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Scangauge appears to be as it was, 1.8L engine, etc. Driving to work today, I got my normal MPG for at night. I was able to get my car to do the same actions I saw yesterday, but couldn't keep the speed. For at night my TPS reads 18 and sometimes dips to 17. If I let off just a tad bit, say where 17.5 should be, the IGN reading goes from 37/39 down to 24 and mpg instantly jumps to 52-55! So what I'm thinking is that the ECU thinks I'm coasting and it leans the AF mixure and retards the timing. Theory of mine is that there was a slight wind pushing me (north) and since I was running the gas peddel low enough, it was kind of doing a lean burn setup even though this car does not have that function (same engine in other cars can). When I perform more aero mods on the car, I should see this "lean burn" more often if my theory is correct.
While in the "lean burn" thing yesterday, I did notice the engine was a lot smoother than normal and sounded like it was under less load. When my car is fully warmed up, it idles around 675-700rpm and is very smooth running, just before peak temp, it runs 850-900 rpm and vibrates quite a lot. When it is idled to 700 and I give it gas to get the rpm to around 900, it vibrates as well. I think this is just the nature of this engine, but maybe it could be timing or fuel quality (E10+)? My engine spects say 9.5:1 compression, so maybe I should run 89 or 91 gas instead of 87?
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