people have issues with that.
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Wednesday, May 13th, 2009 AT 10:06 AM
Tiny
RHALL77
  • MEMBER
The fuel pump is common. Try the maf sensor first
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Wednesday, May 13th, 2009 AT 10:41 AM
Tiny
CAVERMAN
  • MEMBER
My wife is still out in the car right now so I'll have to try the MAF tonight if I can but won't it not run if it's not hooked up?

Since the FP is a common problem and will probably go out soon since I have 96K I think I going to change that no matter what.
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Wednesday, May 13th, 2009 AT 3:42 PM
Tiny
RHALL77
  • MEMBER
The PCM will basically go into default mode and it will still run. Try it and let me know what happends.
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Wednesday, May 13th, 2009 AT 3:51 PM
Tiny
CAVERMAN
  • MEMBER
Since I'm limited in my mechnic knowledge, is there a plug on the MAF that I can just unplug? Isnt the MAF the large sensor where air come into the intake?
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Wednesday, May 13th, 2009 AT 3:54 PM
Tiny
RHALL77
  • MEMBER
Yes you are correct on both ends. Let me know what you find
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+1
Wednesday, May 13th, 2009 AT 4:03 PM

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