Daox's MPG Modified 2004 Prius Build Thread

I like to start build threads for cars I own and modify to share what I've done. I have a few ideas in mind right now for the Prius, but I'm sure that'll grow over time. I must say, I'm really psyched to get started with this car to see what it can really do with a bit of tweaking. But, its going to take a while just to get used to driving this car.

I'm starting with a stock 04 with ~39,000 miles on it. I'm not sure what package it is, but it does have navigation and the JBL sound system.

First, lets see some pics!














Alright, the first mod is a bit of a teaser, but it is the first step. In case you can't read it, that says 50.

 

I don't mind the Toyota badges, but the dealership one I'd like gone. I'm not real sure on a good way to remove them though. Any suggestions?

 

Sunday morning I brought the Prius down to the Milwaukee Electric Car Club build day (we hold them every other weekend) to show it off and install an EV switch. The guys there were quite interested in it and asked a lot of questions.

A big thanks to efusco for writing up the instructions! His full instructions can be seen here:

http://www.calcars.org/prius-evbutton-install.pdf

The first thing I actually had to do was take apart the lower half of the steering column trim. In there, the headlight/foglight control stalk connector has a bunch of pins in it that have no wires going to them. I needed to pull one of the metal connectors out of it to use in the EV ECU plug since it doesn't have any connectors in the empty spots.

(took this image from the PDF instructions)




The next step was to take apart the the panels to get at the EV ecu. This is about as easy as it gets, no tools involved, just pull stuff. Its almost impossible to see in this picture, but there are three ECUs stacked next to each other! There are wires eeeeeeeeeverywhere.




Here, we got the connector out that we need to get at. The white piece on the connector pops up a little bit and allows you to put the connector I got out of the steering column into the plug.




The next step is to crimp a new wire to the connector and slide it back into the marked spot on the ECU plug. Very easy. (image taken from PDF again)




Here, I'm already starting to reassemble it. The connector is plugged back into the EV ECU. The white/red wire is the one I just connected to a blank hole in the connector.






On the white wire, I crimped a ring connector to go to the ground. I simply took out an ECU bolt and put this under it.




This is a momentary switch I had laying around. This connects the white and white/red wire and grounds the pin on the EV ECU to put you into EV mode. For final mounting I'll probably find another switch. Its hard to find a flat surface to mount something like that. Everything is so curvy it will never mount flush! So, for now its sitting in my favorite spot for switches... the glove box. Yay for zero cost mods.

 

Its been a while since I got to work on the Prius. Thats because I've been working on my electric riding mower conversion. Now that I got it mostly running, its time to start looking at the Prius again.

So, last night I made a grill block for the Prius. With the colder weather, its really starting to idle a lot more, especially when traveling at low speeds where the engine is off for a prolonged amount of time. Hopefully this will speed up warm up and help with aero on the highway. Unfortunately, I have no way of measuring any benefits since the Prius was broken into last week. My scangauge was stolen along with a few other items. Thankfully, the car was mostly intact (minus the passenger front window).

Anyway, pics!


Here are the fasteners I used. Thumb screws, fender washers and wing nuts. I went with a 10-24 thread and its works great. I used a very similar setup on my Toyota Matrix that the Prius replaced.




The block itself turned out okay. If you look, it gets sucked in a bit on the right side. Oh well, I'm not remaking it. Perhaps I'll find/make a spacer to push it back out.




I'm still debating how I'll block the top grill. I'd like to go with coroplast, but since its a V shape, it'll be a bit more difficult making a block for it.

 

I got a pic of the grill block in sunlight. The other pic is pretty dark. I also fixed the right side by sliding some wooden spacers in behind the right side screws. It looks much better.

 

I used coroplast (corrugated plastic) to make it. Its pretty inexpensive and easy to work with.

I was able to monitor my coolant temps this morning. I can definitely tell a difference. I was up to 150F a lot sooner than I normally am. It normally takes ~2.9 miles to get up to 150F. This morning (which is just as cold as it has been any other morning) it took roughly 1.5 miles to get up to 150F. This is a vast improvement. I only hesitate to say its amazing since it was the first trip with the grill block that I could actually measure.

Unfortunately, I also just put the snow tires on this weekend, so that'll probably sap up any mpg benefits of the grill block.

Also, since it is getting colder out, I started monitoring my 12V battery. I noticed it was down to 12.1V this morning! Looks like its time to replace it.

 

Currently I am not monitoring inverter temps. The ambient temperature is around 20F (-7C). So, I don't think I'll have a problem with anything overheating. However, I will be adding some sort of monitoring as it warms up come spring time.

 

Do you have any tips on how to monitor inverter temps? I've searched and see you can't get it via the scangauge.

 

I think I'm gonna pass on the CAN-View. A bit pricey for me.

The oven thermometer isn't a bad idea. But, I've been digging through Hobbit's page and I think I like his idea of tapping into the car's temp sensors a bit better. Even just a voltage readout should be able to tell me around where I am.

 

I just started recieving parts for my Enginer PHEV conversion. I broke it off into another thread though.

http://priuschat.com/forums/prius-p...-in-hybrid-electric-vehicle-4kwh-install.html

 

The PHEV is installed for those who haven't followed that decent sized thread. However, it has some major problems and needs some help in the battery management system department. So, I'm not getting a ton of use out of it yet. I am working with some guys to fix this and we think we have a solution. More info in that thread though.

I am posting here to say that I took some time tonight to install a block heater in the Prius. I've had it for months now, I've just debated using it since the Prius has a coolant thermos that holds warm coolant when the car is powered down. This coolant thermos works nearly as well as the block heater did on my Matrix, so I didn't see a huge need for it. Also, if the engine coolant is warmer than the thermos coolant temps, it won't dump the thermos coolant into the engine on power up. So, a block heater wouldn't be very useful, right? After a bit more thinking, I came to the conclusion that it definitely will be useful, and used right it will work very well in combination with the coolant thermos. I just have to run the block heater for a short enough time to keep the coolant temperature under what the thermos temperature is. That way, the coolant thermos will still dump into the engine upon power up, and I get the benefit of both. So, I installed it tonight and set the timer to run approximately 2 hrs before I leave for work in the morning. We'll see how this works.

Here is the kit contents. Installation is a pain in the butt, but not really that hard.




So, I now have two extension cords going to the car. When I get the phev kit automatic disconnect setup, I'll likely work on getting the arduino to be an onboard timer to power up the block heater too. But, that is a project quite a bit down the road.