Factory tune for VY S/C V6..

[Dylan]

Is the current tune standard?

[Jayme]

what is happening with it dropping into open loop is definitely lean cruise. but lean cruise is there from factory, so it cant be the root cause of the stalling!! im not saying turning it off wont stop it stalling, perhaps it will, who knows.... but factory cars dont stall, so lean cruise shouldnt matter!
the reason it drops in and out of lean cruise is because your engine temp drops out of the lean cruise enable temp, then once its back in closed loop, it heats up by another degree and goes above the enable temp again, and drops back into lean cruise. if your thermostat was an 89 degree like factory, it would just stay in lean cruise...

at the point it stalls in your log, it has dropped out of lean cruise and is pushing more fuel back into the engine. it still has reference pulses as we have RPM trace. unlikely to be spark related as you have replaced that. (unless it is wiring related) first thing I recommend is putting a fuel pressure guage onto it, and drive with the guage tucked under your wiper. see if the fuel pressure drops away when the problem occurrs.

[Dylan]

A new standard thermostat would be the price of postage for another memcal burnt probably.
Sounds like a good idea.

[immortality]

Thermostat is a PITA to replace, would be easier to change memcal. The1 probably has a spare memcal he could sell/burn for you.

Good to see others have come to a similar conclusion

[Dylan]

What state you in? Im in Vic could burn one if you wanted got one here.

[lowandslow]

Thanks Jayme, immortality and Dylan for your help.

Just strange as the thermostat has been in for well over 18 months and has been through all seasons, cold and hot without issue until the last couple of months. Very common thing to do on the L67.
I had a fuel pump put in it yesterday and the mechanic (Yeah...not doing a tank on my own on the ground again ha!) said the filter sock was dirty and there was some scum in the tank. Done the filter aswell. Perhaps age had wearied the pump combined with the dirty strainer it was just enough for it to stall out after a while.
I've done one log with the new pump since along the same stretch of road and it drops in and out of lean cruise many times without issue.

Dylan - If you could help me out mate it would be appreciated. Like you say, swapping a memcal is way easier than dealing with the thermostat on one of these things! I'll try and PM you.

Cheers!

[Jayme]

just to get us back on the same page, the thermostat is unrelated to the stalling issue. the thermostat causes it to drop in and out of lean cruise, which is not the reason it stalls. you said the new fuel pump was put in yesterday... perhaps that fixed the issue? all you can do is drive it and see.

[Dylan]

Your call mate I can do one. But as Jayme has reminded us. Id hate for you to pay for this and still have it stall on you.

[vs ss]

Exactly the only problem the thermostat is going to cause is slightly more engine wear due to running as low as 78 degrees.

[immortality]

I really can't see the thermostat causing increased engine wear, oil viscosity @ 180° F will be almost identical at 195° F. Both these temps are well within normal working limits of the oil. Engine wear occurs at cold starts. The higher engine running temps are used because it helps with tuning for emissions.