ScanGuage II question

<div class='quotetop'>QUOTE(G-IVSP Pilot @ Feb 12 2007, 12:59 AM) [snapback]388767[/snapback]</div>

There is actually a good thread over on CleanMPG.com about this very thing. Page 2 is where is starts to get good. Hope this helps a little.

I have Throttle Position, RPM, Coolant Temp, and MPG on mine at the moment.

 

<div class='quotetop'>QUOTE(G-IVSP Pilot @ Feb 12 2007, 12:59 AM) [snapback]388767[/snapback]</div>

I can't say my setup is better, and not having the mechanical training of some here, I'm not the best at helping with interpretation. But here's what I'm currently watching: RPM, coolant temp, throttle position (TPS), and ignition timing (IGN).

Of these, RPM is most helpful. I use it to keep engine speed in efficient ranges. Much of what I've learned about these ranges, by the way, has been from Hobbit's work. Skwyre7 has linked one of his CleanMPG posts, and here are direct links to two of his papers:

http://www.techno-fandom.org/~hobbit/cars/sweet/
http://techno-fandom.org/~hobbit/cars/heat...results-03.html

I monitor coolant temp for two reasons. First, I have my front grill blocked to accelerate and maintain engine warmups. It's not an issue at the moment, but during some of this winter's more moderate temperatures I was concerned about overheating. Second, I use it to gauge when to run the heat. It's been a relevation to see how quickly the ICE cools while running the heat and either sitting still or doing ICE-off glides. (You can lose 10 degrees or more sitting at a stoplight.) Of course the more it cools, the more it wants to run to stay warm when it doesn't have to for propulsion. So I try to avoid the heat unless coolant temps are at 170F or above (or my fiancee insists!).

TPS has a relationship to RPM, and I've been watching it to determine exactly what it is at various speeds. RPM changes constantly, whereas TPS is a little steadier. My hope is that I can find a range for TPS that will be easier to monitor than the always-fluctuating RPM.

I watch IGN briefly during startup. (As I elaborate, I offer a disclaimer: I may not be explaining this precisely or properly. I'm not a mechanic, and this is a lay person's possibly-flawed interpretation of what others more knowledgeable than I have written.) The Prius is at its least efficient during a cold startup as it tries to warm the ICE and catalytic converter. If you start driving immediately it seems to want to draw from the battery even with the ICE running, making this first phase of operation even less efficient. So some have suggested sitting for about a minute to let the ICE do its thing and warm itself up a bit before putting it in D, which is what I've recently been doing. During this warmup phase and while sitting still, IGN shows negative readings, which after about a minute quickly jump to positive. If I wait for this change to positive before putting the car in gear, it seems to have less of a tendency to draw from the battery during these early ICE-on minutes.

Occasionally I'll spot check MPG to compare to the car's display; they're usually within a MPG or two. I've watched engine load (LOD) in the past, and I may go back to that now that I've learned more about the car's efficiency ranges. Or switch from IGN to LOD on each trip after I start driving. Hobbit describes a low-RPM, low-load -- and low efficiency -- "loafing" state for the ICE that I'd like to get a better handle on.

 

Thanks for covering what I didn't have time to write, JimboK.

 

<div class='quotetop'>QUOTE(G-IVSP Pilot @ Feb 20 2007, 12:04 AM) [snapback]393122[/snapback]</div>

TPS in the 23-27 range seems to equate to RPM from about 1400-2000, though that relationship varies somewhat with speed.

After my last post, I've begun watching LOD again instead of IGN. First, I've noticed it has its own cold start-up sequence that lasts as long as what I've described for IGN: It starts in the upper 40s for the first minute or so, then drops to 30 or below. That's my cue to begin driving. From there, as suggested previously, I want to avoid low-RPM, low-load conditions. Exactly what constitutes "low-load" as defined by LOD, I'm not sure though. That will take more experimentation unless someone more familiar with it than I can step into this thread and help us out. For now, I'm aiming to keep LOD at least in the upper 40s during ICE-on cruising or acceleration.

Having said that, another CleanMPG member, "brick," reported substantially higher LOD readings at speeds and driving conditions similar to mine. One difference: the model years of our cars. I have a 2005, whereas he has a 2007 like yours. I'd link that thread for you, but I can't immediately locate it and I need to hit the road in a few minutes.

You'll notice something interesting as you watch coolant temperature for the first few seconds following startup. It will drop significantly as the warmer coolant from the thermos dumps into the rest of the cooling system.

 

quick scangauge question. Does anyone know if you can use it to turn on or off the prius built in alarm system. Or do you need a toyota scantool for that? Something I wanted to do but didn't want to mess with the dealer for it.

thanks,

-Peter B

 

<div class='quotetop'>QUOTE(JimboK @ Feb 20 2007, 06:20 AM) [snapback]393191[/snapback]</div>

Duuhh. It's the thread Skwyre7 linked above.

<div class='quotetop'>QUOTE(prberg @ Feb 20 2007, 07:38 PM) [snapback]393606[/snapback]</div>

Not sure what alarm system you're referring to. The anti-theft alarm? If so, why would you want that ability? Maybe I'm missing something here, but why not just turn it off or on the way it's designed: using the key fob. Regardless, I don't know how any OBDII scan tool would do that.

The SG will clear engine trouble codes and, in turn, turn off the Check Engine light.

 

<div class='quotetop'>QUOTE(efusco @ Feb 21 2007, 09:22 AM) [snapback]393877[/snapback]</div>

OK, obviously I've shown my ignorance. Please educate me, oh Great One. How will a scan tool turn off the (presumably anti-theft) alarm system, and why would someone use that method?

 

While the Scangauge2 can show trouble codes and has the ability to clear them, it does not have the ability to change vehicle computer settings like a scan tool can.