Missing at Idle with EDIS

[gmedlicott]

Has anyone else experienced missing at idle and rougher engine operation with EDIS? My engine runs OK but stumbles at idle (~750rpm), and gets worse as the inlet air temp goes up and idle drops. Ignition advance at idle is 16deg, though I’ve tried between 10-20deg, and A/F is ~14.1 (Innovate WB). So far I’ve only been able to get it running semi smooth by tuning to ~12.5:1 at idle, though no where near inline 6 smooth.

The engine is an ’86 BMW 3.5L inline 6 with 8:1 compression. Cranking compression is 175psi across the board. I’ve replaced the plugs and wires (plugs gapped to Ford EDIS specs of 0.035”), changed the injectors for a set of known good ones, changed the fuel filter, and cleaned the engine and chassis grounds. So far the biggest idle quality improvement has come by rewiring the EDIS coils with 12 gage wire, but the stumble is still there.

I have a V2.2 board with MS&S-EDIS. I previously ran MS on another engine, then converted it to run on EDIS and it ran rougher. I’ve switched the whole setup to the current engine with the same results.

Also, maybe unrelated but when I Key-on, the Megatune reads 8rpm without the engine cranking. I’ve run shielded wire for the VR and SAW signals, though the EDIS is currently mounted in a bad location with the engine wiring harness running right next to the coils.

Could interference be causing the stumble? Or a weak EDIS coil set? Anyone else had this problem and solved it? Any help would be greatly appreciated - I’ve been trying to track this down for quite some time now.

Thanks

Giles

[therealpinto]

I have done 3 MS installs with EDIS (2 V6's, 1 I4) and have helped map another one (I4) and none of them have had a problem getting the idle even, no stumbling or other problems.

The only problems we have had with regards to EDIS have been fouled plugs.

Can you verify if you have spark on all cylinders?

/Gustaf