WARNING! This hack could damage you engine and void your warranty if not used properly! I originally posted over at http://priuschat.com/forums/private-sales/60906-coolant-temp-hack-better-mpgs.html But I thought some Prius owners here may be interested. I recently bought some POTs and knobs to fine tune my coolant temperature hack. I found the right combination of everything and I have a few extra parts I would like to sell. I will only sell to you if you understand that I will not be held responsible for any damage to your car in the result of using this hack. I will also only sell to you if you have some way of monitoring the coolant temperature either with a ScanGauge or a CAN-View. Another reason I require you have a ScanGauge or CAN-View is so you can clear any code you may get. It is possible that by using this hack you will get a trouble light on your dash and you will need a device to clear the codes. The car may not go into S3-S4 mode until the code is cleared. This hack works by sending a fake coolant temperature to the ECU. See this topic for more information. http://priuschat.com/forums/prius-modifications/52448-coolant-temperature-hack-better-mpgs.html I'm using a 1k linear POT with an SPST switch and a 520ohm resistor in series. This will allow you to adjust the temperature easily to your liking. The best way I found to use this hack is to let the car go through stage 1. After stage 1 let the car warm up to about 105F. Once it reaches 105F you can turn on the hack. Adjust temperature to about 165F-175F. Now you should be able to get into S3 and S4 easily. With this hack you MUST monitor the temperature especially if you are traveling on the highway. When the hack is turned on and you have it set to 170F the actual temp may be 130F. As the temperature rises the fake temperature will rise with it. So if the actual temperature is now 170F then the fake temp would be 210F. You do not want the fake temp to be above about 180F so you will have to continuously turn down the fake temp until you eventually just have to turn the fake temp off. If you let the fake temp get too high ( above 210F ) your dash will light up with all kinds of warnings and the fans will start to kick on so you better be willing to monitor it while you have it turned on! Since this POT has an on/off switch this makes adjusting pretty easy. You will start out in the very left position. You will turn the POT clock wise until it clicks. This click is the on/off switch turning to the ON position. When you first turn it on the temp will start about 30F degrees higher than the actual temp. Just turn it up to about 170F and monitor it. As you turn down the temp you will hit the off position. You will hear and feel it click just like when turning it on. Its that simple. So here is what I'm selling. I have 4 POTs, 2 different styles of knob (4 total) and only 2 knockouts for the dash. Each knob has set screws to attach to the POT shaft. One knob has a skirt the other is just a straight knob with a pointer. You can select what knob combination you want. First come first serve. SOLD OUT I accept paypal for payment. Each will come with the 520ohm resistor soldered on and two wire pig tails. The dash knockout kit will come complete with knob installed on the knockout like the picture below. If I forgot anything I will try to update this first post. If you have any questions feel free to ask them and I will do my best to answer. The only thing I guarantee is that the hardware I'm selling will work when installed and used correctly. When used properly this hack can improve your fuel mileage. If you own a plug in Prius and you have a short commute like me this hack will help a lot! Here is the knob installed in the dash. Its is the perfect location for this hack. Here is the dash kit. Here is what the knobs and POTs look like.
Just sold one. My stock is down to... 1 AVAILABLE! POT with dash knockout and knob. - 35$ Shipped to the lower 48 States. 2 AVAILABLE! POT with knob only - 30$ Shipped to the lower 48 States.
Jay, I plan on giving you a call one day. From the reading I've done, I'm unlikely to do this hack until I convert to PHEV. When I do though, it seems like it will be nearly essential given the limited ICE use that will likely occur. Thanks for doing this.
I now only have 1 POT and one of the regular knobs without the skirt. If you want me to mount it to a knock out you will have to send me yours or you will have to do it yourself. I'm still using the other one on my car and don't want to sell it just yet.
I finally wired up one of these since I had my panel out and its harness brings the ECT lead up anyways. Using a 5K pot and series 470 ohm limiter; it can simulate up to about 95C, just shy of when the alarms go off. If I bring it up to just over 70C during stage-1 warmup, I can just pull to a momentary stop at the first intersection in my neighborhood and let it dance itself right into stage 4 and then not have to worry about the EV switch from then on. . I don't know why I didn't do this two years ago... . _H*
I noticed you'll be at the fuel economy challenge in Fonda...you know..you could've waited just another couple months
I'm no longer selling this hack because I'm all out of parts. I will be working on an automatic hack based on a design made by jstcd which is located here http://priuschat.com/forums/gen-ii-prius-modifications/36342-another-thermistor-hack.html#post628184 in post 11. I have permission to use his design and will be producing only a few. I just ordered the parts today and should have a prototype built in a few weeks. After a month or two of testing and everything works OK I will make an announcement of the price and how you can get one.
