Originally Posted by
NomakeWan
If you are unsure of the condition of the engine components, the first thing you should be doing is replacing the O2 sensor. If this engine is still using the old TBI unheated one-wire O2 sensor, those are really not that great and don't last nearly as long as the heated O2 sensors that were introduced along with the sequential-injection LT1 in '94. So if you don't know if they've been replaced and you're unaware of their condition, just replace them. No sense chasing your tail looking at INT and BLM if the O2 sensor is not reacting accurately.
As for fuel, just hook a pressure gauge up to the port on the rail and watch it under load. I'm not intimately familiar with TBI engines so I can't tell you what the proper base fuel pressure is for a 454 TBI. If you know the correct value, then a pressure gauge is an easy and cheap way to confirm. Plus you can check to make sure it's actually able to hold pressure while you're at it. Again, no sense chasing your tail over bad readings if the underlying problem is something mechanical and not the tune.
If there's no IAT sensor, I'd wonder why that data is in the datastream. Hopefully it's just a bad datastream definition. If the ECM is actually trying to make corrections based on an IAT that doesn't exist, obviously that could be a problem. But again, I don't know enough about your engine to say.
Good luck!
As for BLMs, you should be looking for 124~132. Preferably 128 or lower. If you start seeing things going to 136 or higher, that's lean, so you'd be best to avoid that. But again, make sure your O2 sensor is actually good and your fuel pressure is solid before you try to mess around in the tune.
