SiriusProjects Posted April 10, 2016 Share Posted April 10, 2016 Hi Guys, Recently I had to use my ODB2 connector and Datascan software to check for error codes and while doing so, I started thinking about something I queried a while ago but never really got to the bottom of. The software is great and I especially like the data display which shows all the dials and what readings they are returning. However, the one thing I've never really mastered is being able to interpret what the information being displayed is actually telling me. It looks really cool, but I want to be able to understand the data itself. I want to be able to look at a reading and think, that's a bit high or that's a bit low. But I've got no reference. I don't know what the acceptable ranges/tolerances are supposed to be for each component. I'm not going to mess with any settings. I'll leave that to an expert. I just want to be able to read and understand the information displayed. Thanks. Quote Link to comment Share on other sites More sharing options...
Jetpilot Posted April 11, 2016 Share Posted April 11, 2016 Specifically what data are you talking about? If anything was out to the point of concern you would probably know about it anyway as the car would be running rough. Quote Link to comment Share on other sites More sharing options...
SiriusProjects Posted April 11, 2016 Author Share Posted April 11, 2016 Hi Jetpilot. I haven't got my own data to hand, but I did find a screenshot online of the dials and have a couple of examples below. Air Flow Dial Reading - 2.2 A/F Base - 100 Injector Reading - 12 Firstly I don't know what measure is being used for these values and I don't know what the values themselves mean. They are probably all okay, but I want to be able to understand what they are telling me and what the tolerances are. I mean say for instance the Air Flow Dial Reading should be within a range of 2.0 to 2.4 for a Nissan 350z and my zed came back with a reading of 2.5. It's only just over, but at the moment I have no idea what the range is and that 2.5 is quite possibly outside that acceptable range. My usual mechanic hooked my zed up to his diagnostic equipment last week as I had a Throttle Position error come up. He looked at the readings and said that the voltage of the sensor is reading okay. But how does he know that? Where did he get that knowledge from. He primarily deals with Fiats and Alfas, yet he knew that the reading of my Nissan was okay. I'm not a mechanic and I never attempt any work on my zed myself as I'm not confident in my own abilities. I've worked in IT for 20 years and data is my thing and I just want to be able understand this data. Thanks. Quote Link to comment Share on other sites More sharing options...
blazemaguire Posted April 12, 2016 Share Posted April 12, 2016 I think you'll struggle to translate. The readings are probably just ratios that mean something to a computer program only, I.e the ECU knows to adjust it's outputs of air flow for instance to stay between a certain ratio, say 1.3 to 2.4. This will have a value that the original Nissan engineers could translate, but you're just seeing the raw data the cars sensors create.... I.e you're just seeing the numbers the computer gets, rather than something that's useful. The important thing is it stays within the range / ratios for each parameter, rather than what it translates. (Control loops..). I teach this sort of stuff for a living. Quote Link to comment Share on other sites More sharing options...
Jetpilot Posted April 12, 2016 Share Posted April 12, 2016 I guess if you understand data it will float your boat, but cars are a mechanical thing, the readings are just varying signals from sensors, you will soon know if something isnt within range as the car will run rough/throw a cel, of course some things are worth monitoring, but you have them anyway, fluid temps and pressures, battery voltage etc, forgive me for saying, but sounds like you are in danger of over analysing. Quote Link to comment Share on other sites More sharing options...
SiriusProjects Posted April 12, 2016 Author Share Posted April 12, 2016 I get what your saying Jetpilot. It's not just that though. The thing is, whenever something goes wrong with my car, I immediately take it to the garage and get them to fix it and obviously if that involves running diagnostics, that's something I get charge for in addition to any work needed. I've always been more into styling than performance and the actual mechanics of cars, but I'm getting to a point where I want to increase my knowledge of that side of things. If I can save myself some money by pinpointing a fault and maybe even fixing it myself, then I could start saving myself a lot of money. I'm not looking to become a fully experienced mechanic, I would just like to gain enough knowledge to be in a position where I can be more informed about any problems that do occur. Quote Link to comment Share on other sites More sharing options...
BulletMagnet Posted April 12, 2016 Share Posted April 12, 2016 probably best to ask one of the tuners on here, like Abbey or Horsham what these values mean and hopefully you will be enlightened Quote Link to comment Share on other sites More sharing options...
Jetpilot Posted April 12, 2016 Share Posted April 12, 2016 Does the datascan give you fault codes? Quote Link to comment Share on other sites More sharing options...
SiriusProjects Posted April 12, 2016 Author Share Posted April 12, 2016 I've recently upgraded to the latest version of the datascan software and yes it does give the fault codes. That's how I was able to determine that the recent issue I had with my zed going into Limp Mode was concerning the Throttle Position Sensor. I had my zed uprevved at Horsham Developments and I was fascinated by the process of plugging it into a laptop and changing the characteristics of different components in such a way that you can see some noticeable gains. My zed is the first car I've ever owned with that ability. All my previous cars were a lot older and didn't have that technology. I'm a bit of a late starter when it comes to cars and I'm learning all the time, picking up bits and pieces here and there and it's something I want to get into more. I would like to learn more about engine tuning, about what settings there are and how to adjust them, etc. I don't know whether it's something I'd get into seriously, but it is something I'd certainly like to learn more about and gain a better understanding of. Quote Link to comment Share on other sites More sharing options...
andy10v Posted April 12, 2016 Share Posted April 12, 2016 The MAF signal is 0-5v, gm/s could be calculated from that if you knew the offset, it will be non linear. A couple of bits of info from other forums Output voltage at idle 1.1 - 1.5*V Mass air flow (Using CONSULT-II or GST) 2.0 - 6.0 g.m/sec at idle* 7.0 - 20.0 g.m/sec at 2,500 rpm* *: Engine is warmed up to normal operating temperature and running under no-load. you should see about 1 volt from MAF while in idle and idle airflow is about 2.0 gm/sec. The spec says 1.1v - 1.5v idle voltage from MAF = 2.0 - 6.0 gm/sec Would you want to tune the engine through uprev or learn to map the ecu yourself? Quote Link to comment Share on other sites More sharing options...
SiriusProjects Posted April 13, 2016 Author Share Posted April 13, 2016 Hi andy10v, I think it will be a while before I would attempt to tune the engine myself. I'd first want to develop a much better understanding of what's involved, how to read and interpret the data and how to change the various settings to achieve different results. Just really need a place to start. Quote Link to comment Share on other sites More sharing options...
andy10v Posted April 13, 2016 Share Posted April 13, 2016 If you want to play with the ECU software you can dump the bin, convert to hex, then you can have a look. These threads might provide some starting points http://home.exetel.c...13b2f4c0a16150d http://www.romraider...&t=9888&start=0 http://forums.openec...php?f=15&t=2639 To know everything I think you would dissasemble in ida pro Quote Link to comment Share on other sites More sharing options...
SiriusProjects Posted April 13, 2016 Author Share Posted April 13, 2016 Thanks andy10v, I will have a look at the links you provided. Quote Link to comment Share on other sites More sharing options...
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