Questions and Answers

Plymouth Acclaim Power Loss Issues Q. Dear Vince: I greatly appreciate all the help/advise you have provided to me on my 1993 Plymouth Acclaim. You know the entire history on loss of power issue with my 1993 Plymouth Acclaim, 4 cylinder, 86,000 miles, automatic transmission, P/S, and A/C. We have had theory at one point that the fuel pump might be going bad. This is the most of my worry. So I like to ask your advice.

The summary of history on this car is that we used to experience loss of power while driving at speeds. That got corrected after combination of timing belt job, use of frequent dry gas, fuel injector cleaner and changing Gas station from Gulf to Exxon and Hess. This was end of December 2003. Then, in February once I noticed hesitation when increasing speed, getting in to flow of traffic from an exit ramp, and then after once climbing a hill. Since almost last three months, I have neither experience loss of power nor hesitation. Except, the car broke camshaft a month ago. So my questions are;

1. Isn't it so that if I have a Fuel Pump that is going bad, the frequency of loss of power/hesitation would increase or I would hear noise from the Fuel Pump?
2. I still have code 21 for Oxygen Sensor. I have not replaced the O2 sensor yet as I am not 100% sure that it is bad.

The average is same as the car was new (26 City/29 Highway). Wouldn't the mpg suffer if I have bad O2 sensor? I would greatly appreciate you advise. Particularly on the Fuel Pump. It has been eight months since we experience the loss of power. So I would like to think that if the fuel pump is going bad, the situation would have got worst over time. But again, you would be the best adviser.

I look forward to hear form you.
Best Regards,
Naren

A. I think before we do anything else, we have to do something with the Oxygen Sensor (O2). It's difficult to perform a troubleshooting procedure on a foundation of bad components. The O2 sensor is easy enough to test, so lets do that first.

CAUTION: Use a high impedance [1] Digital Volt Ohm Meter (DVOM) ONLY, when testing components on computerized vehicles.

1. Make sure the vehicle is at normal operating temperature. Run the engine at 2,500 rpm for 3 minutes with the transmission in PARK (A/T) or NEUTRAL (M/T).

CAUTION: To avoid damaging sensor, voltmeter must be set in Volts mode only, (not ohms).

2. With engine OFF, connect the negative lead of the DVOM to engine ground. Set the DVOM to read DC VOLTS. Disconnect the oxygen sensor (O2S) electrical connector and connect the positive lead of the DVOM to the oxygen sensor signal wire, black/dark green.
3. Start engine. Create a lean condition, disconnect a vacuum line for 10 seconds. Voltage should decrease to 0.2 volt or less and remain there.
4. Create a rich condition, shoot some carburetor cleaner into the throttle body, for 10 seconds. Voltage should increase to 0.8 volt or more and remain there.
5. If sensor fails to vary according to the test steps above, the sensor is defective.
6. Connect sensor and clear codes.

Depending on the type of driving you do, you may or may not notice a drop in fuel economy. But you may notice a change in engine performance.