Official Thread for posting daily FE updates

[DRW]

Thanks for the tips on finding combined MPG rating! I just assumed the combined rating was halfway between city and highway. I just re-adjusted it in my garage, and now my rating looks even better.

[zpiloto]

Not so great a tank for me this time around. 30.5 . This included the smog testing and I also flushed the transmission with synthetic. I think that the amount of fuel this engine uses on start must be significant. My worst tanks are those that include alot of starts. It seems that if I am to sit for longer than 1-1.5 minutes it might be good to shut the engine off other wise it uses more fuel than to leave it running. But then again with FE feed back it just a guess. The next tank will have fresh transmission fluid and 1/4 wheel skirts so we'll see how that turns out.

[krousdb]

I couldn't help myself……. Last night Psy PM'd me about a Wai for the Prius. I told him that I had plans for one but I wanted to gather baseline data first. When I got up in the morning and checked the forecast, I saw that winds would be calm this morning and throughout the day. Not knowing when I would get another wind free day, I decided to spend 5 minutes to install the Wai tube and duct tape the grille openings. Compared to yesterday, the ave temps were 6F lower. Other than that, the drive was the same. The good news is that the Wai tube and grille block made a huge difference in IAT. The bad news is that my FE dropped from 57.3 to 56.7. My take on that is that either the 6F lower temps had a greater detrimental effect than any improvement gained by warmer IAT and ECT. Or, it could be that the Prius doesn't like the warmer air?

Yesterday, the ECT held steady at 185F and the IAT stayed, on average, 1F over ambient. Today, the ECT cycled between 198 and 204F, while the IAT cycled between 51 and 57F, or about 24F over ambient on average. The surprising thing was that the ECT and IAT cycling was out of phase. When ECT was high, IAT was low and vice versa. So when ECT was 204F, IAT was 51F. When ECT was 198F, IAT was 57F. It seems that the cycling could have been caused by the thermoostat opening and closing, which was not happening yesterday. I guess the thermostat never opened yesterday without the grille block. Another thing that I noticed was that the timing advance range shifted from 14 - 18 degrees to 12 to 16 degrees.

This afternoon the temps should be the same or slightly higher than yesterday's commute home. I'm hoping for better results.

[MetroMPG]

Originally Posted by krousdb

Another thing that I noticed was that the timing advance range shifted from 14 - 18 degrees to 12 to 16 degrees.

That's interesting. Could be part of the reason for not seeing a gain from the higher temps.

[diamondlarry]

I have heard that Saturn's are bad about FE drops at higher temps. I think the threshold is around 200F for ECT and IAT. Even though my IAT sensor mod "shows" 200+ it seems that when the actual temp rises over 200 is when the trouble starts. Timing is significantly reduced. The same thing seems to be true with respect to ECT. I have never encountered extended periods of temps over the 200 range so I can't comment personally on my car.

[zpiloto]

With Casper the IAT did not start retarding the timing until around 125 -130. I wouldn't think that the IAT of 57F wouldn't cause that. I thought that some one on here stated that once the Water temp get above a certain temp it changes the fuel map for more fuel for cooling purposes. Leave the WAI and remove the grill block and see it the timing changes and FE increases.

[diamondlarry]

With temps in the upper 40's and low 50's the last couple days, I have been averaging just over 51 mpg. Today I travelled 53.x miles and the SG was showing 51.x mpg. Yesterday I travelled 52.x miles and the FE reported was similar. The last time I filled the tank, the SG reported 46.2 and the calculated was 47.8.

[krousdb]

62.2 MPG on the drive home with 58F ambient temperature. The IAT bounced between 89 and 98F with the grille block and WAI. This tank is currently at 60.2 MPG, 310 miles.

[krousdb]

Temps have moderated here and the morning drive was at 44F, dry and calm. The IAT peaked at 80F and I had my best results yet for the morning drive, 60.2 MPG. Current tank, 378 miles at 60.2 MPG.

[diamondlarry]

For the morning part of my trip I averaged 46.9 and for the afternoon portion I got 54.4. I made a trip to the heart of the downtown of our neighboring city again and the SG was reporting 60.0 when I pulled into my spot. Once again the temps were over the magic 40F level. I just returned from my mom's and managed to get a 69.9.