2nd Gear Poster
Join Date: May 2011
Location: Atlanta, Georgia
P0171 and P0172 at the same time?
I have an issue that i hope someone can provide some input on. For the past month my 95 tbird has been having lean codes for both banks. I would clear the codes and they would reaper after 200 miles or so. One day the CEL came back on and about two minutes later the fuel pump failed. I replaced the stock pump with a 190 lph pump along with a new fuel pressure regulator and new filter. Shortly after the CEL came back on only this time I had a Bank 2 lean and a Bank one rich. I swapped the upstream o2 sensors with each other to see if the problem would follow and it did. Noting this, I replaced both upstream o2 sensors with bosch replacements and I changed the spark plugs as well to motorcreft copper. All seemed well until a little after 200 miles the CEL came back on again, only this time it had codes for bank 1 lean and rich (P0171 and P0172).
I feel like this is just a computer issue as there is no way that one bank could lean and rich at the same time. I'm just not sure if the computer is sophisticated enough to track engine going back and forth between two contradicting conditions and spit out both codes.
I have contacted my tuner and he has stated that could be a bad ground, frayed o2 sensor wiring or possibly the pcm. I would like to know if there are any other possibilities to consider.
The car still has the stock injectors on it. The coil packs are fairly new and the wires are ford racing with about 15000 miles on them.
Also the car runs great. I don't have any complaints in the performance department.
Please let me know what you all think.
1995 Tbird 4.6 sohc