308GTB QV Relays -what order? | FerrariChat
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308GTB QV Relays -what order?

Discussion in '308/328' started by NSXER, Jun 18, 2006.

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  1. NSXER

    NSXER Formula 3

    Jan 4, 2004
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    #1 NSXER, Jun 18, 2006
    I have an 84 308GTB QV and it is still not running correctly, I have narrowed it down to the relays for the jetronic unit (in the trunk). On that unit it has three relays, two on the side and one large silver one by itself (wehrle relay). I understand that this large relay has been discountinued. Does anyone know the replacement part and # for all three relays? Also, does anyone have a picture of the order with part numbers of the relays in the passenger compartment. I think that some of them are in the incorrect sockets and a good pic would help a ton. Thanks
     
  2. matteo

    matteo F1 World Champ

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    #2 matteo, Jun 18, 2006
    Are these specific to 84-85? I have an 83 and I don't have any relays in the trunk. I only have the 2 ECU's.

    My relay locations are in the fuse panel and foot well on the passenger side.
     
  3. NSXER

    NSXER Formula 3

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    #3 NSXER, Jun 18, 2006
    I found a schematic that shows which relays go in each location, but does anyone have the correct part number for the large silver relay on the jetronic? Thanks
     
  4. Sloan83qv

    Sloan83qv F1 Rookie
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    #4 Sloan83qv, Jun 18, 2006
    Yes, 84-85 have the lamda FI unit
     
  5. matteo

    matteo F1 World Champ

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    #5 matteo, Jun 18, 2006
    Ah... Learn something new everyday
     
  6. ferrarioldman

    ferrarioldman Formula 3
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    #6 ferrarioldman, Jun 18, 2006
    You have to get the relay for a 328 and switch the wires in the connector block to make it work correctly. This is the over voltage protection relay. There are many threads in the archives on this.
     
  7. CliffBeer

    CliffBeer Formula 3

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    #7 CliffBeer, Jun 19, 2006
    Last edited by a moderator: Sep 7, 2017
    If your car runs like dirt it may well be the relay for the Bosch ECU. Does your relay look like the pic below? If yes, and the integral fuse is blown then your car will certainly run poorly. Basically, your ECU has no power and therefore your engine is running blind. The silver relay below is the ECU relay and it is actually a porsch 928 part: same as Porsche 928 32v 85-89 OEM part, part number 92861512400 (about $100 less through Porsche suppliers).
    Image Unavailable, Please Login
     
  8. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #8 Steve Magnusson, Jun 19, 2006
    As Tom mentioned, this is mainly an over-voltage protection device to prevent the injection ECU from getting damaged -- i.e., it has a Zener diode inside that goes into conduction and blows the 10A fuse if the alternator voltage goes too high. If the engine will run as-is, you might measure the voltage across the battery (i.e., the alternator output) at 2~3K RPM just to rule the alternator in or out (if the fuse is blown on that relay).

    If you would confirm the terminal #'s shown on the relay (30, 31, etc. -- there's four), I'd be glad to confirm what you should measure voltage-wise on each terminal when the engine is running (my current best guess is as below). The relay internals are shown the same on the two schematics, 308QV or 328 (confirming Tom's suggestion), but the terminal numbering on the 308QV schematic seems a little strange to me (and is illegible on my copy).

    For US 308QV (K-Jet with Lambda):

    terminal 30 = +12V always

    terminal 31 = ground

    terminal ? = +12V when the fuel pump is actually running

    terminal 30-? = (If the protection relay is working) +12V that goes to run the injection system (i.e., if terminal ? is at +12V and terminal 31 is at ground, terminal 30 is connected by the switch contacts inside the protection relay to terminal 30-)


    For US 328 (K-Jet with Lambda):

    terminal 30 = +12V always

    terminal 31 = ground

    terminal 15 = +12V when the fuel pump is actually running

    terminal 87 = (If the protection relay is working) +12V that goes to run the injection system (i.e., if terminal 15 is at +12V and terminal 31 is at ground, terminal 30 is connected by the switch contacts inside the relay to terminal 87)
     
  9. NSXER

    NSXER Formula 3

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    #9 NSXER, Jun 19, 2006
    I worked on it last night and did the following:
    Above the Jetronic is a small black tube (Fuse?) It cannot be opened and I took a resistance reading and it read 0. Two white wires come from the large silver relay and plug into it with a single connector and one white wire connects to the other end. Assuming that is was a fuse I put a regular automotive 3 amp fuse inline. I also put another relay in place of the large silver unit after taking some readings from it. Fired the car up and the Frequency valve began buzzing like it is suppose to and the car ran awesome. The picture above shows the fuse on the relay and I am wondering if on the newer cars they seperated the fuse and relay? The car is now a blast to drive and actually has power and does not stumble in lower rpms!!! Before, when I put the different relay in and the frequency valve was buzzing, I drove it and it ran fine above 4K rpm but stumbled down low. Now that I have a different fuse inline on the white wires it runs great down low as well.
    I do need to get the "correct" parts though.
     
  10. ferrarioldman

    ferrarioldman Formula 3
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    #10 ferrarioldman, Jun 19, 2006
    This is a diode, not a fuse. Do you not have a wiring diagram? It would help you a lot.
     
  11. Ricambi America

    Ricambi America F1 World Champ
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    #11 Ricambi America, Jun 19, 2006
    Haven't read the whole thread, but Cliff's aforementioned doo-dad is here:

    http://www.ricambiamerica.com/product_info.php?products_id=229521
     
  12. LarryS

    LarryS Formula Junior

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    #12 LarryS, Jun 20, 2006
    I was told the early relays had an internal fusible link and the later ones had a fuse built into the top.
    Mine quit working. I took the cover off of the relay, found the burnt fusible link, added an external fuse (10a I think). Been working fine for over a year.
    I also had a problem with the frequency valve buzzing intermittently, I had to clean the contact points in the relay.
     
  13. NSXER

    NSXER Formula 3

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    #13 NSXER, Jun 20, 2006
    LarryS,

    Great advice!! I pulled it apart and sure enough the lead (wire fuse) was broken, resoldered it and it worked! I did not put a fuse inline but I will now. The car is now running great thanks to everyone that chimed in. How do I make a donation to the site?
     

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