My LSS has a new fuel pump, lines, filter, battery, more than frequent oil changes because of the heat down here, and the fuel pump isnt the problem.. check engine light is still not on,, it stalls, chugs and sputters.. whats wrong with her??

SOURCE: 99 olds alero 2.4

I'm sure you have installed a fuel pressure gauge and monitored the fuel pressure while the problem is occurring?Another diagnostic tool which is easy to do,is while the problem is occurring,unplug one sensor at a time beginning with the Mass Air Flow first,.if it uses one.Many times,not always,depending on the sensor,if the sensor is taken out of the picture as far as what the PCM is seeing,like unplugging the MAF,the PCM will substitute the missing sensor output with a generic value that will allow the engine to at least run,and if unplugging for example the MAF,the engine idle speed returns to normal,you know you're onto the problem.You didn't mention if the engine ran ok other than the idle problem.As far as checking for vacuum leaks,i use something like brake cleaner or WD 40,more of a liquid,and it does sound like a vacuum leak.Plastic intake manifolds do develop nearly invisible cracks that open up more with heat.Revsisit the possibility.And as for the PCM,it is possible,but more likely a mechanical problem.Lastly,remove an O2 sensor or two before the catalytic convertor,run the engine and see if anything changes.Cheap way to verify the catalytic convertor is flowing and not restricting engine airflow,as i have seen bad cats cause misfire codes and strange problems.Good luck.

Mike Butler

• 6674 Answers
• Posted on May 26, 2009

SOURCE: Car keeps stalling has all new parts

Run it into autozone or Pep Boys and get a free trouble code scan, and see what comes up, then we can go from there.

SOURCE: engines stall shortly after starting

Hi. the pump may be strained, due to a clog in the filter. I recommend replacing the fuel filter and pump in this case. i would also change the air filter as well.

If you have the time, go ahead and swap out the wires and plugs as well.

SOURCE: sluggish at take off

Try driving it with the mass air flow sensor unplugged and see how it acts

SOURCE: engine runs rough new fuel pump and filter new

requiresa a litte knowledge to analize the info the computer is giving you ? not being smartelec just these cars generally only had minor issues with this condition either the converter was clogged or the mass airflow meter failing both are easy find with proper scanner so you may want to spend the $50 to get it tested good luck