ODBII Compliant?

[milooney]

I always thought our cars were OBDII compliant, I have had autozone read CEL's for me using their sensor. I guess I'm confused now because I was thinking about ordering an "Ultra Gauge" because I had seen good things about them in other forums. Basically it gives you data about your car via the OBDII port, but their site says that they are not supported on Subarus older than 1999, because they are not OBDII compliant. Their website is Ultra-Gauge.com. Does anyone have any insight as to why these things might not work with our cars?

[daddywagon]

thats funny the scanners at autozone work fine on mine.

[milooney]

That's what I'm saying. I have never had a problem with them reading my codes... nor have I had problems with the reader my dad just bought. I ordered one anyways, because it looks like they tested a 95 [which was technically before OBDII was required] and decided based on that that all subarus before 1999 were not supported? They didn't say what model they tested either. If I get it and it doesn't work I will just return it, they have a 90 day policy.

[98quiksilvergt]

Is it a scanner only? If it's anything like the kiwi wifi it didn't work with my 98. All it would do was check codes. That's made to work with iPhone. That's only 1/4 of what it's capable of.

[subikid90]

Its because our ECU's are very restrictive. We cant write to them and can only read a few sensors and code and thats it. I have Torque on my android phone with the ebay bluetooth reader and I can only see my coolant temp and engine load.

[Platinum_Racing]

This is true.

 

OBDII Compliant doesn't require that auto manufacturers build cars with the capability to write data onto the ECU. It only requires that the CAN bus and all codes are standardized to a point where a single generic tool can be used to read any vehicle.

 

Older OBDII compliant cars are simpler. The simpler the systems, the less they are capable of. To keep the engine running the on-board computer must do so many things and monitor many systems simultaneously. The way the computers in OBDII cars are created allows certain functions to have a higher priority over other functions. Older OBDII systems are less powerful than newer systems. Therefore they cannot process many requests at once. For example; if you try and poll the ECU to give you information on the position of the IAC solenoid while its trying to operate dozens of sensors, your request for the IAC solenoid position will be assigned a "Recessive" priority status and will be put on hold while the ECU manages critical tasks that keep the engine functioning. Systems related to keeping the engine running are assigned "Dominant" priority status. These "Dominant" systems include MAF values, TPS values, primary O2 (Before Cat) values, cam position values, and crank position values. "Recessive" systems include knock sensor values, secondary O2 (After Cat) values, and coolant temp values. The more important the task, the sooner the ECU will get to processing that task. Anything you ask the computer for through the OBDII bus will likely be assigned a "Recessive" status, meaning it is not of high importance. Once your OBDII tool is assigned a "Recessive" status it will wait 6 clock cycles before attempting to contact the computer again. Each time it tries to contact the computer its given another "Recessive" status and continues to wait.

 

 

Newer cars with more complex computer systems have a CAN bus that operates with a higher bit-width. That means it can transmit/receive more information at once. The frequency of their processors is also higher, allowing the computer to process more information at once. Your attempt to retrieve information related to the IAC solenoid is more likely to be fulfilled because the ECU actually has enough time and processing power to get to your request AND keep the engine running all at the same time. When your car was built these OBDII devices were a mere pipe dream. The only time you ever needed to send information to the ECU (Or retrieve specific information) was if you were going to re-flash the onboard EPROM. Flashing the EPROM (Or "Erasable Programmable Read-Only Memory") is something usually only done at the dealership or an experienced aftermarket tuner with thousands of dollars worth of equipment as there is a high risk of damaging the on-board computer should things go wrong during a re-flash.

[milooney]

Well, I already ordered it. I will see how it works and if I don't like it I have a friend who said he would buy it off me for what I paid. Hopefully it works [although it doesn't sound like it will], and if it doesn't I'm not out anything. Thanks for the responses guys!

[Bassnectar]

I got a tactrix 2.0 cable. which on newer subarus you can view all the sensors info with guages and stuff like that you can actually re-flash your own ecu...

 

 

course it was to good to be true for the older legacies i ended up taking a 40$ hit and selling it to someone with a bug eye

[milooney]

Update:

 

I got the gauge, it DOES NOT work, as was expected. It is however pretty sweet when used in other cars.