I still wonder about the "CAT" temp. I never read much over 900 degrees Fahrenheit. I am under the impression that a CAT would normally reach temps of 1000F up to 1300F. I never read temps that high.

That is why I suspect the sensor is on one of the O2 sensors and is reading Exhaust Gas Temperature.

Just got my ScanGuage and love it! I have one potentially complicated question though...

I am looking for a good way to monitor fuel efficiency with a further normalized value than MPG. Let me explain...

There is a common myth that having a lead foot kills MPG, however this is not entirely true. If you floor it from a stop, yes, you will see MPG plummet, however you will reach cruising speed sooner. If you are very light on the accelerator, yes you will see higher instantaneous MPG for the acceleration, however it will take longer to stop accelerating and reach your cruising speed (where MPG is highest). I actually did a test to get a feel for the difference between the two:

Over the course of one tank of gas, I floored it out of every single stop. During another tank, I was very light on the accelerator. The difference in overall MPG between the two tanks was negligible, in fact the lead-foot tank did about 1 MPG better. I could speculate that this was because when you accelerate faster, you level off and reach cursing speed faster and therefore spend more of your trip closer to the optimum MPG speed (somewhere around 55mph +/- ?). Maybe it was a separate factor, but the bottom line is the difference is negligible and within statistical error.

So real-time MPG does not obviously tell the whole story, and I am looking for a good way to incorporate the above factor (how hard you accelerate AND time/distance spent accelerating) into my observations so I can get a better feel for fuel efficiency and driving habits. I'm guessing it would be some sort of multiplicative value, e.g. MPG*TPS (throttle). Using this theoretical number as an example, if I am flooring it out of a stoplight (100% throttle) but am at 10 MPG, the value would be 1000 (100 throttle * 10 MPG). If I am cruising on the highway at say 55 mph which let's say uses 50% throttle and 20 MPG (just making up an example), the value would also be at 1000 (50 * 20). If, however, I was really hauling at a 110 mph cruise, I might use 75% throttle and get 10 MPG. Now my theoretical value is only at 750 (75 * 10). Seeing this value drop from 1000 to 750 tells me that a factor other than temporary acceleration has impacted my MPG. Yes this is an obvious occurrence going fast on a straight open highway, but it is not so obvious at all with other cars on the road, constantly varying the gas pedal when the MPG jumps all over the place. I hope this makes sense. My example of MPG*TPS seems to be close in theory to what I want in the way it scales, but it's probably not quite right (if I wanted to gauge true real-time fuel efficiency).

Is there some sort of other number which gauges this already, or could I program my own? Can you make an XGuage which multiplies two readings together?

If I'm driving the same route, avg MPG for the trip gives me the kind of feedback I'm looking for since it takes out the acceleration factor, but it's not instantaneous and therefore hard to improve real-time.

I've got the scanguage with all kinds of xguage's on it, and it has helped my mpg (27.1 max on a full tank @ approx 75mph).

I never use the throttle percent because I can't see anything it helps with.

Now a vacuum guage while driving will come very close to telling you the pressures inside the engine which some guys use to watch mpg.

More than 30 years ago an article in the auto mags described driving hard to 2k rpm, then easing it around.

What's happening is the volumetric efficiency goes up a lot as the throttle is opened creating more compression.

I'ts been my habit since then to open the throttle about half to accelerate up to speed limit, then, coast it down to the next light.

I can feel a good kick from compression and or timing advance on most cars at about the halfway point, and hypermilers call this pulse and glide.

I don't wear brakes much either; it's the guy behind me that keeps his twitchy foot hitting the gas even though he can see that I've got a line in front of me.

Which gauges do you use the most?

I'd like to know this too. I've just been using Ave MPG, Instant MPG, Water Temp and then for the 4th, I switch around to the other gauges.

X guages - ATT(auto trans temp), CAT(cat temp), MAF(mass air flow), HPR(horsepower), MTG(Miles to go on avaiable fuel)

I have 225/40r18 tires which gear down the speedo 3.3% so I put the Scanguage right behind the steering wheel, set the wheel as high as it goes to obscure the real speedo.

Top left is speedo, bottom left is water temp, top right is ATT, bottom right is AV mpg which I change to MTG when I'm thinking about which town 30 miles apart is the better fuel stop.

Sometimes on track day I put the water and trans temp on the left, and the maf and hpr on the right.

Of course the HPR is not accurate, but its consistant to compare state of tune.

Sometimes I cycle through the trip functions to see top temp, speed, or mpg for the day.

Truly the best car toy, I've ever had!

40w8,

What code do you use for the auto trans temp? I tried one a few years back and it didn't work. I actually have a Prosport gauge installed to measure that.

Also, what year is your car? I wonder if it works for the 6-ports but not the 4-ports.

Google: Scanguage II ATF TEMP CODE

I put them up seperately in the AT thread to be able to find easily.

I needed to keep from damaging the new one I got at 23K, so I bought the biggest Derale cooler that would slide into the front of ac condenser without taking spoiler off.

My Derale 18,500 BTU bolts where the grill was, and on a hot 98 deg day water was running 194 and trans 194 on the open highway 80-100mph.

When I stopped and measured with infrared gun, one side was 172 on the cooler, and the out was 158, so I got a 14 deg reduction from normal design.

I plumbed it like the instructions: line out from stock radiator goes to new Derale, then to trans.

That's called series plumbing.

I'm thinking that at some point there might be some restriction to flow, so I'm going to replumb paralell so that the trans fluid goes to both coolers, then, back to trans.

I'm pretty sure I'll get max cooling on track which is where I want; I saw 235 deg (quits shifting at 249)with no extra cooler, but haven't been to track for the new 18,500 cooler.

Thanks!

Yeah, I ended up running two NAPA trans coolers to keep the fluid cool for track days. One is the smaller "stanard" size. The other is the large RV size. Works great on the track. Only problem is during the winter I get way too much cooling, and if I try to shift while driving aggresively the transmission slips. Gotta figure out something for this upcoming winter to block the airflow to the trans coolers. Not sure if I'm going to go with pieces of cardboard with some zipties, some racer's tape, or what.

Why don't you plumb the coolers parallel with a valve or two.

When cold weather comes just turn the valve off, and the stock cooler will flow as usual.

I only start my car if its gonna be hot enough to track 60-90 deg f so I probably won't need the valve, but I've already thought about it.

So what are those atf temps with all that cooling?

Is that a 6spd, and what lead you to put all that cooling in?

I'm guessing that the lowest temp on track with my setup will be 220deg f, which I think is fine for only 4 days a year.

Bump

40w8,

Since we are going off-topic, I sent you a PM.

In another thread, there was some debate about how accurate the ScanGaugeII is regarding fuel economy readings.
Since my experience was that the properly calibrated ScanGauge is spot-on as far as the volume of the consumed fuel is between fuel-ups, I expected the displayed MPG values to be also perfectly accurate.
So I decided to log miles driven and the (average) trip mileage shown by the SGII. My theory was that at the end, I would just calculate how much fuel should have been used based on the MPG value for the trip and the actual miles driven. Adding these up must match the pumped fuel volume at refill. If it does, then we can conclude that the shown MPG values for the individual trips are also correct.
Attached are the results of about a half tank used.

The pumped fuel volume was exactly 7.03 gallons (Date is 9/23/2011 in my Fuelly log). I used the same pump as the previous fill-up, to eliminate differences in pump shut-off points.
As suspected, the ScanGaugeII is perfectly accurate.

Ok, sorry to bring an old thread to life but I have had my scangauge for about a year. I have been able to get the gauges I want to display except the oil pressure...did anyone ever get that gauge figured out?

I used to have it mounted on the steering column but have modified the ash tray area and have it now mounted in there flush so that the door still closes to hide it when I am parked and away from the car. With it in the open, it just leaves it visible for some douchenozzle to break in to get it even though they have no clue what it is.

You cannot do oil pressure, the factory oil pressure switch is basically an on/off switch, it just tells you if you have oil pressure or not.

That sucks...is there a way to know if the pressure is good or not?

Your factory gauge. If pressure drops you will know it right away anyway by the catastrophic failure of your motor.

LOL, after 6 engines...I know that feeling ;)