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ECU Error Code 3 and MAP Sensor

Discussion in 'ECU's, Electronics, and Tuning' started by infotechplus, Mar 12, 2005.

  1. infotechplus

    infotechplus Junior Member

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    Hi,

    I have replaced my SOHC VTEC engine (D16Y1/P28) with a JDM B16A/P30 (Serial # 5###). The ECU is throwing a CEL of 3 which indicates a MAP sensor electrical fault.

    Where is the MAP sensor? It is not on the firewall (the D16Y1 had it mounted on the Throttle Body) and it is not on the TB. So, how do I fix this problem? Also, I am using the original harness from the ECU to the strut towers, and then the B16A harness from there. There is no plug connection for the MAP sensor.

    It is also throwing a 14 which is the EACV, which I have replaced but to no effect.

    Main symptom is the car idles at between 1500 and 2000 RPM, resulting in very poor fuel economy (300KM on a 45L tank of ULP98 octane).

    I understand I have to also send a wire from the Knock Sensor to the ECU to enable the VTEC. What is the best way to do this? I tried inserting a pin in the plug but it didn't quite fit. Should I trace the KS wire through the harness and see where it ends up, and connect to there?)

    My car is an Australian-delivered EH9 ('92 - '95 Civic sedan, designated VTi here in Australia).

    PS. I am running a modified P30 with ROM socket but the ECU is switched to "standard" mode.

    Peter <_<
     
  2. reckedracing

    reckedracing TTIWWOP VIP

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    i think the IAC and MAP plugs are very similar and can be accidently switched...

    i also think you need to add a firewall mounted MAP sensor to your civic firewall...

    as to why there is only one plug... i have no idea on that one...
    can you plug your EACV plug into the map sensor that was on the D series throttle body?

    from our refrence section here
     
  3. infotechplus

    infotechplus Junior Member

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    Thanks for your reply. I don't see how I can accidentally switch a plug that's not there. The car runs fine, just idles too high.

    Logic tells me that I am getting a CEL #3 (electrical MAP sensor) because the ECU is looking for a MAP sensor but isn't finding it. So where is the MAP sensor? Further to this, I saw two more B16As at the shop where I purchased mine - one had a MAP sensor on the TB (B16A with Serial # beginning with 5) and another one was the same as mine - no sensor but I didn't check the wiring harness to see if there was a plug. I think I'll do this tomorrow.

    Adding one sounds fine but what do I plug into it?

    I'll check the MAP on the D16 but what effect does plugging an EACV connection into a MAP sensor have on the ECU or car's idle?

    Thanks again,
     
  4. infotechplus

    infotechplus Junior Member

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    OK. I connected the knock sensor directly to the ECU through the firewall. This alleviated the Code 3 (and the Code 14) ther P30 ECU was generated. Idle has dropped to about 1300 - 1500. <_<

    I reset the ECU and shorted the test circuit and now get a code 20. :(

    I will play with the idle and report back.

    Perhaps this indicates that the P30 ECU KS circuit also handles the Map Sensor's job. Can anyone confirm this?

    The car is running a lot smoother, although I'm still having trouble detecting when the VTEC cuts in. What is the factory cutover point? :)

    Thanks
     
  5. pissedoffsol

    pissedoffsol RETIRED

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    p30 transition = 5800

    the knock has nothing to do with the map sensor.

    do you have a plug haningn out in the back of your motor doing nothing?

    yes, some are fire wall mounted- and others are TB mounted.

    it doesn't matter how its set up... just run a vac source to it if you can't put it on your TB and mount it somewhere, and plug it in. map sensor is now working.
     
  6. infotechplus

    infotechplus Junior Member

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    Thanks for the cut over point.

    There are no left over plugs on the harness and nowhere to plug into. The MAP sensor is neither on the firewall or on the TB.

    Peter
     
  7. reckedracing

    reckedracing TTIWWOP VIP

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    hmmm, let me see if i can help you here...

    your car = TB based MAP sensor...

    the car your B16 came from = MAP sensor on the firewall...

    so the motor doesn;t have it, and the firewall doesn;t have it, so you need to put it in there...


    so you can try and use the D16 one, or get a firewall one...
    those are your choices...
    and if you don't have an extra plug them something tells me the harness you are using is hacked...
    look for any cut or bare wires...
     
  8. infotechplus

    infotechplus Junior Member

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    All sounds logical to me. I was thinking along the same lines.

    But how do you explain me not getting a CEL Code #3 anymore since I connected the KS to the ECU? :blink:

    Thanks for your help to this point,
     
  9. reckedracing

    reckedracing TTIWWOP VIP

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    lmao, i have no idea dude, how long did you leave it running?

    a MAP sensor is one of those things that you usually see the result of it right away... like your car just running like complete shit...
     
  10. reckedracing

    reckedracing TTIWWOP VIP

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    you still have the code #20? you know what 20 is?

    where did you get your motor from? are you sure someone didn't lop off your map sensor plug off the harness for some reason?

    i would check the colors going to the IAC, make sure they aren;t for the map, but either way one of your plugs is missing...
    it might be the map plug, and you need a map, and then you need to add the IAC plug...

    what happens when you unplug your IAC?

    take your MAP off the D series throttle body... then ghetto fab it and connect it to a vacuum source... now plug your one magical plug into that... see if your codes change at all...
     
  11. infotechplus

    infotechplus Junior Member

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    Code 20 is the Electrical Load Detector, located under the fuse box on JDM B16As.

    I have the problem sorted now, thanks to various forums but especially the guys over at OzHonda.com.au

    The JDM B16a comes in two flavours. One has the Map Sensor mounted on the Throttle Body, like my old SOHC D16Y1; the other has the MS mounted on the firewall. The harness of the JDM B16A is split between the engine harness and a firewall harness.

    The car that donated my B16A was an EG6 SiR which uses a firewall mounted MS and loom separate to the main loom. (it also had an ABS harness which I didn't use). That is why I can't find that last MS plug. So I have to go back to the engine supplier and get either a MS to mount on the firewall or another throttle body with integrated MS. Then connect the vacuum lines and everything should work.

    I can then run the three wires required (D17 - white, D19 - Yellow/Red, and D21 - green/white) from the ECU to the MS directly or get a plug from the wreckers and wire it (best approach).

    The Code 20 is solved by substituting local delivery fuse box for JDM B16A fusebox. Or I can simply turn off that sensor on my chipped P30 ECU.

    I will hopefully solve the MS problem first and then see what happens.

    At least, now, there is light at the end of the tunnel and I can stop refilling my fuel tank every 300 Kms!!

    And activate the VTEC ............

    Cheers,
     
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