I have a 2005 Impala with 3.8L in it. The car has 130,000 miles on it. Runs great except on quick acceleration, it stumbles and hesitates, loses power and the check engine light flashes. The light will continue to flash for a little while after car is running at constant speed and then goes out. The light never stays lit, it only flashes. When I check for codes, none are ever set.

This went on for awhile. Finally one day a code was set. I forgot what the code was but it was for #3 misfire.

Sure enough I checked the plugs and found #3 was cracked so I replaced all the plugs. I also replaced the fuel filter.

The problem however still exists. Hard to moderate acceleration causes a stumble, low power and hesitation, engine light flashes for awhile, stops flashing and then goes out.


After reading several posts, it seems that I might have a catalytic converter starting to plug-up but none of the posts that I have read seem to state the same circumstances.

Any ideas???

 

How are you checking for codes?!

 

I have a code scanner I purchased from Sears a few years ago. It does both OBDI and OBDII. It's how I found that #3 cylinder had the misfire. I did not write down the code, that is why I don't remember what it was. It scanned the code and read #3 misfire. I pulled #3 plug and found it was cracked.

 

I would try changing the coil packs. I had the same problem with my cylinder #6, and after i changed it the problem stopped

 

the flashing mil means the engine is misfiring. this condition can damage the catalytic convertor. If you think the cat is clogged, remove the pre cat 02 sensor from the exhaust and test drive it...if the misfire is gone the cat is clogged.

for me though....get the codes read first and post them here. start diagnosing based on the code.