I've read on many posts here where replacing the stock injectors with the 24b SVO injectors wouldn't cause a problem since the PCM should easily adjust to the slight increase. I installed a new set a short time ago and immediately after doing so, I continually throw P0171 & P0174 codes indicating a lean condition. If anything, I thought the engine would run slightly RICHer.

The engine runs VERY smoothly, and when I rev the engine to redline, I get noticeable black smoke which indicates a rich mixture (right?). The codes stay on for about 3 days, goes off for one day, then repeats itself. Any suggestions? Will I have to reprogram the PCM on my '97 LT1?

I have new Denso O2 sensors installed (replaced the Bosch I had earlier since I heard they weren't very good).

 

Sounds like you may have huge vacuum leaks..... did you make sure you got all the old o-rings out with the stock injectors, and then used good o-rings on the new injectors? Make sure you didn't cut the o-rings when you installed the injectors?

Denso is a Japanese licensee for many Bosch products.... so you probably have essentially the same sensors you had before. Why didn't you use the AC/Delco sensors?

 

I did replace all the injector o-rings. Never thought about vacuum leaks, I'll recheck the injector seatings to make sure they are all properly aligned.
I was asking around for good "performance" products and many recommended the SVO injectors over the AC Delco's. One quote was, "funny that one of the best parts for an LT1 is a Ford product!" It is ironic. LOL Oh, they were a lot cheaper than the AC Delco's from the sources I checked on line so I thought I had a win-win situation.

 

All of your major tuners will tell you to use the A/C delco O2 sensors because they are much easier to tune. I bet with using a aftermarket O2 it is causing you to throw your codes.
HVY SS