Setup:
L8 ECU with MSD closed loop chip for 55’s
071’s motorcraft gapped 0,6mm
GrpA coil

I am running this setup and it all runs very fine. Start a the first hit when cold, no misfires off or on boost and drives lovely. Only minor thing is when engine is hot and running in closed loop mode the idle revs go up and down for a little bit. Say from 900rpm up to 1000 rpm and back. Not very much but I like to have it steady.

I wounder if someone with this same setup has had the same issue and managed to solve it with a little tweak or something. For instance with a different plugs or gap, altering the basic idle rpm?

 

Can happen some times as they fo run lean at idle do can pick up on the lambda surge.

You can give the global mod a tweek to richer it a tad this can cure it, also make sure the base idle is correct with the iscv unplugged as this can also cause issues.

If all else fails then just fire the chip in with your invoice and I can add a little fuel in at idle to steady it up for you