Pop N Wood Posted July 23, 2002 Share Posted July 23, 2002 Question for you auto professionals out there. I live in Maryland. For years, Maryland has used treadmills for smog checks so they can measure the tail pipe emissions under load. This year they replaced the treadmill test with an "OBD II check". If your car has an OBD II connection, they just connect a diagnostic tool instead of using the treadmill. Does anyone know what they are looking for? The paperwork says they read the error codes and if any are found they will give you a computer print out to take to your mechanic. They also say that if you had any work that required disconnecting the battery to make sure you drive the vehicle for 2 weeks before getting smogged. If all they are looking for is error codes, then couldn't I just reset the codes a block from the smog station? Are they really making it this easy or is there something in the OBD II output that actually measures emissions and/or states the last time the computer was reset? Quote Link to comment Share on other sites More sharing options...
Sumo Posted July 23, 2002 Share Posted July 23, 2002 Well here in the Dallas-Ft.Worth area they just started that OBD II test. What they are looking for is the same as before except with the OBD II they use your cars computer to see if all your emissions are within parameters. And they also check to see if there is an error code triggerred by an errant oxygen sensor or to see if you've been monkeying around in there. But what they dont tell you is that they raised the acceptable passing rate especially Nox levels. A lot of cars averageing from 94-97 are failing because of abnormally high Nox levels. (they treadmill 95 and below) So unless there is something mechanically wrong with your car what I usually do is just pour a bottle of RXP Drive it around for a week to blow all the stuff out. It also negates the oxygenated gas and completes the combustion and lowers emissions levels throughout. Check out their site. Although be aware that for a small bottle it treats 25 gallons but costs $6.95 i think. I've used this stuff, it's pretty good and i have no connection to the company, I just like their product. http://www.rxp.com/how.htm Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted July 23, 2002 Author Share Posted July 23, 2002 The thing is I think they dropped the sniffer test. All they do is read what ever the OBD II outputs and perform a pressure check on the gas cap (and I assume a visual check). So why wouldn't disconnecting the battery completely wipe the computer memory of any error conditions? Quote Link to comment Share on other sites More sharing options...
660Z Posted July 23, 2002 Share Posted July 23, 2002 i don`t think ECU`s work that way anymore.i need a scan tool to clear my 94 s-10...from what i understand OBDII tells everything from emissions to your everyday driving.im sure they made it as tamper proof as possable im not saying it can`t be done just won`t be easy...one things for sure it would take a computer wiz to figure it out....put away your wrench and bring out your laptop....the times they are a changing.....mark Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted July 23, 2002 Share Posted July 23, 2002 Yeah, that was my understanding as well about OBDII was that they're looking for anomolies and tweaking of the box, also as mentioned error codes. If the car's in good tune its actually easier, but it makes it harder to fudge I'd imagine because its all in black and white on paper. (or green or amber on screen ). Regards, Lone Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted July 23, 2002 Author Share Posted July 23, 2002 Did some research and found some very interesting links. Did you know OBD II cars (everything since 1996) have real time data logging of everything from A/F ratios, coolant temps, MAF and manifold pressures and even G forces? There is a data port next to the driver that, using a $250 tool, connects to a PC or palm pilot for real time displays and data logging. They say you can monitor how your engine performance varies with different grades of gas. This link has some good OBD background: http://hometown.aol.com/carleyware/library/us796obd.htm While this site is OBD specific: http://www.obdii.com/ But this site has quite a number of interesting articles and links http://hometown.aol.com/carleyware/index.html Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted July 24, 2002 Share Posted July 24, 2002 Yup, and if power is removed some codes clear, others don't. If they pull the codes and the ones they want aren't all filled in or at least 99% of them they will not accept the test. Swapping an ECU one from car to another won't work. The car must be run for a certain period of time on the ECU. On the brighter side the OBDII stuff is "standard" so what they're looking for is "known". There's a thread on the Supraforums board about this. Folks are debating creating a "box" to simulate an ECU and fool the test I'm betting that if this gets done it will be damned nice and illegal as all get out. One of the guys talking about helping is an emissions tech (lol). Now that you've researched OBDII try looking up some data on OBDIII and some of the flat out crazy things that have been proposed. Can you say remote shut off of a vehicle? Pretty sure that was tossed out but you get the idea - legislators have gotten involved Look at the BMW M3 thread I posted awhile back - BMW is using data from the OBDII ECU to DENY warranty claims. I canonly imagine what might be done with the ever more extensive OBDIII data (sigh). I have no idea where the OBDIII stuff stands now but I don't think it's anything good. One swap I've been considering, a cheap swap BTW, is a 2JZGTE drivetrain into a Lexus SC300. Better believe it'll be a pre-96 car if I do it!!! Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted July 24, 2002 Author Share Posted July 24, 2002 The first link I posted talked about OBD III. About how they can hook up a toll booth speed pass system or cell phone to automatically transmit the emissions status and VIN number to big brother whenever the check engine light comes on. One idea was to hook up a GPS receiver so not only will they your car tell them you need emissions work, it will tell them where you are. Quote Link to comment Share on other sites More sharing options...
Sumo Posted July 24, 2002 Share Posted July 24, 2002 You're correct by stating that OBD II started in 96. The reason they dont need the sniffer for 96 and above is because your own ecu monitors its own emissions. Kinda like sniffing your own butt But as far as i know if you disconnect the battery for as little as 20 minutes it will erase the error codes unless it has a mechanical failure or one of the sensors are out. The OBD I only lets you know if the sensors are dead or out of whack i think. Dont even get me started on the OBD III, buncha Nazi big brother black boxes if it ever goes in. Another feature on the III is it records the last 10 seconds of your driving for "Factory Use" only. Of course they didnt say that the insurance company could use that info against you like speed, steering angle, braking info. You know its kinda like the grocery cards, it gives you a discount but when you sue them for slipping in the store they'll pull up your purchase history and prove that you're a drunk, like the case in California. Power to the people (boy, that kinda went of topic) Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted July 24, 2002 Share Posted July 24, 2002 Supposedly the Corvettes can have data pulled in the event of an accident and obviously the M3s are storing data too. Read what I said above about pulling the battery - that's not an avoidance technique that will work. The emisions techon supraforums really had some good info about that... Quote Link to comment Share on other sites More sharing options...
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