Engine Drivetrain 1st Gen Cooper S P0270 code

Discussion in 'Tuning and Performance' started by UKXPAT, Jun 19, 2010.

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  1. UKXPAT

    UKXPAT New Member

    Nov 12, 2009
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    Has anyone experienced a P0270 code? My manual says it's 'Cylnder 4 injector circuit low'. Engine appears to be running on all 4 cylinders still. I haven't investigated in detail yet, but was wondering if anyone had seen this before and had any hints.
     
  2. Nathan

    Nathan Founder

    Mar 30, 2009
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    The causes of the code could be any of the following:

    * Bad injector. This is usually the cause of this code but doesn't rule out the possibility of one of the other causes
    * Open in the wiring to the injector
    * Short in the wiring to the injector
    * Bad ECU

    Possible Solutions

    1. First, using a digital volt ohm meter check the resistance of the injector. If it isn't within specs, then replace the injector.
    2. Check for voltage at the fuel injector connector. It should have 10 volts or more.
    3. Visually check the connector for damage or broken wires.
    4. Visually check the injector for damage.
    5. If you have access to an injector tester, activate the injector and see if it operates. If the injector operates, then you likely have either an open in the wiring, or a blocked injector. If you do not have access to a tester, swap the injector with another one and see if the code changes. If the code changes, then change the injector.
    6. At the ECU, remove the driver wire from the ECU connector and Ground the wire. (Make sure you have the correct wire. If you're not sure, do not attempt) The injector should activate
    7. Replace the injector
     
  3. UKXPAT

    UKXPAT New Member

    Nov 12, 2009
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    Thanks for all the great pointers. I will check these out tomorrow as I am swapping out my IC. What I find interesting is the engine seems to be running OK, so fuel must be getting into that cylinder at least. Of course swapping out the injector will take a bit longer as they are specials from RMW.
     
  4. Nathan

    Nathan Founder

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    Swap injector positions, move 4 to 2 and see if code moves.
     
  5. UKXPAT

    UKXPAT New Member

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    Just swap the connectors over? Does the engine have to be running, or just the ignition turned on to check? Also, do the injectors actually have to be in the fuel rail and engine to check the circuit? I do still have my original injectors, so could I plug one of those into the faulty location's connector and turn the ignition on to check?
     
  6. Nathan

    Nathan Founder

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    I mean pull the injector out of #4 and place it in #2, take #2 and put it in #4. Reassemble all, clear codes and start car. See if code comes back or moves. If it moves then it's an injector issue, if it comes back at # 4 then it's an electrical issue. If perchance it goes away completely then chalk it up to a bad connection that was reseated duri9ng the swap.
     
  7. UKXPAT

    UKXPAT New Member

    Nov 12, 2009
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    Well that was a bit of a nightmare ride! Saturday, I cleared my 270 code with my scan gauge, and everything was fine again. Sunday I did my IC changeover. While in there I decided to check the wiring around the #4 injector. Made sure there were no kinks in the wires, and put everything back together. Fired up the car, and now had definite misfire on #4. Now I had 270 and 304 codes. Started to pull my hair out, jumped and screamed a little, then calmed back down and stripped everything down again.
    Due to the larger injectors fitted, there is an adapter cable between each injector and the OEM harness. I took the one from #4 out and checked it over. Made sure everything appeared to be seated right in the connectors, no split cables or anything, and put it all back together again. Fired up the engine and it is back to running on all four cylinders. Phew! Cleared the codes again and let it run for a while.
    Obviously there is a possible intermittent lose connection in there which I will have to keep an eye on and maybe prepare to replace the adapter cable at some point in the future. At least I know what's causing the issue if it happens again, so good learnings.
     

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