Got a prius, should be interesting to mess with....

[Blacktree]

An air dam can be used if the underside aero is bad. But there's a catch. In order for the air dam to be effective, it needs to come down very close to the ground. We're talking 2" of ground clearance, or thereabouts. That may or may not be an issue, depending on your driving environment. Side skirts would complement an air dam. But they would need minimal ground clearance, as well.

[ps2fixer]

Yea I expected the low ground clearance, which is why it needs to be designed to give when it contacts the ground. Up town the drives are steep enough to be an issue, besides that everything is pretty flat here.

The little I looked, the under side of the car doesn't look amazing for areo, it's better than average I'd say, but I see area's that could be cleaned up I think.

I'm still learning about the car. I set my cruise at 40mph for a mile and most of the way it ran on pure electric. Then I went 45mph, and of course charging the battery is going to take more effort. I'm not sure where the limits would be, but I suspect if I went 55mph, the load on the engine is in the ideal range for it's peak efficiency (has anyone looked into that?). If my thinking is right, running on battery at the slower speeds, then going a high speed hurts mpg more than running on the engine the whole time. The car doesn't know what we will do next, so for peak mpg there needs to be some manual control. The only way I know to make the engine run is to turn on the AC or demand heat from the engine besides touching the gas pedal enough to get it to start.

[hayden55]

Does it have a load bar like the gen 3?

https://i.ytimg.com/vi/Gj2J5_6zvvs/maxresdefault.jpg

[Blacktree]

No, the Gen2 doesn't have that. The Scangauge 2 has an engine load readout (in percent). That's probably the closest we can get.

[MetroMPG]

Originally Posted by Blacktree

But it would be nice to have a switch or a button to force the gas engine off.

There is. In other markets the car has an "EV MODE" switch, and it kills the ICE when you hit it.



It functions essentially like a conventional kill switch in a non-hybrid.

ps2fixer: you should do that mod, since much of your driving is short trips. You've noticed after it first fires up, the engine will not stop until it reaches a certain operating temperature AND you've come to a complete stop. The EV mode kill switch lets you take more control & save more fuel.

Adding a DIY EV Mode switch was a surprisingly effective MPG gain on my 2004 Prius. Made a noticeable improvement in short trip driving.

Read this post for more:

https://ecomodder.com/forum/showthre...tml#post499778

[ps2fixer]

I saw the "EV" mode somewhere, I think it was an xgauge or something, was interesting but didn't dig into it.

That's really interesting that you have to come up to temp *and* completely stop for the engine to turn off. I was wondering why sometimes it seemed like the engine didn't shut off even though it should. That's some weird programming I'd say, sounds like the ev mode button is right up my alley. I build harnesses, so fair chance I have the terminals to add to connectors if needed, or if I can source the connectors, shouldn't be hard to make a T adapter.

Having the ability to turn off the engine would be nice. Now the question is how to force it to stay on with out wasting power. Maybe I could tap into the AC controls and send the signal to the ECU that the AC needs to be on, and have a relay or something that would open connection, so the actual AC pump doesn't kick on, but when in "normal" use the connection is together so the HVAC controls work like stock.

Example case of where that would be useful is if you're going say 35mph in town and battery is charged so it wants to use EV mode, but you know you're going to be driving 55mph+ shortly, you don't want it trying to recharge the battery while at the higher speeds.

It would be really nice to control when it does the recharge too.

I've played a tiny bit with the "B" mode. Is the only benefit to that mode more regen? It does slow the car down faster, so right at the end of the coast a "B" mode "brake" might regen more than the brakes would do? I suspect the effect is tiny overall but an interesting concept at least.

Anyway, I scanned over the Toyota hybrid system wire diagram and engine control and didn't see any switches that sounded anything close to an EV mode. I'm pretty sure these wire diagrams are world wide, I've at least seen notes in them for Fed, California, Canada, and Brazil for different vehicles. I tried to google for the ev mode but not a whole lot came up, just some people mentioning a kit and people taking about using it.

Just found this when looking for a kit, site looks old and some links are broken. There's no instructions sadly.

https://www.autobeyours.com/EV%20But...or%20Prius.htm

Oh found another page on the site with instructions it looks like.

https://www.autobeyours.com/EV.htm



I'm pretty sure I have those terminals on hand! Sounds like it's just a wire to ground, so should be simple to wire up. I checked my wire diagrams and checked a few different points and it looks like the ones I have don't have the EV mode wire in the diagram. I haven't quite figured out the exact coverage for those diagrams, I thought they were likely world wide, but clearly the EV mode pin is missing so it's not world wide, maybe North America, or Western world (North + South America).



Small update for the thread, I messed around driving up down a bit for family today, yard sale and such, and reset my trip at my parent's house and went 70mph on the highway to show them the mpg drop at those speeds and noise levels and such. Round trip with a couple stops it indicated 50mpg. Down to 2 bars on the gas gauge, probably should have filled up on the way home, but instead of taking the express way, I took the back way like I normally do from that part of town which doesn't really have a good gas station to fill up at. Should be interesting to see how the mpg compares to the rough average of what I've seen seeing on the screen, and the whole bladder tank think.

Also, I just picked up a small trailer for $80. Decking isn't anything special, but it looks like it will work well for the prius if I need to haul something too big for the car, but small enough a truck isn't needed. Makes me want to design it so it's somewhat part of the boat tail shape to offset the extra drag. Either case, I've been needing a small light duty trailer for a while, the 15,100lb rated equipment trailer is a bit overkill for most things and is around a 25% drop in mpg for my diesel when empty.

[Drifter]

Gen2 warm up stages (stage 4 happens after you come to a complete stop for 5-10 seconds): https://web.archive.org/web/20100206...ence051408.pdf

B-mode also uses engine braking since you will charge the battery pretty quickly on any extended downgrade.

[MetroMPG]

Originally Posted by ps2fixer

That's really interesting that you have to come up to temp *and* completely stop for the engine to turn off.

Since your original post suggests you may be doing rural driving (assumption based on ~50 mph speeds), you need to be sure you're not in a situation where you manage to get onto the highway without reaching the warm-up stage where the ICE will stop when the accelerator is released. Otherwise you could end up driving 10 miles with no ICE-off ability.

sounds like the ev mode button is right up my alley.

Yup!

I've played a tiny bit with the "B" mode. Is the only benefit to that mode more regen? It does slow the car down faster, so right at the end of the coast a "B" mode "brake" might regen more than the brakes would do?

As Drifter says, B mode spins up the ICE for extra drag. Don't use it for efficiency gains!

And B mode doesn't give you any extra regen current than you could get by simply pressing the brake pedal.

Friends of mine bought a 2016 Prius new, and were told by the salesman that B mode fed "extra" power into the battery. So they were often shifting to B mode when decelerating. Doh! I set them straight and gave them some basic ecodriving coaching. They've averaged high 50's MPG with the car the past 5 years.

[ps2fixer]

That pdf is pretty neat, kind of crazy you have to drop to enter stage 4.

Driving home from my parent's place is roughly 8 miles, the engine hit a peak temp of 172F if I remember right. I figured around 160F would be counted as warmed up, it took something like 3 miles for that temp. Upper grill is still open. I drove 30-35mph at first, then 45mph the rest of the way, short trip averaged to 50mpg. Guess I won't be seeing 50mpg from short trips at 55mph unless I have a full boat tail.

I figured the "B" mode wasn't good for mpg, it seemed like I could feel the engine turning over so figured it was engine braking too which is wasting energy, same as brakes effectively.

I got my scan gauge in today, added in the GAS and SOC xgauges, 2 pips on the gas gauge and I drove a ways on it and it was 25% yet. No clue how full it was for the first fill up but if I keep track of that, I suspect I can keep track of the bladder effect, maybe use the gas % to get the fill ups more consistent. I'm not sure how accurate it is though.

SOC is pretty interesting, looks like my car hangs around 59% quite often. Driving home on my dirt road at 20mph it takes roughly 2% not counting the take off (I thought of it as I made the turn so had to flip through the gauges to see it). It is a bit down hill then up hill for my drive way, ended at 57.5% if I remember right.

The MPG on the scangauge vs the in car display is very close to being the same. Clearly the scan gauge isn't calibrated yet to the car.

Looks like the rpm I was targeting was around 2100-2200rpm just a little high to be most effective, it's so quite so I guess it's kind of hard to judge rpm by year lol.

I'm thinking sealing up the front end as much as possible, and having some sort of slider door to allow for extra cooling in the lower grill block would be the best route to go. Seal front, under belly, and hood so any heat in the engine bay can be used to help heat the engine up quicker. On long trips might need to open the slider if temps rise too much. I think I'll probably need to buy one of those chinese digital thermistors to keep an eye on the inverter temp.

It would probably be pretty neat to get some digital gauges that I could control with a micro controller and setup analog gauges for engine temp, hybrid SOC, engine rpm (or load). The A pillar is a common place to throw gauges like that, shouldn't be too hard to tap into the signal wires without effecting the reading to the computer. With it already in the car, it could intercept the signals and adjust the signals for what the computer actually sees too and what the scan gauge would say. Like could make the engine temp "sticky" to the higher mpg modes so it runs less. As long as the computer runs in closed loop, I think it would be safe to spoof the temp warmer on the engine temp say +20F or more near the line where the modes change or make a lookup table. As long as it doesn't have a dead spot in the temp range it should be able to self tune the differences out and run like normal once it learns it.

I'd also like a "cruise" control that is stead pedal instead of steady speed, I suspect that would give the best mpg in the prius in most cases, let the mph change instead of the engine load/rpm and battery charge level. Idea is less using the battery at 41mph+ the more efficient it will be.

Either case, I think the Prius is good enough to keep. I think my 2004 Matrix will be going up for sale soon, I got a pretty good deal on it, so I probably can turn a profit reselling it. It had a trans line leak, pretty simple fix.

I haven't looked into the brake system too much on the wire diagrams, but I suspect it works somewhat similarly to the accelerator position signal. I'm not sure how much physical brake I'm using vs regen, clearly the brakes need to be used every once in a while to keep rust off them and such, but less use of the physical brakes and more regen would be more efficient. Just a simple button to hit to spoof the brake signal might be useful. The brakes are super good on the car, so I'm guessing the regen is working really well. My truck and my Lexus brakes feel like complete garbage compared to the prius lol.

Anyway, lots of ideas, just have to take action on what I can get done. Adding the micro controller in the car would be interesting to play with.

For my trips, roughly this is my travel pattern

3 days a week shipping out packages (10 mile round trip) all 55mph roads
1-2 days a week - I go up town, around 30-40 miles round trip. All 55mph roads till town then most are 45mph, couple spots are 30-35mph. I know the lights fairly well so I generally know if I'll make the light or not for coasting and such.

The road I live on is dirt (hard packed but bumpy generally, not much gravel in the mix). I'm roughly 1/4 mile from the corner, and it's up hill slightly from my house, maybe like 15-20ft higher than where my driveway is. My driveway goes up probably 5-10ft higher than the road with a dip in the middle. For the most part, my area is flat, minor small rolling hills, but generally no more than a 30ft change in elevation across a mile.

Anyway, I think my main focus will be the front of the car and main target would be areo and quicker warmup times, seems like the most logical starting point on this car.

[ps2fixer]

Finally got to do a fill up in my car. I did it to two clicks at the pump and it seems to be pumping a lot slower than it was before. Scan gauge said 97.5% full. Not sure what the original fillup was to, but based on the miles went and gallons, it ended up 46.25mpg. I'm guessing I got a bit more gas in it this time than last time though. I've done a lot of messing around, poor driving etc at the start so understandable it's not quite 50.

For the P0420 code, I did some reading and people said a cat cleaner can work well sometimes if the cat isn't completely toast (melted). Put in Cataclean today and got some miles on it then filled it like the instructions says. Not cheap stuff, but it appears to be working so far. Went on a 160 mile round trip or so and check engine light hasn't come back yet.

Talking about the trip, since I reset the scangauge and the display on the car about the same time, I can compare their readouts. It looks to be within about 2% of each other.

Pretty much every trip on the scan gauge (few stops along the way) I hit 50mpg give or take a little bit and that's traveling at 60mph. Trip home had no stops, going against the wind more, and ended up at 50.1mpg on the scangauge (55mph on the country roads), so it is possible to get 50mpg going around 55mph with this car if you ignore the cold start warmup process.

My grill block seems to not be holding up too great, getting a bit wavy, the tape is coming apart lol. Kind of expected though, just was a temp thing anyway.

I noticed the engine seems to cool off super fast on this car. Even with the lower grill block after about 30 mins it was already down in the 140's. I think sealing up the front end/engine bay a bit should give some reasonable benefits, then again, I'm used to a corolla engine that ran slightly hotter, around 195F and cast iron block and more coolant I'm guessing, so it would hold heat for quite a long time.

I've been mainly driving on the cruise control, it's always making the engine run fairly hard to catch back up for tiny hills in the road and such, so I think the load based cruise will make a massive difference. Being able to have the pedal perfect for engine off coating would be nice too with say a push of a button. EV mode button for sure would be useful, I found a fair number of times when I was costing down and it didn't want to turn off the engine untill stopped. It's weird because sometimes it will with out having a complete stop since startup for the 5 secs, there seems to be a timer involved or something as well or the stop route for mode 4.