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General => General Discussion for Everybody => Topic started by: Morfy on January 11, 2016, 11:18:00 PM

Title: Vehicle Went Into "Limp Home Mode" (LHM) !
Post by: Morfy on January 11, 2016, 11:18:00 PM
Quick story, I was driving a company vehicle on Friday, and there was some engine issues, where the Check Engine Light came on, and then something strange happened:


The vehicle was limit to no more than 2500RPM (mind you, I was on the highway when this happened).


Mechanic told me the vehicle went into "Limp Home Mode" (LHM), or a protective state that allows one to travel, just at a greatly decreased amount of power.


I never heard of this before, and it can be from something as stupid as an O2 sensor, etc.....


Have any of you every dealt with LHM with a car?
Title: Re: Vehicle Went Into "Limp Home Mode" (LHM) !
Post by: Reezy on January 22, 2016, 09:19:16 PM
had it happen on my older bmw when the automatic transmission was really crapping out.

although i think it can happen with overheating too? basicly to prevent more damage. i am not sure about the O2 sensor but maybe if its too lean or somthing?

what kind of car? i mean if its company car they are going to fix it right?

Title: Re: Vehicle Went Into "Limp Home Mode" (LHM) !
Post by: Zoops on January 22, 2016, 09:23:42 PM
Yeah, I had this happen with my 2000 Volvo V70 wagon once. Transmission problem. Limped it over to the dealership and had it fixed under warranty.

I hadn't ever heard of it before either, until then.
Title: Re: Vehicle Went Into "Limp Home Mode" (LHM) !
Post by: Morfy on January 22, 2016, 09:36:59 PM
Hey thanks guys: It was a Mercedes-Benz Sprinter (the boxy van thang):

(https://forum.drugs-and-users.org/proxy.php?request=http%3A%2F%2Fimages.thecarconnection.com%2Fsml%2F2015-mercedes-benz-sprinter-passenger-vans-rwd-2500-170-angular-front-exterior-view_100497585_s.jpg&hash=a270cd7a0c38a0c15e4bad23f387db59a51d8bde)yeah--MorFy's riding in S T Y L E.......




And I guess the LHM is a reasonable solution--and there are various levels, depending on the detected problems, and the computer's programmed response.
Title: Re: Vehicle Went Into "Limp Home Mode" (LHM) !
Post by: DeadCat on January 22, 2016, 11:06:07 PM
Don't be fooled. This is a kill switch that the state has installed in all new cars for at least 10 years now. You can run, but you can't run far. Sometimes they malfunctin and sometimes cops activate them when they see a car that "fits a description."


They work by sending a signal to the car's computer retarding performance.


Or maybe I'm making this shit up.
Title: Re: Vehicle Went Into "Limp Home Mode" (LHM) !
Post by: Morfy on January 22, 2016, 11:45:58 PM
You Know Dead-C:


 That would be a believable conspiracy--we only need to see a few video clips of this happening.


You've heard that someone tapped into the Infrared signal that Fire Trucks used to change traffic lights--so the truck gets greenlights all the way to the fire? 


This smart guy was finally tracked down, and fined severely. (actually, he became a felon!--bad monkey, you not supposed to figger dat out!):
http://www.caranddriver.com/columns/how-to-become-a-felon-without-really-trying



If there was a car kill switch, or an "easy catch mode" someone would likely tap into that, and then start fucking with people.




I might want to be THAT guy!! :-*
Title: Re: Vehicle Went Into "Limp Home Mode" (LHM) !
Post by: Opus on January 23, 2016, 12:29:14 AM
Sometimes you can clear the (limp) code by just re-setting the ecu -- frequently can be done by just disconnecting the ground cable for a few minutes. That's probably much more likely to work with OBD2 than OBD3+ tho, but maybe only by adding in small jumper.

Probably gonna need a tty shell to go much further.

Here's a couple interesting vids on car haxin' I came across recently.

Not mentioned much: but GM's OnStar is remote r00t waiting to happen, you can quote me on that.





Title: Re: Vehicle Went Into "Limp Home Mode" (LHM) !
Post by: Guts on January 23, 2016, 07:20:31 AM
My BMW does it. Its M73 V12 is essentially just 2 M20 inline 6s joined at the hip. So if there is something wrong with one bank of cylinders, it'll shut that side off and just run on the other so you can literally limp home. Some Mercedes V12s do this at cruising speeds to save gas.
Title: Re: Vehicle Went Into "Limp Home Mode" (LHM) !
Post by: Opus on January 24, 2016, 06:08:05 PM
Don' be fooled. This is a kill switch that the statehas installed in all new cars foratleast 10 years now. You an run, but you can't run far. Sometimes they malfunctin and sometimes cops activate themwhn theyse a car that "fitsaescription.


They work by sending a signal to the car's computr retarding performance.


Or maybey I'm making this shit up.

General Motor's "OnStar" has this (or v. close to it) capability.

Personally I'm a little concerned about Tesla. Really interesting cars, but so are Old Lotuses and electric bicycles.

I'm not sure I need an $80k car that will likely soon regularly start pushing out patches faster than you can say "Ruhroh another zero day. You gotta drive the Volvo again today Honey, sorry 'bout that."

(I can't say I wouldn't rock a 1G Tesla tho, flat gorgeous those cars, dead silent too all you can hear is the fan cooling the batteries)

Title: Re: Vehicle Went Into "Limp Home Mode" (LHM) !
Post by: Guts on January 24, 2016, 08:02:06 PM
What is a 1G Tesla? Google is only finding lateral acceleration stats for the p85... are you talking about the lotus bodied roadster? I saw a YouTube video of a 3 series that was switched to electric power and had some crazy amount of torque.... it was weird, it made like a turbo noise when accelerating. It didn't souND anywhere as good as a gas engine but it did have a sound.
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