I've updated a 91 RS 305 with a Vortec 350 engine. I'm using a Vortec TBI intake. I have installed 350 injectors in the old 305 throttle body. I have programmed the PROM chip myself using the $61 definition file original to the 91 RS 305 / 1228746 ECM.

I am wondering what the TBI IAC steps should be at when the engine is warmed up. The data logs show 60 ~ 70 steps, is this correct?

Thanks
dave w

Normally I like to see 10-15 counts @ idle, 60-70 is definitely excessive.

Did you or prior move the throttle stop screw? If the throttle plates are closed excessively you need to have them at a minimum opening value. Seaqrch. If they are too closed engine will not get fuel at idle. That was my issue early this spring. I would leave the .bin coolant temp IAC values stock(for now) and open that TSS and watch IAC counts drop.

I had to remove the idle stop screw cover, so the thottle still had the factory settings. I was able to get the steps down to 15 ~ 20. When I got to 10 steps the idle was over 1400 RPM's. I have not changed the PROM idle settings. With 15~ 20 steps the idle is about 650 ~ 750 RPM. Not the expected results I was looking for, but I can live with 15 ~ 20 steps for now.

dave w