Dayton Daily News

Wheels: An e-mail from Alydia says, "I have a 1999 Oldsmobile Alero, and I am having a hard time finding out what is wrong with it. I had the catalytic converter and the resonator changed because the core of the converter was fried. After that, I noticed a loss in power and was told it was due to the constriction of air flow from the converter.

The problem now is when driving around 35 mph to 40 mph or different speeds, I notice my car loses power slightly, then picks back up. It's almost a feeling of running out of gas, except the car decelerates 2 or 3 miles then picks speed back up. All of this without me moving my foot on the gas pedal. I have had my car checked by certified transmission mechanics, and they say the transmission is in working order. Also, as the car loses power, the RPMs do not fluctuate as if it is the transmission. I say this because so many mechanics have asked me that question. I had my car checked by three different mechanics and each of them had a difficult time duplicating my complaint.

I know my car, and have even been insulted and told that it was the driver, not the car. I may be a woman, but I am not an idiot. There is also a foul odor that comes from the car. I had been told that was from bad fuel, but every time I fill up? Could this problem possibly be my O2 sensors? I know there are two of them. How can I find out which one, or if that is even the problem? I am desperate and I cannot find a mechanic that will treat me with the dignity and respect that I deserve. One gentleman did hook it up to a handheld computer device that read System Pass: No Fault Detected. Help me, please."

Halderman: I do believe you have an engine performance problem, because a catalytic converter does not fail by itself; it is hurt by a fault in the fuel and ignition system. The loss of power that feels like you are running out of gas could be exactly that — the fuel pump and/or fuel filter could be the cause.

These components can be tested, but if the fuel filter is original, I suggest that you have this replaced first and see if this one simple fix will take care of the power problem. However, a clogged fuel filter would not explain a converter failure, so that makes me think that there is a problem in the ignition system.

Have the system checked for output using a spark tester and have the technician check the spark plugs and coils for carbon tracks. The odor is likely caused by the ignition misfire loading the catalytic converter with unburned fuel. Fixing the ignition system will likely take care of your concerns.

James D. Halderman is an ASE-certified master technician, a member of the Society of Automotive Engineers and the author of 12 textbooks.

Submit your automotive care questions to Halderman via e-mail at jhalderman2@juno.com, or write him in care of: Wheels, Marketing Publications Department, Dayton Daily News, 1611 S. Main St., Dayton OH 45409.