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Air(smog) pump relay clicking

Discussion in '348/355' started by F129b, Dec 5, 2020.

  1. F129b

    F129b Formula Junior

    Feb 6, 2004
    478
    oc, calif.
    Full Name:
    Robert
    The relay I bought is correct. Image Unavailable, Please Login
    Thank you for verifying the particular spec. Next I will try it in case the other 2 have been incorrect..Ground #14 pin if this relay brings same issue.


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  3. F129b

    F129b Formula Junior

    Feb 6, 2004
    478
    oc, calif.
    Full Name:
    Robert
    I earthed the #14 socket today and the pump runs without chatter from the relay.
    Then I used deoxit on the plugs socket and male pins, then clipped the plug back together.
    Started the car and the air pump runs for 2-3mins, then valve closes and it shuts off. After a minute or two it reactivates as the relay starts clacking away.
    Advice at this point?


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  4. F129b

    F129b Formula Junior

    Feb 6, 2004
    478
    oc, calif.
    Full Name:
    Robert
    So, to recap..
    -relay does not click away during initial warm up(when pump is and should be on) & air pump does shut off for some period of time after warm up
    -all 3 relays I’ve tried exhibit same clacking away as air pump energizes spontaneously during a drive-long after car is warmed up and pump should be off
    -if I ground the #14 plug socket to the door pin latch, the air pump runs and relay is quiet


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  5. Qavion

    Qavion F1 Veteran
    Silver Subscribed

    Feb 20, 2015
    5,188
    Sydney
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    Ian Riddell
    So all normal so far....

    You originally said the pump seems to run all the time. Have you refined that to "runs longer than expected after warmup"?

    It does seem more and more like an ECU problem (unfortunately). i.e. the ECU is having problems controlling the relay coil.

    You may find a Ferrari tech willing to let you borrow an ECU. I could suggest putting an earth on ECU plug socket #57 as shown in post 25 (with the car warmed up) to eliminate all the wiring as a potential fault, but, to be honest, I think this would be wasting time.
     
  6. F129b

    F129b Formula Junior

    Feb 6, 2004
    478
    oc, calif.
    Full Name:
    Robert
    Thank you. When I said “all the time” indeed I meant that it runs frequently (w associated relay clacking) after warm up. There is an initial “shut off”, but it does reactivate.
    Strangely-though perhaps relevant, it seems as though the pitch (rpm) of the air pump motor increases with engine rpm.


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  8. F129b

    F129b Formula Junior

    Feb 6, 2004
    478
    oc, calif.
    Full Name:
    Robert
    In your opinion, does this issue portend other impending ECU probs?
    Can ECU be diagnosed & fixed? Seems a shame to replace the $2k ECU for this silly prob with a non-essential circuit.


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  9. Qavion

    Qavion F1 Veteran
    Silver Subscribed

    Feb 20, 2015
    5,188
    Sydney
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    Ian Riddell
    There are repairers who advertise their services. e.g.

    https://www.ecudoctors.com/products/ferrari-355-f355-ecu-bosch-0261204186-m5-2#

    ...which reminds me, whatever ECU you put in there (borrowed, repaired or new), you will need someone to sync it with the alarm system.

    Sorry, I have no experience with the repair of these devices and how likely it is that the fault will develop into something bigger.

    Strange. Could pump speed be based on voltage? If your alternator is producing higher voltages at higher rpms (and the regulators are allowing over voltage), and the pump is responding to those voltages? Excessive voltage can also affect the ECU, but ECUs have a reasonable voltage operating range. Higher throttle openings also produce more vacuum, but the secondary air system only uses the vacuum to operate the secondary air solenoid.

    Lots of wild speculation, here.

    Experts?
     
  10. m.stojanovic

    m.stojanovic Formula 3
    Silver Subscribed

    Dec 22, 2011
    2,149
    Malaysia - KL
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    Miroljub Stojanovic
    The pump motor (or any other electric motor) is sensitive to voltage fluctuations which will cause motor rpm to fluctuate. However, it should be very small (almost none) with a good alternator. Certainly worth checking the alternator voltages (on the battery terminals) at idle and at revs. Maybe, after all, the pump relay pulsing could be due to insufficient voltage from the alternator. ECU-s have very good overvoltage protection but can go "crazy" if the voltage is too low.
     
  11. GTO Joe

    GTO Joe Formula Junior
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    Feb 15, 2013
    797
    Charlotte, NC
    Full Name:
    Joseph Troutwine
    Miro brings up a good point about the voltage. How old is your battery? I know with my C7 Vette if the battery starts to get old all kinds of weird things can begin to happen even if the battery has enough juice to start the car. Easy to check the condition of it with a load test.
     
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  13. F129b

    F129b Formula Junior

    Feb 6, 2004
    478
    oc, calif.
    Full Name:
    Robert
    Well I’m pleased to report that the issue seems to be that a chafed wire from the loom as it passes through the bulkhead appears to have been the problem. (Credit to MarkPhD for the speculative diagnosis)
    It was not poss to visualize said wire, but wrapping the metal edge of the chassis cutout with some fabric tape eliminated the clacking relay & air pump activation...for now


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