You can attach another wideband as input, but it won't be used for closed loop calculations. Only for data logging.

 

Im having the same exact issue you described. Im also running 12554271 injectors. Any chance you can share a gcf / or let me know what changes i should be making to mine?

 

I just did a term x swap on a 5.3 in a C3 vette. 60lb deka injectors bc I had them left over which are really 70-72lb at 58 psi. I opted for the internal map and had it hooked up and Started the car up and the fueling was 10:1 and I couldn’t figureit out for a sec. shut it down and went through the tune again and found nothing. Went over the connections and that’s when I found I didn’t connect the vacuum hose to the intake when I pulled it after getting it all setup to check something. Plugged it on the intake nipple and boom AFRs back to 14:1. PCM thought the car was at WOT seeing 95kpa even tho TPS and rpm were at 0 and idle.

Sounds exactly like what you have going on. Make sure the correct map is selected and that the plastic nippled they give u in a bag are actually open and will flow vacuum. What is your map reading at idle? And are you sure you have the correct map selected? Even if the injectors are off a good bit the stock fuel correction is like 50% which is a lot.

 

In my experience, that handheld is garbage for doing the tune. If you want to use it to monitor gauges, great. Now I will say, I'm not new to tuning, but I am certainly no expert. I want to see everything about the tune, BEFORE I even start it. I'll look over it 2 or 3 evenings just to be sure. I'm older than I was, so call it missing more, or just wanting to be sure. I use my tablet for datalogs, and that's way easier to xfer what I want to base, save and go again.
You say the fuel pressure is set to 60 using a Corvette regulator. Have you verified that at the rail? It will compensate, but it works out better if your checking the info your telling it, is accurate.

 

If you haven’t pick up some low dollar motor sports 100psi sensors and they are plug and play for the Holley term x and are only like $35-37 each. I run them and verified oil and fuel pressure on both my setups. My corvette regulator C3 runs a -6AN PTFE single rail feed (deadhead) and turns out fuel pressure is actually 60psi (wix filter/reg) when I thought it was suppose to be 58psi. I adjusted the injector data to match that new flow rate after first start.

 

I really wonder why Holley does it this way other than lower costs. They should offer adding a second sensor to the other bank as a option. I bet most people would shell out the extra money for that. I know I would.

 

I did the exact same thing on my car with Low Dollar Motorsports sensors. They are really good quality and worth noting that they offer free shipping on those sensors. I've ordered 3 so far.

 

Same! I have 3 of them as well. I should have went with 4 but I opted for the stock oil pressure sensor on one of my motors which I think only reads to 60psi. Quality and feel on them seems really good and never had an issue with them. I like that they come with the plugs and pins so you can wire up your own harness or add them to a system like the term X for something extra. Free FAST shipping too!