2002 Buick LeSabre 3800 P0131 code

I'm lost on this one. Problem has existed for about 4 months now. The car will hesitate from a stop, cold or hot. Slow to respond to the throttle inputs. Acts like it starving for fuel. There may have been an O2 sensor lean code, but I can't remember. If it was, it does not exist now. Here is what has been done so far:

Complete tune-up, fuel filter, both O2 sensors, entire exhaust system (was covered under GM 80K Emission warranty; the converter was clogged), injector service. New O2 sensors ran for about 2 weeks before new converter was installed.

Fuel pressure test checks 55 PSI KOEO, 46 to 48 KOER. Checked for vacuum leaks: none. Ignition Control Module check good.

Did have a battery problem about 3 weeks ago: sluggish start, when I checked the battery, it was shot. The positive terminal had rotted out as AC Delco factory batteries have been prone to do.

What I've narrowed it down to: Intake plenum; ECU (maybe damaged from voltage spike from battery problem); weak fuel pump;

Is there something I'm missing? This really has me stumped. Any help would be GREATLY appriciated.

Thank you,
Joe

Helo

The ECU must be ok, (the battery shouldn´t affected).
You told there are no vacuum leaks, but recheck.
Check all the intake system, could be an intake leak, leak in the plenum or leak in the intake manifold, leak near the injecotors.
Also, if your car is equipped with EGR valve, take out the valve and check its condition for proper operation, check where the EGR valve fits on and check if there is nothing clugged or dammaged in the passages, could be that the outside air is leaking down in an internal passage of the EGR and these could produce the erratic idle..

Keep posted

Thanks for the input...I will recheck the vacuum system and the EGR.

The problem does not exist at idle, only when the car is under acceleration (taking off from a start or accelerating for a pass).

I'll check the things you mentioned and post back with results, or lack thereof...

is the converter plugged again?

Thanks for the question, but its not possible...the problem still existed after it was replaced (as in within the first mile down the road). The dealership replaced everything from the manifolds back. I thought that was the problem when I had the flow test done, but was really disappointed when it did not solve the issue.

What I was thinking, and maybe I'm wrong, was that maybe the O2 sensors were damaged again in the couple of weeks between their replacement and the converter replacement. Does this sound viable?

Is that car equipped with a map or a MAF? what's it reading on a scan tool? What are the fuel trims doing? Is the fuel pressure bleeding off or correct? Some gms had real problems with plugging injectors as well the intake gaskets need to be verified, the egr port through the intake, clean throttle body etc, etc! you need to the 02 scoped to verify what it's really seeing!