360 - Adding extra ground strap from ECU’s to engine block to eradicate electrical gremlins? | FerrariChat

360 Adding extra ground strap from ECU’s to engine block to eradicate electrical gremlins?

Discussion in '360/430' started by Jaymac, Jul 16, 2025.

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  1. Jaymac

    Jaymac Formula Junior
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    Dec 18, 2020
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    Jeremy McCurdy
    I came across an old post recently where @Rifledriver mentioned that official Ferrari directives from many years ago advised to add an external ground strap from the Motronic ECU’s to the engine block in the case of difficult-to-diagnose electrical gremlins. I hadn’t seen this discussed before or since.
    Can anyone expound on this?
    Has anyone on here done this? If so, can you advise on which points you used on the block, and which type of ground strap you used?
    I’m not trying to fix a specific gremlin, moreso safeguarding against future issues, knowing how sensitive and susceptible these cars are to electric and voltage issues.
    Thoughts?
     
  2. flash32

    flash32 F1 Veteran

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    Dominick
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  3. Jaymac

    Jaymac Formula Junior
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    Good to know! I’m assuming it’s in his build thread, but I’ll reach out as well. Thanks Dom!
     
  4. flash32

    flash32 F1 Veteran

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  5. collegeboy

    collegeboy Formula 3

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    Yep! Up above. It certainly cannot hurt. Even an official Ferrari dealership told me they now do this on all 360/CS cars that come in.
     
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  6. Jaymac

    Jaymac Formula Junior
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    Thanks Dominick.
    Mikey, I see what looks like a new strap you added from the ECU to the engine block. What did you use for a strap; just a generic bare braided strap? And where was the actual point on the block that you used?
    Thanks!
     
  7. L1MTD

    L1MTD Karting

    Jun 2, 2019
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    I was just thinking about this and voila, a thread about this.

    I’d love photos if anyone can provide them.
     
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  8. Jaymac

    Jaymac Formula Junior
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    Maybe @collegeboy will chime in, but while chatting with him on IG, he said he used 2 pieces of 16ga wire wrapped in a spiral, and grounded them out to a bolt on the fuel rail. He mentioned that this is what some Ferrari dealerships are doing now as standard whenever a 360/CS comes in.
    Hopefully he’ll chime in to see if I’m paraphrasing correctly.
     
  9. collegeboy

    collegeboy Formula 3

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    Can't remember if it was 16g, but something small, and two of them together with new heat shrink eyelets, then the wires themselves in sleeving so it looked professional.
     
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  10. FlyingHaggisRacing

    FlyingHaggisRacing Formula 3

    Jul 2, 2013
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    Grounded both heads and block.
    That was 10years ago - never had an electrical issue.
    Agree, it's anecdotal, but there is no downside.
     
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  11. Jaymac

    Jaymac Formula Junior
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    Do you remember which points you used on each end of those grounds?
     
  12. L1MTD

    L1MTD Karting

    Jun 2, 2019
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    Photos would be incredible in this thread if possible.
     
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  13. clean512

    clean512 Formula 3

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    I could see one of the 4 mounts on the ecu and 1 of the two mounts for the fuel rail. Both are 6mm bolt so a eyelet for that size and some quality 14g or 16g black wire would be fine
     
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  14. Jaymac

    Jaymac Formula Junior
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    also, Josh, I just now saw that you’re @jtcarprojects; I follow you as @jaymac360981, as well as my local FCA account. Small world!
     
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  15. RedNeck

    RedNeck F1 World Champ
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    I second this
     
  16. L1MTD

    L1MTD Karting

    Jun 2, 2019
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    I did this myself yesterday so thought I’d provide the thing I’ve been asking for.

    Couple of things:

    -I used 10g wire

    -connected at the frame, touching and grounding to the same place each bank ECU grounds to

    -then I went to the nearest fuel rail mount bolt. I had seen this mentioned above so I went that route, but…

    -I don’t know if I love this location. I used a ring connected but cut it open to make it a spade since I really didn’t want to risk taking the bolt all the way out and somehow messing with an injector seal etc.

    -So I prepped the connector and loosened just enough, and quickly, to slide the “spade” connector under and then quickly retighten. No idea if this made any difference but that was my logic

    -The worry would be the sealing issue but also torque applied to the bolt with this soft metal connector now under it. May look for another place in the future to ground on the engine side

    Now, the reason I wanted to do this is because I have been chasing 2 issues I have assumed is electrical/ground related:

    -on most first starts of the day I get a P0116 code for temp sensor plausibility. I have swapped a new sensor, new cap, full coolant flush from a trusted Indy and still have the issue.

    Also, it’s only on the first start of the day, after about 3 mins of running. I clear it, it never comes back the rest of the day

    -Then, almost every first start of the day I get a rough start as mentioned by the OP above. Almost like it runs on one bank for the first 10 secs or so then the other bank comes on.

    So between these 2 anomalies both happening at first start and never returning again, and the common mention of these cars having grounding issues as they moved to their first aluminum chassis, I decided to go to this grounding solution mentioned above.


    And……well, first start today, fired right up on all cylinders. No P0116 code. I haven’t driven it in roughly the last 50ish times without at least one of those issues and don’t think I’ve ever had it start the first time with having neither rear their head, since I bought it a year ago.

    Sample size of one day. I will update as I go but it would be a hell of a placebo to do that last night and wake up today having neither issue.

    uploading on my phone so can’t see if the photos are above or below the text here, but the photos just show where I mounted. Happy to elaborate more if needed.



    Image Unavailable, Please Login Image Unavailable, Please Login
     
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  17. RedNeck

    RedNeck F1 World Champ
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    Thanks for sharing!
     
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  18. Jaymac

    Jaymac Formula Junior
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    Good job! Glad to hear the first day came without reoccurrence of the previous issues, I look forward to hearing if it continues to do the trick!
    I believe I recall @Rifledriver mentioning that back in the day, they were instructed to connect the ground wire directly to the body of the ECU using one of its’ 4 mounting nuts, but I would have to double check that before I would be confident in that recollection. I might do both. One ground from an ECU nut to the grounding point, and one from the EC nut to the fuel rail.
     
  19. L1MTD

    L1MTD Karting

    Jun 2, 2019
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    Hmm I’d like to hear more on that as well. My logic was “this is where the ECU grounds itself”, but also isn’t the ECU mounted on rubber? It would be odd to need to ground the case when that’s the purpose of the ECU’s ground wire. But open to being wrong and redoing it.

    I have left the sides covering the ECU’s off for now and will leave them off until I hear more.
     
  20. Jaymac

    Jaymac Formula Junior
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    I recall finding it in an FChat post by Rifledriver years ago, so you may be able to search and find it in short order on here.
    I also think the logic would be to ground it between the nut that secures into the bolt and the body itself, so it would be all metal on metal. So even if the body of the ECU isn’t mounted to metals, the sole contact between the ECU, nut and grounding strap would all be metal.
    Again, I would want to find this post and make sure I’m barking up the right tree, as well.
     
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  21. Jaymac

    Jaymac Formula Junior
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    I’m sorry to say the additional ground straps didn’t affect my rough cold start. I’m happy to have them and keep them regardless, as I’ve read enough anecdotal evidence that grounding issues with these cars can cause errant errors. So I’ll just keep them in there anyway.
    @L1MTD, how has yours been?
     
  22. L1MTD

    L1MTD Karting

    Jun 2, 2019
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    Only on 2 total drives since I added them and both had no cold start issue or the CEL. Still very small sample but will update as I go.
     
  23. Jaymac

    Jaymac Formula Junior
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    That’s good though!
     
  24. L1MTD

    L1MTD Karting

    Jun 2, 2019
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    3rd drive resulted in the funky “one bank” start until the second bank started. But I sorta messed it up as I had to move two other cars in its way and forgot about the immobilizer, haha. No idea if that caused the issue.

    BUT, 3rd straight time with no code for the implausibility issue, which is def a change and not just a coincidence.
     
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  25. L1MTD

    L1MTD Karting

    Jun 2, 2019
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    Haha, well, upon cold start today, the car fired right up on all cylinders, but the implausible pre-code showed up.

    Haha so 3 starts with neither, then the next 2 with one but not the other. Odd.
     

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