383 LT1 Camaro, XE236/242 cam, M6, Accel DFI gen 6.

I recently installed the DFI and have gotten the car relatively tuned in. Once the car is warmed up, the driveability is good and the car will idle okay. When I first start the car, it will not idle though. If I crack the throttle blades a little, it will idle fine on startup, but then starts to race once it warms up. It's like I have to choose whether I want it to idle cold or warm, but I an't get both. Any advice? Also, FYI, it is set up to run in open loop all the time, which seems to provide the best driveability.

Thanks!

 

I have no experience with the gen 6 dfi. But usually something like this either needs adjustment with the cold start enrichment, and a little bit of help with the target cold idle speed. When you crank the throttle open the idle air controller will be shut all the way when it finally warms up and doesnt need as much air.

Look at the iac step readings or % and make sure its in an acceptable range under both cases.

 

Agreed with ws6. Also, you might need to adjust the throttle blades open slightly and/or drill a small hole in the throttle blades (depending on the tb used) to allow for a slight amount of increase airflow at idle.

 

here's some info on TB adjustment.. http://www.ls1tech.com/forums/showthread.php?t=177230 ' I cranked mine open to .73 volts and it helped. But I have a mild CAM, IMO drilling may be needed but it should be your last resort. My IAC is now at 66 during 800 RPM idle. If you tune there are a few tables to look at. 'Closed TPS Spark Advance Vs RPM' You can crank up the idle timing a few degrees, ' IAC Target RPM Vs Coolant Temp Vs Gear " to set your idle speed , 'Idle overspeed Spark Retard', 'Idle Underspeed Spark Advance' to hold the idle speed. 'Spark Correction Vs MAP Vs Coolant Temp ' will retard spark when engine is cold and takes timing away from the Closed TPS Spark Advance setting. Some of the Coolant Temp settings switch around the 80*C (176*F) range if you have a 160* T-stat make sure any temp settings are the same for the 68*C (154*F) and 80*C setting otherwise you will be changing timing whenever you go above or below 176* during normal driving.

 

Thanks for the advice. The Accel setup is a little different than the stock PCM though. My TB is already drilled a little bit and I have also cracked the blades slightly. I slotted the TPS so that I could bring the TPS reading back down to .5%. The problem isn't that it won't idle...it will idle just fine with IAC counts around 30 I think, when it is warm. When it is cold, the IAC counts will start high but then they will keep dropping to the point it stalls itself out. I haven't been able to figure out why. Maybe I'll try messing with the timing and fuel some more.

When the car is cold/warming up, should it like more or less timing?

 

If it stalls out it is likely because your counts keep dropping your target idle rpm vs coolant temp is screwed up, and you're just able to stay running when warmed up and the blades open farther because its unable to cut off enough air to keep make it stall wherever its target idle rpm is set to.

Run it a little fat when its cold within reason.

If you could post like a screenshot of the software with all the available menus listed there I may be able to help after asking you to show me a few select others. All of this stuff pretty much operates the same way its just some have features others do not.