Well it was 34 this morning. Two days ago I changed the ECT sensor with a new OEM item. I meant to hook up reader before I started to see if it read true temp but I accidentally started it and it ran good. Maybe sensor was a fix but I’d like to see it get into the 20s before I get a fuzzy feeling it’s fixed. I’ll keep updated.
35 ambient temp outside. Vehicle sat cold for 12 hours. My engine temp was 3 Celsius and my IAT was 8. That equates to about 45 F so there is defiantly a difference. Prior to changing the ECT sensor it was 9C at 35F outside. So the ECT did drop to being accuarate after I changed it.
Maybe it is my MAF sensor reading high and effecting timing while cold. Hate to spend $50 on a new one just to try it.
OK .... converting Silligrade to Fahrenheit .... so 9°Silligrade = 48.2°F, and 3°S = 37.4°F whatever ... so, yeah ... being off a bunch of degrees will definitely affect cold start ... and also running performance, but only up to a point.
It can cause either an enriched air:fuel mixture or one that is too lean... but only to preset operational parameters ... again: only up to the moment it goes Closed Loop.
The intake air temp helps in the simple computation to establish a "Look Up Value" affected by air density or ambient temperature and OBD2 Readiness parameters. There's more but I'll stop here.
Your problem appears ..... if my thermal calculations are even close to correct ... to be leanness... and that's a very unstable operating situation in cold temps.
After Closed Loop is established, things like the Oxygen Sensor(s) start getting chatty and the feedback sensors go Greenboard and the ECM takes over working on achieving the ultimate 13.7:1 ratio as a Golden Value. .
Air temperatures are important, but I am old school enough to believe that the O2 sensors become the master decider for operating the whole system, correlating all the incoming data to ultimately protect the cat.
If the cat fails, everything goes bad ---> emissions AND performance.
This makes total sense. Its basically seeing it warm outside and doesn't need to "choke" the engine for enriched fuel. Using your old school . Then I thinking once it runs for 5 sencong 3-5 times and dies the cylinders are warm enough for the lean fuel and it begins to run. It prob still lean but just enough to keep running. Guess I going to try the MAF. Thanks guys Ill keep yeah updates.
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