Modding 5NF.S8 to 5NF.T1 (aka HW104 to HW104) for Stilo 1.6
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  1. #1
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    Lightbulb Modding 5NF.S8 to 5NF.T1 (aka HW104 to HW104) for Stilo 1.6

    Hello!

    Having earned a ton of knowledge in this forum, I think it's time to help expand this knowledge base even more.

    While searching for an undamaged 5NF.T1/T9 ECU for my FIAT Stilo 1.6, I noticed that apart from the problematic design, the ECU gets destroyed for being mounted on top of the engine.

    However, the same variant of ECU (5NF with some variant of Motorola 68000 CPU) was used on some FIAT Panda and Punto 1.2 8v engines. In those engines (thankfully) the ECU was NOT mounted on top of the engine, but on the side of the battery (at least for the Panda, as far as I know). So this means that at least the BGA connections will be in good shape and those ECUs should live longer, making them perfect candidates for our 1.6 Stilos.

    So I already know that the main difference between HW102 and HW104 ECUs is the fact that the Stilo one (HW102) has 4 ignition coil drivers (ST VB025MSP) and HW104 has only 2 ignition coil drivers (same ST VB025MSP). See photos attached. In the HW104 variant 2 slots for the coil drivers are physically left empty.

    Now my theory: in order to convert HW104 to HW102 to use a Panda/Punto 5NF.S5 or 5NF.S8 the only thing we need to do is to solder the 2 missing coil drivers to their board pads. And of course afterwards we flash the EEPROM and Flash of the ECU with the original firmware found on any 5NF.T1 or 5NF.T9 Stilo ECU (ie with a Galletto Master V54).

    Has anyone done this before? I assume the procedure should be the same for the 5NF.T2 ECUs found in the FIAT Doblo 1.6 with the same (physical) engine. But these had the same mounting position, so I can't see the benefit of modding those ECUs.

    Bonus:

    My theory for the failure rate of the Magneti Marelli 5NF ECUs is the following:

    1. Bad design #1. These ECUs just can't handle the thermal output of those FIAT 1.6 engines. This resulted in: a) the melting of the connector pins. b) the destruction of the Motorola CPU on the hidden side of the PCB. c) capacitor failure.

    2. Zero protection for the ignition coil driver circuitry. Meaning that in case of a coil pack going bad, the returning charge would spike back to the ignition coil chips, either damaging them or damaging other parts of the ECU. I have seen 5NF ECUs on the Stilo that overheat on their own, albeit being mounted away from the engine and any other heat source. This is why I've seen people suggesting to replace all 4 coil packs after putting a new 5NF ECU to their cars. I do assume that the BOSCH ECUs found in Stilo 1.2 and 1.4 engines had some kind of protection for coil spike backfiring to the ECU. I think the older Magneti Marelli 59F ECUs had this problem too.

    Feel free to add your own experiences and theories on this topic! I've got some spare time now as I'm waiting for a used (but 100% working) IAW5NF.T9 ECU for my 1.6 Stilo as well as a Galletto Master V54 clone off Aliexpress to virginize it and plug it into my Stilo.

    iaw_hw102.jpg iaw_hw104.jpg
    Last edited by Zyborg; 7th January, 2022 at 02:05 AM. Reason: adding ECU PCB images

  2. #2
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    Default

    My thought is that the mircocontroller in the picture below may also be related to the hw.

    SM-A505F cihazımdan Tapatalk kullanılarak gönderildi

  3. #3
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    OK I will check it out. If the part number of this controller is the same, I guess it won't need to be changed. If it's different it will have to be replaced to match HW102.

 

 

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