Tuning for colder spark plugs? Cold Start/Idle?

[immortality]

So a few months ago I put colder spark plugs in our L67 Calais (3.2" pulley, large elbow, bigger TB, 5% OD balancer, 25mm blower spacer/insulator 82°C thermostat and MACE CAI modified for more cold air). The car has been running fine and it seems happier under boost with a little more timing in it.

Unfortunately 2 weeks ago it did foul the plugs. During the first week of the lockdown here in NZ I moved the car down to the bottom of our driveway, literally started the car, moved it 30 meters and shut it down. A week later I went to take the old girl for a spin and she didn't want to run, started and stalled twice and running very poorly, finally got it started and had to use plenty of throttle to keep it running whilst in was missing a couple of cylinders. Warmed her up a bit and took her out for a spin and it was running good on all cylinders. On subsequent days the missus took her out without issue. Ignition system is compromised of new Gorst coils, Autolite 605 spark plugs and Bosch LPG style leads that aren't too old.

Tuning changes I have made to date include leaning out open loop idle a touch to help clean the plugs once she is up to operating temp but this has not prevented the plug fouling issue as happened when the car was moved and did not get up to operating temp. I've also increased cold idle rpm a bit to help it warm up.

I'm considering reducing cold cranking pulse width a touch as sometimes it does smell a bit fuely straight after you start it.

I'd like to keep the colder plugs in the car as it's definitely better under boost but also need it to be reliable as a daily driver during colder weather once the lockdown in NZ ends and we can start motoring again.

Any thoughts, suggestions or experience using colder plugs would be greatly appreciated.

[delcowizzid]

Just go back to stock plugs we run them even at 400rwkw

[The1]

sounds like the classic DFI or Crank sensor starting to go.

[immortality]

Not really got any other symptoms. Just the dead cold start, otherwise it's happy as larry and drives fine. No weird stalling or other strange things happening.

[Charlescrown]

On cold startup all plugs are equal so I don't think that's your problem. If they fouled up when hot after driving then it may well be. How far from the std plugs did you go?

[immortality]

One heat range colder. Went from Autolite 606 to 605 plugs.

[immortality]

I do have a spare DFI module here so I might try swapping it out. Can't hurt.

[immortality]

Hmmm, these plugs came out today. This is after a drive around the block and quick cruise down the motorway.

[Charlescrown]

Looks a little lean. Looks like the colder plugs are a good choice.

[immortality]

I leaned out the open loop idle once up to temp to make sure the plugs stayed clean. Might drop it back down a touch as it's not fouling when it's at operating temp.

Had the exhaust manifold off as well today and the exhaust valves are also white so definitely not having issues with carbon...