New to LS stuff and had a bit of an issue the other night with my LS swap third gen camaro. For reference, I've been daily driving this swap all summer and it's been running great. Even had it dyno'd last month (391 wheel). Got a FiTech 70069 with the 55lb injectors and I'm running it with a Terminator X. The other night I almost didn't make it home. I noticed it was surging like I was running out of gas but the fuel pressure was solid. The AFR on the other hand was going very lean every time it stumbled. To try and visualize what it felt like, at cruise or at acceleration imagine the low lines are normal 13-14ish afr and the high lines are 16-18ish: __----__-____-----___-_-___-------___----___--__----__. And, of course, you could feel the lack of power when it was spiking high afr.

I bought one of those stethoscopes the next day and when out to try and make it do it again and it wouldn't. Even drove it around the block a few times and it ran fine. I definitely wont trust it until I confirm wtf happened. Am I correct in that it sounds like an injector intermittently failing? How many bad injectors would it take to do what it was doing? Just 1?

 

Check your fuel filter.

 

Fitech fuel systems been failing alot here lately. I would look into another brand if i was you.

 

A miss blows unburned air into the exhaust no matter what causes it, so that automatically shows a dramatic lean spike. Start with the usual diagnostic suspects like burned or loose plug wires, loose or dirty grounds, etc.