Chrysler Repair: 1990 Labaron bad gas mileage, sensor calibration, oxygen sensor

Question
Hi ROLAND, I have a 1990 Labaron with a 3 litre v-6 motor  that I bought 2 months ago. It ran great when I bought it. Now my idle is down to about 750 from 1000 and I'm getting bad gas mileage about 12-14 miles per gallon. I also smell gas when I start it and by the exhaust. I changed plugs, wires cap, rotor, and all air filter and it did not get any better. I did the on /off steps with the engine light twice and came up with this code 1 -PAUSE 2- PAUSE 5- PAUSE 1- PAUSE 5- PAUSE- 5 PAUSE thanks for any help that you can give me


Answer
Hi Marvin,
The 12 (battery disconnected some time in the recent past) and 55 (end of readout) are not unexpected and would not be involved in your situation. The 51 code says the oxygen sensor thinks the mixture is lean (which is contrary to your observation). The most likely cause is an oxygen sensor that is not functioning properly, though it could be an intake manifold leak or low fuel pressure or some other sensor calibration that is involved. But if the oxygen sensor was telling the wrong tale, the compensation would be an attempt by the engine controller to lengthen the fuel injection pulses and thus the smell of fuel you are detecting. So my inclination would be to replace the oxygen sensor if you don't notice any vacuum hoses disconnected from the intake manifold. Check the wires at the sensor which is located on the rear cylinder bank exhaust manifold. Use some penetrating fluid on the threads and let it sit before trying to remove it. And be very careful to not damage the wires where they enter the sensor when you install the new one.
Roland