Any ScanGauge users here?

[Number_35]

Hello all -

I've been using ScanGauges in my vehicles since '05 - I still have my 1st-Gen one as a backup. (That's the clunky one that looks like a 70s Heathkit project.)

My current ones are both the ScanGauge II model, and my question involves the LOD (load) function. My understanding is that LOD displays the present power output of the engine as a percentage of the maximum power output possible in that gear. As a rule of thumb I downshift if the indicated load hits around 80%. I have no basis for this other than really wanting to avoid lugging the engine. I find it really helpful when driving in the mountains. Am I doing the right thing? As you all know, the 'net is awash with opinions. Some say that an engine is most efficient when heavily loaded.

Anyway, there are a lot of very knowledgeable people here, and I look forward to hearing your thoughts on this. Thanks in advance!

 

[earlyre]

I have run my scangauge II in my last 2 cars, but not familiar with that particular function, sorry.

 

[CharlieJ]

I've had a scan gauge II in my mazda3 for a few years now. It's automatic so it will downshift if the computer thinks the engine is lugging. But at WOT it will hit 99% load, it doesn't last all that long. It's pretty flat here on the FL coast so downshifting for hills doesn't really apply.

 

[55Test]

My brother has had his Scangauge II for years. I don't think he used the LOD function much either, but I wonder if that LOD reading is somehow linked to throttle position and MAP value?

 

[sciphi]

That particular feature is pretty useless in my Cruze. It will go to 99% with regularity, even when the engine still has more power available. So no, it's not something I use.

 

[CR94]

Originally Posted By: Number_35
... my question involves the LOD (load) function. My understanding is that LOD displays the present power output of the engine as a percentage of the maximum power output possible in that gear. ...
That's semi-close. I think it's supposed to be an estimate of the the present torque output as a percentage of maximum torque output possible at the current engine speed. I don't use it much. MAP is an actual measurement, and closely related.

 

[JHZR2]

LOD is inaccurate on all DI engines we own (three of them two Honda and one BMW)

 

[Johnny2Bad]

Originally Posted By: CR94
Originally Posted By: Number_35
... my question involves the LOD (load) function. My understanding is that LOD displays the present power output of the engine as a percentage of the maximum power output possible in that gear. ...
That's semi-close. I think it's supposed to be an estimate of the the present torque output as a percentage of maximum torque output possible at the current engine speed. I don't use it much. MAP is an actual measurement, and closely related.


If you are correct (I have no idea if you are) the point of maximum torque output is the most efficient point in the engine's operating range. Of course it's not the lowest fuel consumption, since you are working the motor, but it's the lowest fuel consumption at the highest load the engine can support. Any higher load will result in less efficient operation (lower percentage of fuel utilized versus fuel consumed).

If the motor is well engineered for road or work loads with a broad, flat torque curve, you can get efficient operation over a wide range of (engine) speeds. If it's engineered for maximum output then this point will be narrowly defined. A racing engine's gear ratios are often chosen so an upshift puts the motor at that RPM in the next highest gear. Regardless, even if testing shows a different RPM is best for time / speed / distance, it's always the start point for testing.

 

[TiredTrucker]

i have used the ScanGauge D on both my last semi truck and the current one. I like it. I don't use it for determining shift points and such, as I virtually memorized the HP and Torque curves of my HD commercial truck engines.

 

[GMBoy]

I used to use a scangauge but found that the Ultra gauge does more and costs much less.

 

[supton]

I bought mine before Ultra existed (or was popular), been in a couple of vehicles now. I find the mpg display to be only slightly better than eyeballing the gas guage and elapsed miles (from the trip odometer); once calibrated, I've found I must drive the same exact way, or it'll read wrong. It just spent all summer reading 1mpg low, with winter gas coming up it'll probably start reading right now--with no change in driving. Still 5% accurate I guess.

I use it mostly to watch ATF and coolant temp, with mpg displays for curiosity. If I ever get a CEL I'll be able to read it right away, but it's mostly for those two temps.

 

[IndyIan]

I found the LOD function in the scangauge pretty good on my cars without DI. My ultra-gauge makes the dash die occasionally on the Focus so I've stopped using it. I agree though that the MAP should be accurate in all vehicles and is a decent way to see how much more power is available.
Depending on your motor, above 2600-2800 rpm is probably OK to go 100% load fairly regularly, but under that you are right to be careful.

 

[dareo]

I had a Scangauge I, it eventually died. However the LOD feature was one of my favorites. It works great on diesels. My ALH TDI cars would be at 8 or 9 LOD at idle. Turn on AC and it goes up 1 or 2 points.

It actually saved me thousands of dollars once. I was looking at a Jetta TDI and everything looked good. It sounded good. I had it idling in the owners driveway, connected the scan gauge, saw a significantly higher LOD value, something like 18. I was immediately worried about the health of the engine if needed that much fuel to stay idle. I kid you not the engine literally seized in the owners driveway while we were talking about the car and its price. They did not take care of it and the scan gauge tipped me off.

 

[nobb]

Originally Posted By: GMBoy
I used to use a scangauge but found that the Ultra gauge does more and costs much less.


Good to hear. I also bought an Ultragauge over the Scangauge and am happy with the purchase. The ability to set high alarm warnings has already saved my engine when I blew a coolant hose.

I might pick up another for the other car.

 

[SHOZ]

There should be an absolute load parameter too. This one is more accurate. Peak load will also be near the peak torque of the engine.

But load is a function of rpm and air flow so you have to have the engine size correct and you Volumetric Efficiency too in the set up for the device.