troubleshoot

hello everyone, pretty new here and looking for advice. so I've been chasing down this problem for quite some time, it all started when i swapped my oem catted down pipe back on for emissions from my catless dp also during that process I decided to clean the egr valve and throttle body. When I...

I took my MazdaSpeed3 to the emissions place and they said they couldn’t read the OBD port, so they couldn’t test it. I took it to a shop and they could read it fine, so I went to another emissions testing place but again, they couldn’t read it so they couldn’t test it. Anyone have any idea what...