Automobile On Board Computers

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Mr. Skinny
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Joined: Sun Jun 06, 2004 2:21 pm

Automobile On Board Computers

Post by Mr. Skinny »

I went to have my state-required environmental check on my car today.

They didn't put my car on the dynamometer. They didn't shove a probe in the tailpipe to measure the exhaust. They didn't put a big fan in front of the radiator to cool the engine.

Nope, they crawled into the interior of my car with a cable and did "something". Next thing I know, I'm getting my print-out saying the car "passed".

I went back to work and found out these computers store all sorts of information on your engine performance, maximum speed, contain an accelerometer, etc.

Would love to know more about what they can store.

Maybe I've been in the dark ages since I just bought a new car 2 years ago (after driving a 1984 model), but couldn't there be privacy and legal issues here? Are they using this data as evidence in liability proceedings?

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Luke T.
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Post by Luke T. »

They do that in my state as well. They plug into something under the dashboard. I don't know how that tells them if my car is a polluter, although there is an O2 sensor in cars now, isn't there?

I think they only do the tailpipe thing if your car is a certain age.
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Mr. Skinny
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Post by Mr. Skinny »

Luke T. wrote:They do that in my state as well. They plug into something under the dashboard. I don't know how that tells them if my car is a polluter, although there is an O2 sensor in cars now, isn't there?

I think they only do the tailpipe thing if your car is a certain age.
There is an O2 sensor, plus several other sensors for engine performance that could be stored. Not sure, but they could also put a sensor downstream of the catalytic converter, I suppose.

I quit working on my own cars about 5 years before I got rid of my '84, so I'm really kinda clueless about it. Thought someone here might be a mechanic.

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Zombified
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Post by Zombified »

The federal government has been requiring "on-board diagnostic" computers on cars produced since I think 1998, or thereabouts. There are certain standard emissions measurements that are mandated. You can buy OBD interfaces for your laptop and software that knows about the standard stuff.

Most manufacturers use the same interface for other stuff, which adds proprietary stuff to the protocol. The manufacturer-specific software is usually pretty expensive and sold to authorized mechanics.

These days, when your 'check engine' light comes on, its usually the OBD complaining about something emissions-related.

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Bearguin
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Post by Bearguin »

There have been computers on cars since the late 80's. I have (it's for sale if you want it) a 94 GMC 3/4 ton pickup and bought a ful scantool for it. I can see what my O2 readings are, temperature, speed, rpm, what my tranny is doing and lots of stuff.

In 1996, they went to a fancier computer (ODBII vs ODBI) that will store data for later recall etc. Newer truck like mine had 4 O2 sensors so they can tell if a cat has been gutted or if other modifications have been made and they can tell if your vehicle is within spec or not.

Now, I just bought a 94 Diesel (hence I'm, sellling my other one) and one of the first things I've found out is the computer that controls the main fuel injection pump is sitting on top of the motor where it overheats and fries the pump. So I have to spend ~$400 to relocate the computer to save spending ~$2,500 on a new pump. Frigging design flaws.

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bug_girl
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Post by bug_girl »

Last weekend i had a Prius for my rental car for a road trip!
Very cool, with a touchscreen display that controlled everything in the car. audio, temp, multiple displays of energy consumption, powertrain....eventually i turned the damn thing off.
way cool car, but so much technology makes me nervous. i long for the days of my 77 honda civic with the manual choke. 8)
(and yes, i am seriously considering a used 2002 insight. your point? :lol: )