Acceleration Question

"02" 3400, I have not been able to get a clear answer on this so here goes:
when cruising from 40 to 60 when going to accelerate it seems very slow response unless I press 1/2 inch or more on pedal. I have never had an engine respond like this before and am wondering if this normal for these 3400's. Frustrates me to no end. I can think of nothing that would cause this lest it be something in the programming of throttle response. Could it be a bad throttle position sensor? Have new plugs/wires, no misses and runs great otherwise. All thoughts appreciated...dave:banghead:

Never driven the impala so I can't say for sure. But, lots of times when I hear about poor throttle response it ends up being a bad Cat. Hopefully, this is not your problem.

could be a lot, i am thinking it might be a fuel filter or your catalytic converter starting to clog. You can buy an inexpensive pressure tester that screws in in place of the ox sensor. The filter is not too difficult to replace and there is no schedule to replace the filter published by GM. GM just says to replace when clogged. How many miles do you have,?

Didn't think about the fuel filter. If it was time for you to change the plugs/wires, I would bet it needs changing too. I'd prolly go that route first.

Read through the "2003 Impala won't run right" post here...

I would not mind reading that myself, where is it ?

I would not mind reading that myself, where is it ?

Like 3 topics below this one:screwy:

http://www.automotiveforums.com/vbulletin/showthread.php?t=573844

Here some info from ALLDATA maybe this would help, good luck.

Restricted Exhaust

Restricted Exhaust

Diagnostic Aids
For dual exhaust systems a quick check of exhaust flow will help determine which side of the exhaust system is restricted. The side that has less exhaust flow is the side that will be suspect, and the diagnosis should begin there.

Test Description
The numbers below refer to the step numbers on the diagnostic table.


The exhaust system has very low back pressure under normal conditions. If the exhaust system is restricted, a significant increase in the exhaust pressure is noticed on the J 35314-A Exhaust Back Pressure Gage. Removing the H02S sensor may set a DTC. When finishing this diagnostic table, be sure to clear all codes.
This step will isolate the catalytic converter (http://www.alldatadiy.com/alldata/AFI~V6770573~C37398~R0~OD~N/0/89012112/94694975/94694986/94694990/34853741/100411974/34856670/56492525) from the remainder of the exhaust system.
Confirming that the condition has been fixed is essential. If the symptom still exists and the vehicle has a dual exhaust system, proceed to Step 2 and repeat the diagnostic procedure on the opposite exhaust pipe (http://www.alldatadiy.com/alldata/AFI~V6770573~C37398~R0~OD~N/0/89012112/94694975/94694986/94694990/34853741/100411974/34856670/34856803). Steps 1 - 4http://www.alldatadiy.com/alldata/AFI~V6770573~C37398~R0~OB0~P4R0H~N/0/89012112/94694975/94694986/94694990/34853741/100411974/34856670/34856990/106949511/106954443/119099561/119099562
Steps 5 - 8http://www.alldatadiy.com/alldata/AFI~V6770573~C37398~R0~OB0~P4R0H~N/0/89012112/94694975/94694986/94694990/34853741/100411974/34856670/34856990/106949511/106954443/119099561/105644506

Hey, thanks all for the responses...63.3k, I have also read thru the thread suggested previous of my posting. As for the fuel filter, I can almost get my mind around that except for what seems to be normal performance other than the speed zone mentioned. As for the Cat, I have yet to get that checked due to cost if it is not found defective. Disabled vet with limited funds so I was looking for what other possible causes it could be. I have not had good experiences with dealer service departments through the years. I understand carburated systems pretty well, but the electronic/TB systems I have yet to figure out. Things like the TPS, MAF, etc. are still a bit confusing to me, how they work or what goes wrong with them. So what the heck, maybe this is just normal for these Impalas, I havn't driven any others to compare. But my 92 3.1 Lumina didn't respond like this, acceleration was immediate all through the range. I'll ponder the suggestions above a bit more before I head to the dealer. Thanks again for your thoughts....dave

you can buy a back pressure tester on the internet for under $70, take out the ox sensor and screw inplace... i think the guage measures up to 8 lbs.

OK, thanks for the info on the back pressure gage availability. the chevy dealer service for check is 80+ tax, title and ins. I think I'll go that route instead of diy. Just have to wait till I have the funds to do so. In the meantime I'll search for better understanding of how the TB/ injection systems work.