Hey guys I have an odd issue. Have a 302 out of a 91 mustang in a jeep YJ. We used a new Painless harness and a used A9L ECU. The issue I was having was it seems very Rich and doesn't like to idle. I pulled the codes and all it has is codes for the egr and canister purge which this swap has neither.
I checked voltage on the IAT, ECT, and TPS all look good. When I check the MAF it has the correct 12v and ground. The issue I find is the with the key on I have no ground at the signal return wire. It reads the same as the signal wire which reads battery voltage even when running. I assume this is why it is wanting to run rich. I've checked readings both at the sensor and at the ECU and they read the same. Is there a chance there is an issue in the ECU
I checked voltage on the IAT, ECT, and TPS all look good. When I check the MAF it has the correct 12v and ground. The issue I find is the with the key on I have no ground at the signal return wire. It reads the same as the signal wire which reads battery voltage even when running. I assume this is why it is wanting to run rich. I've checked readings both at the sensor and at the ECU and they read the same. Is there a chance there is an issue in the ECU