car runs great with the holly tbi but in the morning when cold runs really rich and did not do that with the stock tbi anyone know what caused this and how to fix. thanks guys 89 rs 305 tbi

what injectors and what FP? i will guess holley are 55 lbs rated for 20 lbs FP. what does exhaust look like on cold start? are you logging ALDL? you need to do that pronto.

exhaust black at start up 55lb injectors and dont know what aldl is...thanks in advance

DIAGNOSTIC LINK. allows you to read the sensors and especially the 02 sensor. check the stickies on DIY Prom. might need to consider the fuel pressure.

I went thru the same thing when I put one on my 88 Blazer. If you hook up ALDL to your vehicle, you will find out that it's also running about 20% rich in closed loop too. From experience, I can tell you that the only cure is chip tuning. It's not that hard, it's just tedious and time consuming. Do a search on my username or on "Holley 670 TBI" and you'll find out more than you ever wanted to know.