I have two questions regarding fuel mixture.
1) Does the M180 engine tend to burn leaner in the winter than the summer? With cold air being more dense, it seems like the engine could burn more fuel and therefore leaner. This of course assumes that all adjustments remains equal from summer to winter.
The reason for asking is that my plugs are the cleanest I have ever seen them and I really haven't changed any settings since it was 100F outside. This is the first year that I have zeroed in on fuel mixture adjustments and things have remained unchanged from summer to winter. If the mixture will go back a little richer this summer, I don't want to change the overall mixture adjustment. Just wondering if this is a normal occurrence.
2) My M180 engine will run at lower rpms (700) and lean AFTER the WRD air valve closes at 160F (confirmed). However, when I drive the car for 5 more minutes (fully warm), the idle speed goes to 850 and the mixture is perfect and stays that way. It is only the time between the WRD closing and 5 minutes of driving that the engine runs lean and low rpm.
The cold running is normally rich at 900 rpm, then climbs to 1000 rpm and slightly rich as the engine warms up. The engine then slows down a bit to 850 while running slightly lean just BEFORE the WRD closes. Again,once the WRD does close, it runs leaner and slower until I drive it for awhile. What adjustment would I need to do to correct that lean running after the wrd closes but not affect the fully warmed mixture?