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-   -   Batman we have lean burn! 49.6 mpg! (http://www.fuelly.com/forums/f8/batman-we-have-lean-burn-49-6-mpg-3302.html)

lovemysan 11-12-2006 12:49 PM

Batman we have lean burn! 49.6 mpg!
Wow wow wow. I couldn't believe my eyes. 49.6mpg to church and back. Friday evening I tested the resistors again just playing around. I used 110 ohm, 4.7k ohm and stock IAT on a ten mile stretch of highway. TPS is much higher with the resistor 3-10 points higher average between 55-60mph.

So today before church I popped in the 110 ohm and headed out. Conditions were

sunny and dry
Load was 3 adults, 1 child, baby junk, and my welder (100lbs) and jack/spare.

Trip there was 47.5mpg. Using beltway, speeds 60-70mph. No codfishing for first 15minutes(20 minute trip)

Trip back mileage improved to 49.6mpg. Driving through city. Lots of lights. Temp improved to the 50s.

Matt Timion 11-12-2006 12:56 PM

sweet! congrats!

SVOboy 11-12-2006 01:08 PM

Fo sho, saturns love that iat stuff.

omgwtfbyobbq 11-12-2006 02:07 PM

Nice. I've been debating about fooling with fuel trim, but from the emissions perspective it isn't very rosey.

lovemysan 11-12-2006 06:06 PM

Update so far I've been reporting today's current average. Not each individual 20 mile trip.

My average going back to church tonight was
On the return trip it increased to
53 mpg.

I'm stoked I didn't know I was going to hit these numbers this soon.
God Blesses.

cfg83 11-12-2006 08:48 PM

lovemysan -

Most egg-salad!!!!! I am trying extrapolate your result from cheapybob's resistor posting :


I used the above numbers to make an Excell spreadsheet. Would this chart be accurate to what you are doing? :


If this is accurate, then it looks like you are emulating an outdoor temperature of around 250 degrees F.

Am I on the right track?


repete86 11-12-2006 11:06 PM


I'm doing it after a few tanks with the PCV catch jar. I want to see how well it's working before I add something new.

lovemysan 11-13-2006 06:07 AM

yep 247f exactly.

cfg83 07-01-2007 12:20 AM

4 Attachment(s)
lovemysan -

I was asking saturnfans.com how I could :

Infer engine temperature from coolant temperature?

Hello -

What is more representative of the engine block temperature? The engine coolant temperature or the exhaust temperature?

... blah blah blah ...

To make a short story long, the thread segwayed to the reason I wanted to know the engine temp, IAT resistors and A/F ratios. Soooo, I did a test. It is *far* from perfect, but here is a picture of the data :

Attachment 651

Here are the defects with my test as I see them :

1 - I should have disabled the HAI (Hot Air Intake) in order to create a "stock" Saturn baseline configuration. Still, the HAI is "real" hot air, as opposed to the resistor, which *should* be in conflict with the 02 sensor.

2 - I should have a better and longer road to use for ABAB tests. A longer road might show the MPG go down over time as the ECU/PCM adjusts to the 02 sensor.

3 - I should do many more MPG tests, maybe 5 in each direction.

4 - I should have more fake IAT resistor settings for different temperatures.

5 - These are scangauge-based MPG figures. I can't explain it correctly, but the scangauge uses the "injector pulse width" to calculate MPG :

Scan Gauge 2 How it works

I thought it read the injector pulse width from the ECU and calculated fuel usage from that.
A shorter pulse width with each IAT resistor mod would imply lean-burn because the composition of the air coming into the car is the same for each test. Could the car be maintaining speed with less fuel and less air? The scangauge can't show me this for the purpose of this kind of test because it doesn't average MAP and TPS over time. I would need something like the CarChip for that :( .


However, I still feel good about the test because I think a clear trend is present.

The following is what really surprised me :

Attachment 652

The graph came out to be very linear. I was expecting at least some kind of curve.

PS - I don't think I should call this a true Air/Fuel Ratio. I should call it a Pseudo-IAT/AF Ratio because I am deriving it from other data, not the 02 sensor.


landspeed 07-01-2007 02:15 AM

Interesting... :D I wonder if I can have lean-burn on my car?

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