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Daox 11-24-2012 10:43 AM

Daox's Grey 2004 Prius
4 Attachment(s)

As I mentioned in the my black 2004 Prius build thread (which met an untimely demise :(), I replace it with a grey 2004 Prius that I picked up earlier this week. Thankfully, I was able to remove a bunch of the mods I had done to the black Prius, so it'll be a process to reinstall them on the grey Prius.

To facilitate that, yesterday I headed over to BenNelson's house so we could both do some winter prep on our Prii. His build thread is here if you're interested:

We got a few things done on his vehicle, and then we moved on to mine. We started by installing an OEM Toyota block heater for the vehicle. I don't really have any good images of it because all you'd really see is me laying on the ground with my whole arm stuck up into the engine bay. I couldn't even see what I was doing, I just had to feel around to get it done. But, I've installed four of these block heaters now (one on my Matrix, one on Ben's Prius, and two on my Prii), so it wasn't a new experience.

The next thing we worked on was grill blocks. We started out with the standard pipe insulation for the upper grill block. I had never previously done this, but it turned out quite well, and looks pretty decent on a grey car.

We also made a lower grill block identical to the one I had on the black Prius. It consists of two blocks of wood what are screwed together to pinch the grill. The only difference is we zip tied the ends of the grill block to seal things up better. Details on how I mounted the original grill block can be found here:

I DEFINITELY noticed the full grill block advantage on the way home.

On the way to Ben's house there aren't any roads where the speed limit is above 50 mph. The temperature was about 30F on the way out and 28F on the way back. On the way there I struggled to maintain 160F+ coolant temp. Every time I slowed down for a town or something I had to cut the heater fan back to low or off. If I wouldn't, the coolant temp just plummets. Then, while traveling 45-50 mph I was able to kick the fan speed up to max and get heat. With this, the car would just stay warm.

On the way home, I was easily able to blast the heat during the higher speed stretches (thankfully after a chilling day of working on cars heat is much appreciated). On the coasts through town, the engine didn't cool off nearly as much, and I was able to keep the fan speed higher.

I don't have the scangauge calibrated at all yet, so I can't give any mpg numbers, but it was a noticeable improvement.

There is still a ways to go before this car is up to the black car's specs, but this was a substantial jump forward to bridge the gap. I also never had the upper grill blocked on the black car (always planned to, just never did) and I can already see the advantage it is going to give me in winter.

bennelson 11-24-2012 02:02 PM

Wow, upper grill-block looks great in those photos!

I noticed the full grill-block made a big difference this morning when I was doing a test drive.

Here's several silly photos of Tim working on the car.

I was impressed at his triple-jointed skills of getting that block heater in with the car only raised about 8 inches off the ground on a pair of ramps.

It was nice having somebody else to work with on the cars (and some heat in the garage!)

For the foam of the upper grill block, we cut pipe insulation in half the long way, and then folded THAT in half. That put the radius of the foam on the outside and the foam is always trying to UN-FOLD itself, which pulls it IN to the grill. It really seems to hold well.

MetroMPG 11-24-2012 02:32 PM

Agreed - the foam pipe insulation upper block looks really good on the grey car.

Glad to hear it made a noticeable improvement too.

Daox 11-24-2012 05:00 PM

3 Attachment(s)
Another day, another mod put back on. This morning I installed an EV switch. I have my left over one from the black car, so it was mostly just a matter of getting a connector pin out of a connector and inserting it into the right pin on a different connector. The whole install is documented very well in this pdf:

Its simply a momentary switch and some wire.

You plug one end into the proper ecu pin, and the other goes to ground. Very simple.

I've also been tinkering around with a coolant temperature hack. I had this on the black car, but it never worked right. I made a few changes and it seems to be getting closer, but its still not working right...

Daox 11-25-2012 04:40 PM

Just wanted to stuff this in the thread. Ben made a great little video of us doing the grill blocking work to the cars:

mechman600 11-26-2012 12:00 AM

Great thread.

Daox 11-26-2012 08:34 AM

Thanks mechman. Its a fresh start and a chance to rethink and improve the original mods I did to the black Prius. Stuff that worked well I'll keep and hopefully even improve. The lower grill block is a good example. I reused the main design, but some brainstorming with Ben found a way to improve it in looks and usefulness.

Speaking of improvements, I was really able to realize the benefit of the top grill block this morning on my commute to work since its a much more familiar trip. Combined with a preheat of about 2hrs with the block heater, I was up to temperature almost as fast as summer! Within one mile my coolant temp was up to about 140F, and it was 25F out this morning. In summer it is up to about 155F at that point.

Daox 11-29-2012 12:57 PM

I'm finding that I like the full grill block so much that I'd like to keep it around year round. However, running a full grill block can definitely be a problem in summer. So, I've resurected my old thread on an arduino controlled automatically actuated grill block. The old design for my Matrix didn't work out. But, I think the new design is simple to make, scalable for whatever application, and cheap to make too. I have another thread started to show the progress on it here:

Cobb 11-29-2012 01:41 PM

I cant speak for the prius, but the Insight doesnt mind having 3/4 of its grill blocked even in 100+ degree weather with ac use.

Looks like a neat idea and way to make a few bucks on the side for others. :thumbup:

Daox 11-29-2012 02:03 PM

In previous years with my black Prius I just ran a lower grill block year round. It really does block a lot of area. However, I'm now seeing the benefit of the full grill block warm up times despite the cold weather. In summer it will be nice to have even faster warm up to allow engine off operation sooner.

Cobb 11-29-2012 03:17 PM

I tried it with tape one time and just kept adding til it was completely blocked and used my sg2 to watch temp. Ive also added a bottle of water wetter to the antifreeze and put the amount needed to be removed from the rad into the over flow bottle.

Yeah. does wonders for acceleration at 50-70mph with the seat of the pants dyno.

Its also nice to have the heat a degree from max and still maintain normal operating temperature, fuel economy and other IMA behavior when its freezing or below out. I have MS so heavy clothing is out of the question.

Daox 12-14-2012 01:48 PM

For the first time since installing the grill block I had the car on the highway for a reasonable amount of time. I noticed the full grill block certainly did its job. The ambient temperature was around 45F out. It took a little while, but the coolant temp just kept going up and up until around about 204F / 95.5C the radiator fan kicked on and the coolant temp quickly dropped down to around 190F. After that I turned the heat on and that kept the coolant temps in check. At lower speeds (45mph and less) I would be willing to bet the cooling fan would probably never come on.

Looks like that actuated grill block will be coming in handy every once in a while even in winter.

Cobb 12-15-2012 06:31 PM

How are the other cooling systems doing? I think I heard or saw a second cooling system for the inverter and maybe another for mg2 if I am not mistaken?

Yes, its nice to have toasty heat in freezing temperatures and still able to use ev mode, autostop, etc from a hybrid. :thumbup:

Daox 12-16-2012 09:24 AM

As it is right now I'm not monitoring inverter temperatures. After this experience I will be looking for some x-gauges to program into the scangauge to try to get something. I've been told at the least I can get MG1 & 2 (motor generator) temperatures. However, after hearing what kind of temperatures they operate at I'm not really concerned much.

bennelson 12-16-2012 10:15 AM


Let me know how to set up my scanguage for the inverter temperature when you do!

RobertSmalls 12-16-2012 02:08 PM

I found this very long list of X-Gauges for the Prius. The four that I've tried so far appear to be working correctly.

Cobb 12-16-2012 07:59 PM

FWIT I sat in my insight with a space heater trying all of those included ones for afr and lean burn, etc and none of them worked. :eek: This is with the latest update too.


Originally Posted by RobertSmalls (Post 345730)
I found this very long list of X-Gauges for the Prius. The four that I've tried so far appear to be working correctly.

Daox 12-16-2012 08:02 PM

Codes are different for every manufacturer and probably even differ from model to model in some cases.

F8L 01-05-2013 10:37 AM


Have you been able to monitor inverter temps yet?

I have a 2012 Prius now and I used the insulation foam to block 100% of the lower grille (radiator) but left the upper grille (inverter) unblocked. Under normal highway driving at 29F-55F and <70mph my coolant temps are 191-195F. Going uphill on my morning commute temps may get to 198F as long as temps stay below 50F. At 60F I saw temp rise to 202F then drop back to 195F pretty quickly. I feel I have a good handle on coolant temps now but I am concerned with inverter temps and my Scangauge has not been updated since 2006 and won't accept xgauges for my 2012.

I made the mistake of driving to LA at 75-85mph with the grille block on and when I hit the grapevine my temps climbed to 211F before I realized there was a problem. Despite temps in the low 50s, the grille block was obviously too much. Just a reminder so you guys don't do what I did. Make sure you have the tools needed to remove your grille block at a moments notice. ;)

Daox 01-05-2013 07:18 PM

I still haven't bothered to try anything out. My daily commute is 7 miles at a top speed of 45 mph. In winter I get up to temp, and all the excess heat goes to heating the cabin. There is no chance of overheating.

That being said, this weekend I took a trip across state. Half of the trip was 55 mph country roads. With the heat set to max hot, and the fan on about 1/4 speed the fan came on about 3 times. At 60 mph the coolant temps rose a lot faster and I needed to pull one of the foam pieces out of the upper grill.

Daox 09-28-2013 10:03 AM

In preparation for winter, I splurged and bought myself a ECT spoofer (coolant temp spoofer). It fakes out the coolant temp signal so you can get through the warmup stages more quickly and get to engine off operation faster. It will also allow me to use a bit more heat in the car this winter which should be nice.

More info on the install here:

Here are some images:

Daox 09-30-2013 02:12 PM

On the way to work this morning I definitely could tell a difference with the spoofer in place. I was able to engine off a fair amount earlier, if I had to guess I'd estimate 1/2 mile earlier than normal.. This comes in handy for me especially since my commute is only 7 miles. My warm up time eats up my mileage pretty badly. Anything to reduce warm up helps my mileage out.

Daox 11-12-2013 01:53 PM

The coolant hack is still working nicely. I definitely notice that I can engine off sooner. I'm also able to use my heat more aggressively now that its getting cold out which is really nice. This alone is worth it to me.

Daox 01-06-2014 02:49 PM

Now that its ridiculously cold out (-14F commute this morning), I'm still really liking the coolant hack. It definitely allows me to get heat sooner in the car, and it also allows me to use the heat more aggressively. When it is this cold, its really nice to be able to sit at a light with warm air blasting you in the face, and your engine isn't running. However, I will note that you can tell that the heater air doesn't get as warm. Still, warm is better than the engine on, or no warm air. So, I am quite happy. :thumbup:

Cobb 01-06-2014 06:10 PM

It almost sounds like there is a disconnect between getting warm air vs having warm coolant? The Insight heats the coolant and in turn gives you heat. When the engine stops, the warm fluid quits flowing. In your case getting the engine to cycle off faster thinking its warm up produces more warm air??? :eek:


Originally Posted by Daox (Post 392999)
What is a coolant spoofer you might ask? Well the Prius goes through 4 warm up stages before you can get it to turn off the engine every time like you'd like to do. Most of the stages are controlled by the coolant temperature. So, this little circuit tells the ECU that the engine is warmer than it really is to get you through the warmup process quicker. Also, if you have the heat turned on in the Prius, depending on the coolant temp, it will keep your engine running or not. So, the coolant temp spoofer basically allows for more engine off operation.

mechman600 01-06-2014 09:47 PM


Originally Posted by Cobb (Post 405970)
It almost sounds like there is a disconnect between getting warm air vs having warm coolant? The Insight heats the coolant and in turn gives you heat. When the engine stops, the warm fluid quits flowing. In your case getting the engine to cycle off faster thinking its warm up produces more warm air??? :eek:

Prius heaters are not that simple. I'm not sure what generation used what exactly, but battery pack powered heating elements and vacuum insulated coolant "thermoses" were part of it. I think Gen 3s use the pack powered A/C pump as a heat pump as well.

Cobb 01-06-2014 10:28 PM

I knew the EV Rav 4 used the ac in reverse as a heat pump, but didnt know they did that on the prius too. I knew it used a thermos to store 3/4 of the coolant for quicker start ups and it ran at start up to get the engine up to operating temp and also runs as needed to maintain temp along with a host of other factors.

I knew a few gen 2 prius owners who would complain of not being able to beat 43 mpg when winter came and they used the heater. I can see the heat effect mpg in my insight when it gets cold out on level surface I can crank it up and down temp wise without touching the blower speed and watch my mpg. :D

Daox 01-07-2014 08:59 AM

The 2nd gen Prius does have an electric resistance heater for the front windshield defroster and one for the front foot vent. They are operated under certain circumstances. The 2nd gen Prius also uses a coolant thermos that holds warm/hot coolant when you switch the car off and dumps it in when you turn it back on. The 3rd gen got rid of the thermos and instead uses an exhaust heat exchanger, so it can scavenge exhaust heat to warm the engine. The 3rd gen doesn't use the A/C in reverse for heating. There is no need to when there is free warm coolant to be had. There was a heat pump on the prototype PHEV Prius, but it was dropped for the production model.

There is no disconnect between having warm coolant and warm air. They're directly connected. If there isn't warm coolant there isn't warm air. :) By using the coolant hack it allows me to keep the engine off more often. The Prius uses an electric coolant pump so you can have heat while the engine is off. But, having the engine off doesn't warm things up as much, so things just stay cooler. Its not horrible by any means, but I thought I'd mention it because it is noticeable.

Cobb 01-07-2014 09:04 PM

So you are increasing auto stop so to speak and using what heat is available in the cooling system? The Insight you can easily run out of heat in auto stop and when at idle you can watch the temp noise dive to 130 degrees with the heater on. I tend to drive more aggressively in colder weather til the cold is worn off inside the car, so short trips just do not have good mpg.

Daox 01-08-2014 09:58 AM


Originally Posted by Cobb (Post 406114)
So you are increasing auto stop so to speak and using what heat is available in the cooling system?

Yep, thats basically it.

Cobb 01-09-2014 07:27 PM

Sounds like another +1 for the prius in cold climates. I have a vacant service road near where I live, so once I idle out of my community after having my block heater plugged in I have luke warm heat as my water is 132 degrees. I go for a 4700 rpm romp to 60 on this service road and after several seconds I can feel hot heat vs room temperature air come rushing out of the heater. :thumbup:

It seems once you get the water to 180 it holds its temperature better, but I think humidity pays more of a role in how auto stop behaves than anything else in the vehicle.

MetroMPG 01-12-2014 12:33 PM

Prius rear sway bar mod

I don't think you ever posted about your sway bar. That counts as an ecomod in my books (more confidence in keeping momentum through some turns).

Someone was just asking about g2 Prius suspension mods:

Cobb 01-12-2014 08:38 PM

Lets hear it Tim!!! Dont leave me hanging as to be the only fool to spend thousands in suspension parts and cross drilled slotted rotors for his hybrid. :eek:

Daox 01-13-2014 09:36 AM

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I had the same bar on my last Prius too (and my Matrix before that), thats probably why I didn't bother mentioning it. Its made by Progress for the 03-08 Corolla or Matrix. It just tightens up the rear end and gets rid of a good amount of tail wag which I really don't like.

Installation is easier than easy, jack the rear of the car up, remove two bolts, pull the old bar out, put the new bar in and put the bolts back in. An impact helps because they're not tiny bolts, but its not absolutely necessary.

Here is an image for the sway bar. Mine is grey though.

Cobb 01-13-2014 05:56 PM

Thats it? What about that little bar that crosses the exhaust near the center?

My Insight has the tanabe df210 lowering springs, progressive rear sway bar for an 09 fit, ultra racing rear strut bar, front strut bar, B pillar brace, under side b pillar brace and just recently new front sway bar links. 85 thousand miles and the passenger side is shot.

Daox 01-14-2014 12:07 PM

Nope, I don't need/want anymore than that. I'm not autocrossing the Prius, I just wanted it stabilized a bit more. Stiffer springs are IMO out of the question considering the roads here in Wisconsin get horrible every spring. I've had stiffer springs on a few cars and its just nice to have a normaler ride. I still run my tires at 50 psi.

RedDevil 01-14-2014 04:57 PM

50! That's way beyond the MTP on my winter tires. I'm already beyond that at 43 PSI, which cures about all my handling issues.
Thought it did not work out well as bad handling and side wind sensitivity were apparent the last month of so. Did a routine check and saw I was down to about 35 PSI all round ???
Upped it to 43 and problem gone. I'm convinced.

But I never felt the need of a sway bar. I have been driving cars hard, even did some amateur kart racing both indoor and outdoor. The Insight is the best cornering car I've ever owned, with no added suspension kits of any kind.
There is that corner leaving the highway, if the lights are green... I coast towards that, harvesting energy in the battery. Cars move up to my tail. Porsches, Audis, Priuses, you name it. I lose them all in that corner. I mean all. Nobody has yet kept up with me through that corner.
50 yards past on the straight they come blazing past to shed the humiliation or show their IQ or God knows what. Chill guys, just being green here ;)

Cobb 01-14-2014 06:02 PM

Yes, watching other cars get smaller in your mirrors is nice.

I dont think the roads here in America are designed or banked as they should be and you may have better roads in your country.

Daox 09-05-2014 10:02 AM

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Minor update, but it might be of interest to oil nerds out there. I just changed the oil on the Prius last night. I filled up with Valvoline's NextGen recycled synthetic 5W-30 oil. Yep, recycled oil. I've heard its junk from a couple people, so I decided to try it out. The plan is to do an oil analysis in about 5k miles.

Cobb 09-05-2014 05:24 PM

5w30 for your part of the country? I went with that weight as that was all I could find and my area typically hovers around the freezing point of water. Ive seen your part of the country get 32 past zero. :eek:

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