Hymotion and 52 MPH hack

The 52 MPH "Forced Stealth" hack has to do with setting an internal fault in the vehicle that causes the engine to completely terminate until the codes are cleared and the vehicle restarted. This can be accomplished several different ways technically speaking.

The problem is that you no longer have any ICE power in the vehicle until you power cycle your car. With a DC/DC Converter style system you run the risk of running out of battery power entirely on a road where it isn't safe to restart the vehicle (at higher speeds the DC/DC converter may not be able to keep up which could result in the vehicle stalling).

There is some discussion as to whether or not driving your vehicle above 41 MPH in this "Forced Stealth" mode damages the vehicle long term as MG1 is factory limited to 6,500 RPM which corresponds to 41 MPH in pure electric mode (since the gasoline engine isn't running, MG1 has to work a lot harder at higher speeds to keep up with MG2). It's technically rated up to 10,000 RPM (52 MPH) however Toyota generally has reasons for limits. The "Limp Home / Forced Stealth" mode was never intended to be used on a consistent basis by Toyota--some even think it was an unintended feature / bug to begin with.

Additionally, use of the hack sets diagnostic trouble codes in the vehicle that when cleared also end up clearing important learned information such as engine fuel calibration data that not only clear federally required emissions data (which can cause you to fail state emissions inspections) but also can lower mileage once you switch back to ICE due to the loss of calibration data (similar to what happens when your 12v battery begins to die).

I'm not going to tell you what to do since it's your car, but I would recommend that you avoid this hack as it can be dangerous both to you and your vehicle.

Andrew

 

@linuxpenguin; How many people have failed their emissions test due to the hack? I can't find a single instance of that on these boards (searched quite a bit with Google too). How many days does it take to rebuild that emissions data to pass the test if it is required?

@George S Bower: I'd be interested in a computer system which is able to raise the EV mode speed threshold from 52Km/h to even just 60-65Km/h. Most of the roads I drive on have a limit of 50 or 60Km/h, and having the engine "idle" is just annoying. If you find such a device or program, please be sure to post a link on this forum (this thread) so the rest of us can benefit.

I have been planning to put the 52mph hack into my Prius, and the worries of killing the transmission (since the 2004 lube pump only works when the engine runs) and failing the emissions tests have not put me off... yet. The current method does require cutting power to some ECU (usually fuel-pump/control) and an OBD2 scanner of some kind to clear the error code (mode $04).

 

You may be referring to the Hybrid Energy Manager from Ewert Energy Systems to allow electric only mode up to 70 MPH--this is not the same thing and does not set codes. Currently it's only available with Plugin Conversions (PICC) systems. Besides forced stealth mode, I'm not aware of any other such attempts.

@Snookum
I'm not aware of a set amount of time necessary to wait before the effects of forced stealth wear off--the key thing to understand is that by using it you clear the stored emissions data and if you take your car in for testing it will fail unless it has re-gathered enough information since its last use (lots of factors play in to how long that can take). You'd need a scantool to determine if the tests are actually complete. Lots of people fail the emissions test because they recently had their car serviced (the DMV around here tells you to wait a week or so after having your car serviced before getting it tested for emissions)--this would be basically the same thing.

Andrew

 

Thanks for the info linuxpenguin! I was a bit concerned because I have a recurring MIL come up (P1116 or P1150, both are coolant thermos sensor-short related) and have been just clearing the thing with reckless abandon. However, I was researching what the criteria are for the e-test in Ontario when I discovered that hybrids are exempt from the bi-annual test (and also everyone in Northern Ontario).

That Ewert thing is pretty damned slick... and it only comes with the PICC system! Damnit!

 

You probably want to look into that DTC as it could be a symptom of a larger problem (ie: better to fix a leak when its a leak before it turns into a hole).

Here in the US we have to get our cars tested bi-annually. Some states require actual emissions checking, others just poll the onboard computer systems via OBDII.

As for the Hybrid Energy Manager--it sure is pretty slick (I mean, I think it's pretty slick and fun to drive anyway). You could contact Hymotion and see if they want to follow up with Ewert Energy Systems about licensing the technology for their system I suppose. I don't know if Hymotion would be interested or not.

Andrew

 

If there are instructions for the 52 MPH hack please post a link to them.

 

hobbit's page: No Squirt
His method was the one I was going to try (kill the fuel-pump power), but I was just going to throw a switch on the dash.