Quote:
Originally Posted by jfitzpat
I'm not sure that I like this suggestion. The big problems in winter efficiency are fuel blends, road conditions, and dense intake air.
That last one is killer for a couple of reasons, first, denser air means more fuel required to reach stoichiometric ratio, and the vehicle needs to burn at stoich to get the exhaust temps nec. for the cat to operate for emissions. Second, as any small plane pilot can tell you, peak performance soars, so you are throttling back more for the same performance. Throttling back creates vacuum, which means you are operating less efficiently.
A warmer engine can offset this a bit, but the efficiency change is not that great. The much bigger impact is rather or not the ECU has decided you are warm enough to run closed loop. If you are driving open loop in winter, the vehicle is generally pig rich, wasting fuel, and operating with less efficient emissions control.
This is why we are so focussed on more durable sensors and faster wideband measurement. So vehicles can get closed loop faster, and stay closed loop under greater loads.
From all the measurements I've seen, it would be better to make your driving decision based on rather or not the ECU is reporting closed loop operation yet, not a fixed temperature in, say, engine coolant. The problem with the later is that it will generally result in some needless idling, and, because of the extra fuel needed to achieve stoich, idling is more costly (efficiency wise) in winter.
-jjf
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I appreciate what you are saying, and agree with you, in this and your other posts today. But, my intent was not to suggest that we should wait till the coolant is warm before driving, just that we should use whatever means available to get the engine/drivetrain up to temp. and use the SG to monitor it. this thread was about what guages to use in winter. Most new cars with heated O2 sensors will drop into closed loop very quickly, long before the engine is warm, so the Cl Lp guage doesn't seem of much value to me. I never warm up anyway, just start and go and drive gently. A warm air intake is the only way I know of to help offset the effect of denser winter air and they are difficult to implement effectively and come with thier own set of complications. I have used the intake air temp guage in the past to evaluate the effectiveness of a WAI but I see no other use for it otherwise. I know from my SG that cold intake air hurts FE, as does a cold engine, drivetrain, and bad roads. I live in "the great white north" afterall.
Thanks for your comments about oil. I too am a strong believer in synthetic oil.