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Strange Eccs Relay Behaviour

GTSBoy

By GTSBoy,
in Engines & Forced Induction

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GTSBoy Grand Master

GTSBoy

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Hiyas,

Recent transplant of RB25DET Neo into R32 started off running just fine, but after pulling out the ECU to swap R34 Nistune board for a Stagea one (unrelated problem was solved by changing from R34 image to Stagea image) the car started doing something odd. I was wondering if anyone has had the same drama and if the solution is easily dupicatable.

I don't think the change of Nistune board was the cause - I just think that pulling the ECU out from the kick panel area must have done a little tweak to the wiring around the various plugs and the ECCS relay. No violence or mishandling occurred, but obviously everything got moved around and tugged a little bit.

The symptoms:

  1. With the car cold (not necessarily stone cold, just not run recently), turn the key to on. No fuel pump prime, cannot connect to ECU with Consult. Do not hear the ECCS relay click on. Obviously no power to ECU. Can crank, but not start (not surprisingly).
  2. Turn key back to off, then back to on. Pump will prime, ECU powers up, can connect. Car will start.
  3. Turn engine off. Turn key back to on, no pump prime, no ECU again....but...
  4. If you didn't start the car at step 2 above, you can turn it off and on as many times as you like, and the ECCS relay will click on, power up the ECU, run the pump prime, every time.
  5. Every time the car is started in this condition though (cold), it will need to go through the key on-off-on routine to get it to go again though.
  6. When the car is warm, ie driven up the street and back, or any further distance, the car will always behave completely normally after you stop the engine. Pull up, switch off. Turn key to on, pump primes, ECU comes to life.
  7. Let it cool down for long enough, back to the on-off-on behaviour.

I'm sure the cold-warm behaviour difference has nothing to do with the temperature of the engine. I think it must just be some electrical warmth thing - where having been switched on and running it is warm enough to do what it is supposed to do the first time.

The ECCS relay has been swapped out and the behaviour remains the same.

Interesting side symptom - if, when the ignition is on but the ECCS relay is not working, no pump rpime, ECU dead, you pull the ECCS relay from it's socket and put it back in, the relay will kick in and everything works.

Someone suggested to me that it might be the ignition switch, but I am having trouble working out how the switch can give me the symptoms observed - especially the one triggered by pulling the relay out and putting it back.

Any thoughts? Is there a likley candidate of just a single earth wire or something similar that could be responsible?

cheers

Brad

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GTSBoy Grand Master

GTSBoy

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Posted

Not really possible. Conversion of an ECU to Nistune is not quickly reversible. I would try a plain jane ECU if I had one available. If my fishing for answers here and/or the direct troubleshooting work do not turn up an answer, I'll have to drag it around to Matt's place to see if we can swap the R34 board back in (assuming it still exists in the form I gave it back to him in) to conduct the nearest test to what you describe.

Thing is, I only just characterised the complete problem (as contained in the description in OP) on Sunday, then jumped on a plane to fly away for work. Time poor, internet rich just at the moment!

cheers

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