BS3 Cranking Table & IAC

[DukeGN]

I've been tinkering with the cranking table and IAC to get the car to start without a lot of cranking. The car has 96 lb injectors and is a 274 cu in Stage II motor. Could someone share with me their experience for the cranking table for initial setup (around 77 degrees or more) as well as fully warmed up (196)? How about IAC start position -- should it be around 111 for 77.9 degrees and 65 for 169? Right now it cranks for a while and fires after I open the throttle. I'm thinking too much fuel but not sure how low to go.

Any help is appreciated.

 

[norbs]

What is your cranking PW ? are you running a distributor or DIS?

 

[DukeGN]

Stock ignition system (maybe COP next year). Fully warmed up it's 4.5 ms and 8 ms for 77.9F. The base tune was 8.8 ms and 17.6 ms for 77.9. I keep taking it down, just don't know how far to go. Base tune (from different GN tuned by BWR) had smaller injectors and motor wasn't as big. I'm thinking of taking it to 2 ms and 5 ms tomorrow to see what happens. I know what the motor does when it's too much -- cranks until I open the throttle to let air in, but I'm less sure what happens when it's too low.

 

[norbs]

I wouldn't take it below about 4 ms hot. The thing is the injectors wont fire until the cam sync pulse happens, so sometimes it will take longer to start depending where the engine shut off. If its too low it will just take longer to start I would think, or multiple attempts. If the IAC start postion is too high the motor will flare to 2000 rpm when cranking, keep lowering it until it stops flaring maybe about 1300 rpm is ok.

 

[norbs]

Glad you posted your outcome.

 

[DukeGN]

I tried 4 ms without being warmed up and it cranked for a long time. So I'm thinking that's not enough. Drove it to the gas station, not fully warmed up but close, and it cranked on 2ms and it fired about the same as 3.5 ms. So on the warmer scale, I'm thinking of keeping it low. Once I actually get it tuned as it should be, I will definitely follow up. At this rate, could be next year because I only drive it about once a month.

 

[norbs]

Thanks for the update. YOu may want to log ther cam sync to see when it sparks and then log the cranking time after the cam sync to see if there is a change after altering your settings.

 

[DukeGN]

Okay, I will try to figure that out. Thanks for all of your help -- I'll post back with more later.