Supercharged Camira..

Craig and Adam\’s attempt at adding an SC12 to a JE Camira wagon

2 Bar Map Sensor

Posted by superchargedcamira on October 2, 2006

Spent some time the other night creating the ecu bin for the 2 bar map sensor. I went and burnt an initial test rom so i could give it a try that weekend. First problem i ran into was that the connector for the standard map sensor didnt fit into the 2 bar sensor we had purchased. The plug looked correct however it turns out there are 2 small plastic guidance bits which are different on the two sensors. Im guessing thats just to stop someone accidently putting the wrong sensor in.. either way, it was nothing that a hobby knife couldnt fix. With a little bit of handywork that plug was fitting in quite nicely.

So with the sensor connected and the new rom in, it was time to see if she’d start. I turned over the engine and she started up just fine.. for about 3 seconds and then she stalled. I tried a few more times with the same result. I had the ALDL running and noticed it had triggered a malfunction flag for the O2 sensor.. I went and checked all the connections and they seemed fine, so i switched back to the 1 bar map and original rom and the car ran fine. I cleared the error code and tried again with the 2 bar.. same result, but no error code occured this time, so im not sure what the cause of that was.

I wasnt really sure what was wrong at this point, so i did some comparisons of the map readings on the ALDL from both sensors. The standard sensor gave an idle map reading of around 40, and the 2 bar gave an idle map reading of around 20 which is what i expected. Next i went and reviewed the rom settings and noticed that the idle spark advance for 20 map was really high, 29.88 degrees. The 30-70 map advance was 9.84. Now since i knew that with the normal map it was reading ~40, it would have been using 9.84 degrees, but the 2 bar was reading around 20, so it would have been using the 29.88 degree advance. I figured this was the problem, so i modified it to be 9.84 and burnt a new rom. When i tried it with the new rom, it idled very roughly then stalled.. not much better than before. So at the moment im a little stuck as to what the problem is.. im assuming it would need to either be air/fuel or spark advance, or maybe a combination of both.

Im assuming that when you start the car it uses the F1 IDLE (Idle spark advance) table, and either the F56 Cold Engine A/F and/or F57B Idle A/F tables? Can anyone confirm this? Any thoughts or ideas are more than welcome.


7 Responses to “2 Bar Map Sensor”

  1. I might be way off here but I may as well mention it just in case.

    I’m assuming that the map sensor’s indicates it’s output by modifying the voltage based on the current pressure within the manifold? Your in a reasonably old car, so the voltage range would probably be 0 – 12 volts on the signal line.

    With the 1bar map sensor, 0v would equal 0bar, and 12v would equal 1bar. With the 2bar map sensor, 0v would equal 0bar and 12v would equal 2bar.

    So, if the voltage was currently 6v on the signal line, on the 1bar map sensor that would indicate 0.5bar – and on the 2bar map sensor that would equal 1bar.

    So, would you not have to modify the values the ECU should be expecting from the MAP sensor?

  2. Err, I mean, shouldn’t you have to halve the values expected by the ECU.

  3. Craig Jorgensen said

    Yep thats what the rom we created was for. We went through and modified all the tables that used MAP to handle the halved resolution that we now have with the 2 bar sensor. FYI the map sensor outputs 0-5 volts.

  4. Matt said

    if you want i can take a look at the bin file when i have a chance and see if i can be of any assistance.


  5. Cheers Matt, that would cool if you could.. we will still play around when we can but it would be good to have your opinion. Can you send me an email if possible? ive lost your email address – email problems. Cheers..

  6. Matt said

  7. Scott said

    Hey Guys Any chance you could email me on would be cool to have your email address as I too am working on a Project JE In Perth.

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