105 MPG coast

[CoyoteX]

I didn't really think it would work but it was worth a shot mentioning it That pesky O2 sensor just keeps taking all the fun out of goofy ideas.

On your car does the converter stay locked up when coasting in gear so it coasts with the injectors off like a manual trans car would do while coasting. If it does I wonder if coasting in D with the injectors off but not coasting as far before having to resume driving would be better than coasting a longer distance in N but using a small amount of gas idling the engine?

[Bill in Houston]

I'm suspicious that the scangauge recalibration might have been the biggest factor in the change you saw. Was the change in the right direction to explain your improvement?

That said, the grille block should help you coast a little faster, so there is some real improvement in there, most likely.

[savoF3]

Originally Posted by popimp

I'm trying. We're probably going to New Orleans this weekend. About 70 miles from Biloxi. What would be the most effecient speed on a 70 mph I-10?

45mph ... probably unbearable though.

Find out! Take it out on a flat road, warm up and plot a speed<->mpg curve like I did when we were talking about it way back. I found a sizeable difference because of the aero just between 45 and 50. If you find that grill block flattens your curve out past 45 a ways I'd love to know.

[cfg83]

Coyote X -

Originally Posted by Coyote X

I didn't really think it would work but it was worth a shot mentioning it That pesky O2 sensor just keeps taking all the fun out of goofy ideas.

On your car does the converter stay locked up when coasting in gear so it coasts with the injectors off like a manual trans car would do while coasting. If it does I wonder if coasting in D with the injectors off but not coasting as far before having to resume driving would be better than coasting a longer distance in N but using a small amount of gas idling the engine?

Could the button that turns off the injectors also cutoff the signal from the 02 sensor(s)? In that scenario, I think the car would go into Open Loop, right? Open loop may not be as efficient as closed loop, but it might be better than the ECU/PCM's reaction to the 02 sensor.

CarloSW2

[cfg83]

Bill in Houston -

Originally Posted by Bill in Houston

I'm suspicious that the scangauge recalibration might have been the biggest factor in the change you saw. Was the change in the right direction to explain your improvement?

That said, the grille block should help you coast a little faster, so there is some real improvement in there, most likely.

This is real easy to check if you don't use the ScanGauge for gaslogs. Just coast down the same hill with and without the correction factor.

CarloSW2

[diamondlarry]

Carlos, taking the O2 senor off-line could do the trick. I think that is one of the ways to overcome the mileage reduction I saw when I was experimenting with my MAP sensor mod.
Edit: Also, the correction factor could possibly account for the gain. I would sugest trying Carlos' idea and do back-to-back runs with the different SG values to verify it.

[savoF3]

Originally Posted by rGS

I was puttering along at 55 mph or less due to at least three traffic jam pockets and got bored on the way home so was practicing pulse & gliding up to 60 mph then back down to 55 mph. That resulted in a relatively astronomical mpg boost to 28.32 mpg. For a frame of reference, the posted speed limit on the highways for my trip was 65 mph.

Do you mean 28.32 for the whole trip? Ah looked at the gaslog, that's for one looong day on the highway. Pretty good including the endpoints.

At highway speeds I've been seeing negative value to trying to pulse and coast, though. The drag brings it down too fast. Let us know if you get some good comparative data and what your secret is to pulsing a minivan.

Godslow popimp.

[cfg83]

savoF3 -

Originally Posted by savoF3

I don't think it would be the grill block when you're in neutral. It's just your idle gallons/hour times you're speed. (unless you got coasting faster than usual.) Was it a blistering hot day? I had a great coast like this just yesterday and first saw 100+mpg. On my good coasting hill the car had already heated to where it reported 0.5gph in neutral versus 0.6gph. Bam, 20% difference right there. And who knows it might have been right on the cusp of rounding to the next tenth, so maybe it was a smaller difference than it appears. But 112mpg sure looks nice.

For engine-on-neutral-coasting, the GPH option is a good variable to observe on the ScanGauge.

In terms of rounding, you can change the units to Liters in order to see LPH instead of GPH. The LPH will give you better precision :

0.5 GPH = 1.89 LPH => 1.9 LPH on ScanGauge
0.6 GPH = 2.27 LPH => 2.3 LPH on ScanGauge

Conversely :

2.0 LPH => 0.53 GPH
2.1 LPH => 0.55 GPH
2.2 LPH => 0.58 GPH

I should make myself a handy conversion chart.

CarloSW2

[popimp]

Well I've coasted down the hill several times before with the SG2 and got about 75mpg. I guess at a -19.4&#37; correction this would equate to about 105mpg. 75 is about 71% of 105. With almost a 20% correction this would be about 91% give or take. So it was probably the correction factor.

[popimp]

Question about the P&G, or pulse and coast I guess. If I did the method of speeding up to 60 and using the coast function of the cruise control to drop to 55 then cruise back to 60, would this be the same as turning off the cruise then getting the speed back to 60 manually?