Batman we have lean burn! 49.6 mpg!

[popimp]

Still haven't done a test drive but at idle the numbers are staying about the same here are my results.
All tests

TPS - 12
IGN - 20
LP - CLSD
MAP - 4.5

100 OHM
LOD - 23
GPH - .3
FIA - 335

150 OHM
LOD - 20
GPH - .3
FIA - 315

220 OHM
LOD - 22
GPH - .3
FIA - 290

330 OHM
LOD - 22
GPH - .3
FIA - 260

OPEN (DISCONNECTED)
LOD - 23
GPH - .5
FIA - -40
CODE P0113 (IAT SENSOR HIGH VOLT)

SHORT
LOD - 23
GPH - .3
FIA - 375
CODE P0112 (IAT SENSOR LOW VOLT)

CONNECTED
LOD - 22
GPH - .4
FIA - 105

According to my data this sensor makes no difference at idle.

[lovemysan]

The IAT sensor hack makes the car more load sensitive. Keep that in mind. If I were you I would put a 100 ohm and 330 ohm together and drive it for a day. Just pair the wires of the resistors together then leave 2 of the wires long to stab into the connector.

Warning! I'm no expert.

[popimp]

I took the van for a test drive using the 330 ohm resistor which is 260F. I think the SG2 uses the IAT to compute fuel usage. While driving to Home Depot my MPG was 35.5 with cruise control set at 30mph. I took it on the highway and was getting between 45-50 mpg going 50mph. The SG2 has to be flawed because I doubt this hack would boost the numbers by this much especially on a minivan.

[cfg83]

popimp -

Originally Posted by popimp

OK guys I went outside and put in each resistor. I only turned the key forward (didn't turn on van to get the temp reading of the resistors). The temp should be the same regardless because the resistance value is fixed (could change while driving due to heat).

My results

100 ohm - 335F
150 ohm - 315F
220 ohm - 290F
330 ohm - 260F

I did idle the van with the 330 ohm resistor in, I guess I should have done it with the others also (going outside soon). While idiling the 330 ohm resistor installed I got .3gph, with the stock sensor in I got .4gph, and with no sensor or resistor installed (open ciruit), I got .5gph. It usually idles at .5gph in N or .6gph in P. During this test the van was in closed loop for all 3 settings, according to SG2. Feedback please.

(Apologies for not saying this sooner)

I would try to use LPH and convert back to GPH. Why? Because the LPH will show finer granularity :

This table is my Saturn SW2, which idles at 0.3 GPH which is also 1.0 LPH
Attachment 656

Since the ScanGauge only shows data to the tenth, the GPH is not giving you as much "precision" as the LPH.

PS - I asked the scangauge guy to have 2 digits after the decimal point on the display for just this reason.

CarloSW2

[popimp]

The average for the trip ended up being 35.5mpg

[cfg83]

popimp -

Originally Posted by popimp

I took the van for a test drive using the 330 ohm resistor which is 260F. I think the SG2 uses the IAT to compute fuel usage. While driving to Home Depot my MPG was 35.5 with cruise control set at 30mph. I took it on the highway and was getting between 45-50 mpg going 50mph. The SG2 has to be flawed because I doubt this hack would boost the numbers by this much especially on a minivan.

You jogged my memory and I found that usedgeo speculated the same thing in his IAT experiment :

Intake Air Temp resistor experiment.
http://www.gassavers.org/showthread.php?t=2831

Originally Posted by usedgeo

... This mileage is just too darn good. It cannot be true. Here is an unpleasant hypothesis.

What is the chance that the ScangaugeII incorporates the IAT temperature into its fuel use calculation? ...

Usedgeo concluded that the Scangauge was being fooled in some way, .

To validate this one way or another, I would have to run a tank with one resistor, then keep switching off to other resistors for other tanks. Where's the gallons and time when I need them most!?!?!?!?

CarloSW2

[popimp]

I did read that thread. I just wanted to try it myself. Why would the IAT have such an impact on the SG2? What does the IAT actually do to then?

[usedgeo]

I don't want to discourage experimenting. Perhaps I went too far and the computer ignored the input. I never did get an explanation from Scangauge about how IAT could affect indicated mileage. I think Ron DeLong just had to discount the possibility.

I have been running real heated air and as Diamondlarry pointed out, when both water and air are above 200 it does not run all that well. I have never observed a timing retard on my car. My timing never makes it as far as some others report. The max I ever see is 34 degrees. The reported mileage is good though. Here is a recent picture of my plugs. It looks like it is running a bit lean. It has a slight miss at the warmest temps. I am hoping for Somender grooves to help with that. The ceramic is white but three of the ground electrodes are dark. There is a bit more about the plugs here.

http://www.gassavers.org/showthread.php?t=3927&page=2



I'll keep watching. It would be good to be proven wrong in this case .

[88HF]

Yeah heated metal and oxygen=bad. So complete burn is pretty important. Also some ECMs do add extra fuel to cool down combustion if they sense its too hot. Best expansion of ignited A/F from combustion is at ideal A/F ratio. Maybe using less fuel is the same as being easier on the pedal. Reducing fuel in A/F ratio should reduce efficiency of combustion.

[Bill in Houston]

Originally Posted by 88HF

Reducing fuel in A/F ratio should reduce efficiency of combustion.

Nah, not true. That is why lean burn gives better mileage.