I have been helping my father with his '94 to no avail.
He purchased an aftermarket exhaust that eliminated a cat and had a local mechanic and friend of the family install it. He had two new Toyota O2 sensors installed with it.
After installation, it immediately started throwing O2 sensor codes (27 I think?). We did a resistance check on the sensors and they seemed to be fine. We swapped in the old ones and the codes persisted.
I cleared the codes and the truck ran at ran fine for half a tank. CEL returned but the codes then included a 71 for EGR.
I cleaned up the connectors to the O2 sensors and cleared the codes again. The O2 codes disappeared for a short time, but the returned with completely new codes 25 and 28 for a lean mixture. It never stops!
And to throw another variable into the mix, my father had a piece of wood wedged between the wiring harness and the EGR pipe to insulate it against the heat. He removed it around this time and there is visible damage to the wrap around the harness near the EGR tube.
We're kind of at our wits end here. Our mechanic friend thinks it is possible he fouled the O2 sensors with penetrating oil during installation, so I was thinking about ordering some Densos just to try it out. If that didn't work, I was going to cut the wrap off the harness near the EGR to inspect the wires.
Advice? We could really use some direction here as we are a bit stumped.
He purchased an aftermarket exhaust that eliminated a cat and had a local mechanic and friend of the family install it. He had two new Toyota O2 sensors installed with it.
After installation, it immediately started throwing O2 sensor codes (27 I think?). We did a resistance check on the sensors and they seemed to be fine. We swapped in the old ones and the codes persisted.
I cleared the codes and the truck ran at ran fine for half a tank. CEL returned but the codes then included a 71 for EGR.
I cleaned up the connectors to the O2 sensors and cleared the codes again. The O2 codes disappeared for a short time, but the returned with completely new codes 25 and 28 for a lean mixture. It never stops!
And to throw another variable into the mix, my father had a piece of wood wedged between the wiring harness and the EGR pipe to insulate it against the heat. He removed it around this time and there is visible damage to the wrap around the harness near the EGR tube.
We're kind of at our wits end here. Our mechanic friend thinks it is possible he fouled the O2 sensors with penetrating oil during installation, so I was thinking about ordering some Densos just to try it out. If that didn't work, I was going to cut the wrap off the harness near the EGR to inspect the wires.
Advice? We could really use some direction here as we are a bit stumped.
